Refactor ftrace code and move to using ftrace_replace_code() to help simplify and make the code more maintainable.
- The existing ftrace.c code is moved to a separate file so that ppc64 elfv1 and clang -pg only support continue. This makes it possible to converge ppc32 and ppc64 support further. - Drop code to re-purpose compiler-generated long branches for ftrace use in support of large kernels. We still retain the ftrace stubs at the end of .text, so we now support kernels upto ~64MB. - Add ftrace_init_nop() to keep boot-time validations and init separate from runtime. - Implement ftrace_replace_code() to simplify overall ftrace setup. This will be especially useful when adding ability to nop out 'mflr r0' later, and for other subsequent ftrace features. - Add support for -fpatchable-function-entry. On ppc64, this needs gcc v13.1 so that the nops are generated at LEP. This also moves ppc32 to using the same two-instruction sequence as that of ppc64. This applies atop patches 1-3 of Nick's series for elfv2 conversion, as well as Nick's patch enabling -mprofile-kernel for elfv2 BE: - https://lore.kernel.org/all/20230505071850.228734-1-npig...@gmail.com/ - https://lore.kernel.org/all/20230506011814.8766-1-npig...@gmail.com/ This builds for me and passes a quick test, posting this as an early RFC. Signed-off-by: Naveen N Rao <nav...@kernel.org> --- arch/powerpc/Kconfig | 10 + arch/powerpc/Makefile | 5 + arch/powerpc/include/asm/ftrace.h | 10 +- arch/powerpc/include/asm/module.h | 4 - arch/powerpc/kernel/trace/Makefile | 8 +- arch/powerpc/kernel/trace/ftrace.c | 816 +++++------------ arch/powerpc/kernel/trace/ftrace_pg.c | 846 ++++++++++++++++++ .../gcc-check-fpatchable-function-entry.sh | 20 + 8 files changed, 1106 insertions(+), 613 deletions(-) create mode 100644 arch/powerpc/kernel/trace/ftrace_pg.c create mode 100755 arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 902b6b99f7ecd5..6db94723af7d30 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -187,6 +187,7 @@ config PPC select DYNAMIC_FTRACE if FUNCTION_TRACER select EDAC_ATOMIC_SCRUB select EDAC_SUPPORT + select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY if ARCH_USING_PATCHABLE_FUNCTION_ENTRY select GENERIC_ATOMIC64 if PPC32 select GENERIC_CLOCKEVENTS_BROADCAST if SMP select GENERIC_CMOS_UPDATE @@ -552,6 +553,15 @@ config MPROFILE_KERNEL def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-mprofile-kernel.sh $(CC) -mlittle-endian) if CPU_LITTLE_ENDIAN def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-mprofile-kernel.sh $(CC) -mbig-endian) if CPU_BIG_ENDIAN +config ARCH_HAS_PATCHABLE_FUNCTION_ENTRY_AT_LEP + depends on PPC64_ELF_ABI_V2 && FUNCTION_TRACER + def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh $(CC) -mlittle-endian) if CPU_LITTLE_ENDIAN + def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh $(CC) -mbig-endian) if CPU_BIG_ENDIAN + +config ARCH_USING_PATCHABLE_FUNCTION_ENTRY + depends on FUNCTION_TRACER && (PPC32 || PPC64_ELF_ABI_V2) + def_bool ARCH_HAS_PATCHABLE_FUNCTION_ENTRY_AT_LEP || (PPC32 && $(cc-option, -fpatchable-function-entry=2)) + config HOTPLUG_CPU bool "Support for enabling/disabling CPUs" depends on SMP && (PPC_PSERIES || \ diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index dca73f673d7046..de39478b1c9e9f 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -148,11 +148,16 @@ CFLAGS-$(CONFIG_PPC32) += $(call cc-option, $(MULTIPLEWORD)) CFLAGS-$(CONFIG_PPC32) += $(call cc-option,-mno-readonly-in-sdata) ifdef CONFIG_FUNCTION_TRACER +ifdef CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY +KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY +CC_FLAGS_FTRACE := -fpatchable-function-entry=2 +else CC_FLAGS_FTRACE := -pg ifdef CONFIG_MPROFILE_KERNEL CC_FLAGS_FTRACE += -mprofile-kernel endif endif +endif CFLAGS-$(CONFIG_TARGET_CPU_BOOL) += -mcpu=$(CONFIG_TARGET_CPU) AFLAGS-$(CONFIG_TARGET_CPU_BOOL) += -mcpu=$(CONFIG_TARGET_CPU) diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index 91c049d51d0e10..d1a16543a37b00 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -22,18 +22,26 @@ extern void _mcount(void); static inline unsigned long ftrace_call_adjust(unsigned long addr) { - /* relocation of mcount call site is the same as the address */ + if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) + addr += MCOUNT_INSN_SIZE; + return addr; } unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp); +struct module; +struct dyn_ftrace; struct dyn_arch_ftrace { struct module *mod; }; #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS +#define ftrace_need_init_nop() (true) +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec); +#define ftrace_init_nop ftrace_init_nop + struct ftrace_regs { struct pt_regs regs; }; diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h index ac53606c259430..a8e2e8339fb7f4 100644 --- a/arch/powerpc/include/asm/module.h +++ b/arch/powerpc/include/asm/module.h @@ -75,10 +75,6 @@ struct mod_arch_specific { #endif #ifdef CONFIG_DYNAMIC_FTRACE -# ifdef MODULE - asm(".section .ftrace.tramp,\"ax\",@nobits; .align 3; .previous"); -# endif /* MODULE */ - int module_trampoline_target(struct module *mod, unsigned long trampoline, unsigned long *target); int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs); diff --git a/arch/powerpc/kernel/trace/Makefile b/arch/powerpc/kernel/trace/Makefile index b16a9f9c0b35f2..2296bbbd775ac8 100644 --- a/arch/powerpc/kernel/trace/Makefile +++ b/arch/powerpc/kernel/trace/Makefile @@ -8,13 +8,13 @@ ifdef CONFIG_FUNCTION_TRACER CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE) endif -obj32-$(CONFIG_FUNCTION_TRACER) += ftrace_mprofile.o +obj32-$(CONFIG_FUNCTION_TRACER) += ftrace_mprofile.o ftrace.o ifdef CONFIG_MPROFILE_KERNEL -obj64-$(CONFIG_FUNCTION_TRACER) += ftrace_mprofile.o +obj64-$(CONFIG_FUNCTION_TRACER) += ftrace_mprofile.o ftrace.o else -obj64-$(CONFIG_FUNCTION_TRACER) += ftrace_64_pg.o +obj64-$(CONFIG_FUNCTION_TRACER) += ftrace_64_pg.o ftrace_pg.o endif -obj-$(CONFIG_FUNCTION_TRACER) += ftrace_low.o ftrace.o +obj-$(CONFIG_FUNCTION_TRACER) += ftrace_low.o obj-$(CONFIG_TRACING) += trace_clock.o obj-$(CONFIG_PPC64) += $(obj64-y) diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c index a47f303734233b..a9d57f338bd78e 100644 --- a/arch/powerpc/kernel/trace/ftrace.c +++ b/arch/powerpc/kernel/trace/ftrace.c @@ -28,64 +28,52 @@ #include <asm/syscall.h> #include <asm/inst.h> -/* - * We generally only have a single long_branch tramp and at most 2 or 3 plt - * tramps generated. But, we don't use the plt tramps currently. We also allot - * 2 tramps after .text and .init.text. So, we only end up with around 3 usable - * tramps in total. Set aside 8 just to be sure. - */ -#define NUM_FTRACE_TRAMPS 8 +#define NUM_FTRACE_TRAMPS 2 static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS]; -static ppc_inst_t -ftrace_call_replace(unsigned long ip, unsigned long addr, int link) +static ppc_inst_t ftrace_create_branch_inst(unsigned long ip, unsigned long addr, int link) { ppc_inst_t op; - addr = ppc_function_entry((void *)addr); - - /* if (link) set op to 'bl' else 'b' */ + WARN_ON(!is_offset_in_branch_range(addr - ip)); create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0); return op; } -static inline int -ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new) +static inline int ftrace_read_inst(unsigned long ip, ppc_inst_t *op) { - ppc_inst_t replaced; - - /* - * Note: - * We are paranoid about modifying text, as if a bug was to happen, it - * could cause us to read or write to someplace that could cause harm. - * Carefully read and modify the code with probe_kernel_*(), and make - * sure what we read is what we expected it to be before modifying it. - */ - - /* read the text we want to modify */ - if (copy_inst_from_kernel_nofault(&replaced, (void *)ip)) + if (copy_inst_from_kernel_nofault(op, (void *)ip)) { + pr_err("0x%lx: fetching instruction failed\n", ip); return -EFAULT; - - /* Make sure it is what we expect it to be */ - if (!ppc_inst_equal(replaced, old)) { - pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip, - ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old)); - return -EINVAL; } - /* replace the text with the new text */ - return patch_instruction((u32 *)ip, new); + return 0; } -/* - * Helper functions that are the same for both PPC64 and PPC32. - */ -static int test_24bit_addr(unsigned long ip, unsigned long addr) +static inline int ftrace_validate_inst(unsigned long ip, ppc_inst_t inst) { - addr = ppc_function_entry((void *)addr); + ppc_inst_t op; + int ret; - return is_offset_in_branch_range(addr - ip); + ret = ftrace_read_inst(ip, &op); + if (!ret && !ppc_inst_equal(op, inst)) { + pr_err("0x%lx: expected (%08lx) != found (%08lx)\n", + ip, ppc_inst_as_ulong(inst), ppc_inst_as_ulong(op)); + ret = -EINVAL; + } + + return ret; +} + +static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new) +{ + int ret = ftrace_validate_inst(ip, old); + + if (!ret) + ret = patch_instruction((u32 *)ip, new); + + return ret; } static int is_bl_op(ppc_inst_t op) @@ -93,138 +81,11 @@ static int is_bl_op(ppc_inst_t op) return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0); } -static int is_b_op(ppc_inst_t op) -{ - return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BRANCH(0); -} - -static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op) -{ - int offset; - - offset = PPC_LI(ppc_inst_val(op)); - /* make it signed */ - if (offset & 0x02000000) - offset |= 0xfe000000; - - return ip + (long)offset; -} - -#ifdef CONFIG_MODULES -static int -__ftrace_make_nop(struct module *mod, - struct dyn_ftrace *rec, unsigned long addr) -{ - unsigned long entry, ptr, tramp; - unsigned long ip = rec->ip; - ppc_inst_t op, pop; - - /* read where this goes */ - if (copy_inst_from_kernel_nofault(&op, (void *)ip)) { - pr_err("Fetching opcode failed.\n"); - return -EFAULT; - } - - /* Make sure that this is still a 24bit jump */ - if (!is_bl_op(op)) { - pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op)); - return -EINVAL; - } - - /* lets find where the pointer goes */ - tramp = find_bl_target(ip, op); - - pr_devel("ip:%lx jumps to %lx", ip, tramp); - - if (module_trampoline_target(mod, tramp, &ptr)) { - pr_err("Failed to get trampoline target\n"); - return -EFAULT; - } - - pr_devel("trampoline target %lx", ptr); - - entry = ppc_global_function_entry((void *)addr); - /* This should match what was called */ - if (ptr != entry) { - pr_err("addr %lx does not match expected %lx\n", ptr, entry); - return -EINVAL; - } - - if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) { - if (copy_inst_from_kernel_nofault(&op, (void *)(ip - 4))) { - pr_err("Fetching instruction at %lx failed.\n", ip - 4); - return -EFAULT; - } - - /* We expect either a mflr r0, or a std r0, LRSAVE(r1) */ - if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_MFLR(_R0))) && - !ppc_inst_equal(op, ppc_inst(PPC_INST_STD_LR))) { - pr_err("Unexpected instruction %08lx around bl _mcount\n", - ppc_inst_as_ulong(op)); - return -EINVAL; - } - } else if (IS_ENABLED(CONFIG_PPC64)) { - /* - * Check what is in the next instruction. We can see ld r2,40(r1), but - * on first pass after boot we will see mflr r0. - */ - if (copy_inst_from_kernel_nofault(&op, (void *)(ip + 4))) { - pr_err("Fetching op failed.\n"); - return -EFAULT; - } - - if (!ppc_inst_equal(op, ppc_inst(PPC_INST_LD_TOC))) { - pr_err("Expected %08lx found %08lx\n", PPC_INST_LD_TOC, - ppc_inst_as_ulong(op)); - return -EINVAL; - } - } - - /* - * When using -mprofile-kernel or PPC32 there is no load to jump over. - * - * Otherwise our original call site looks like: - * - * bl <tramp> - * ld r2,XX(r1) - * - * Milton Miller pointed out that we can not simply nop the branch. - * If a task was preempted when calling a trace function, the nops - * will remove the way to restore the TOC in r2 and the r2 TOC will - * get corrupted. - * - * Use a b +8 to jump over the load. - * XXX: could make PCREL depend on MPROFILE_KERNEL - * XXX: check PCREL && MPROFILE_KERNEL calling sequence - */ - if (IS_ENABLED(CONFIG_MPROFILE_KERNEL) || IS_ENABLED(CONFIG_PPC32)) - pop = ppc_inst(PPC_RAW_NOP()); - else - pop = ppc_inst(PPC_RAW_BRANCH(8)); /* b +8 */ - - if (patch_instruction((u32 *)ip, pop)) { - pr_err("Patching NOP failed.\n"); - return -EPERM; - } - - return 0; -} -#else -static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) -{ - return 0; -} -#endif /* CONFIG_MODULES */ - static unsigned long find_ftrace_tramp(unsigned long ip) { int i; - /* - * We have the compiler generated long_branch tramps at the end - * and we prefer those - */ - for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--) + for (i = 0; i < NUM_FTRACE_TRAMPS; i++) if (!ftrace_tramps[i]) continue; else if (is_offset_in_branch_range(ftrace_tramps[i] - ip)) @@ -233,449 +94,200 @@ static unsigned long find_ftrace_tramp(unsigned long ip) return 0; } -static int add_ftrace_tramp(unsigned long tramp) +static int ftrace_get_call_inst(struct dyn_ftrace *rec, unsigned long addr, ppc_inst_t *call_inst) { - int i; - - for (i = 0; i < NUM_FTRACE_TRAMPS; i++) - if (!ftrace_tramps[i]) { - ftrace_tramps[i] = tramp; - return 0; - } - - return -1; -} - -/* - * If this is a compiler generated long_branch trampoline (essentially, a - * trampoline that has a branch to _mcount()), we re-write the branch to - * instead go to ftrace_[regs_]caller() and note down the location of this - * trampoline. - */ -static int setup_mcount_compiler_tramp(unsigned long tramp) -{ - int i; - ppc_inst_t op; - unsigned long ptr; - - /* Is this a known long jump tramp? */ - for (i = 0; i < NUM_FTRACE_TRAMPS; i++) - if (ftrace_tramps[i] == tramp) - return 0; - - /* New trampoline -- read where this goes */ - if (copy_inst_from_kernel_nofault(&op, (void *)tramp)) { - pr_debug("Fetching opcode failed.\n"); - return -1; - } - - /* Is this a 24 bit branch? */ - if (!is_b_op(op)) { - pr_debug("Trampoline is not a long branch tramp.\n"); - return -1; - } - - /* lets find where the pointer goes */ - ptr = find_bl_target(tramp, op); - - if (ptr != ppc_global_function_entry((void *)_mcount)) { - pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr); - return -1; - } - - /* Let's re-write the tramp to go to ftrace_[regs_]caller */ - if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) - ptr = ppc_global_function_entry((void *)ftrace_regs_caller); - else - ptr = ppc_global_function_entry((void *)ftrace_caller); - - if (patch_branch((u32 *)tramp, ptr, 0)) { - pr_debug("REL24 out of range!\n"); - return -1; - } - - if (add_ftrace_tramp(tramp)) { - pr_debug("No tramp locations left\n"); - return -1; - } - - return 0; -} - -static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr) -{ - unsigned long tramp, ip = rec->ip; - ppc_inst_t op; - - /* Read where this goes */ - if (copy_inst_from_kernel_nofault(&op, (void *)ip)) { - pr_err("Fetching opcode failed.\n"); - return -EFAULT; - } - - /* Make sure that this is still a 24bit jump */ - if (!is_bl_op(op)) { - pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op)); - return -EINVAL; - } - - /* Let's find where the pointer goes */ - tramp = find_bl_target(ip, op); - - pr_devel("ip:%lx jumps to %lx", ip, tramp); - - if (setup_mcount_compiler_tramp(tramp)) { - /* Are other trampolines reachable? */ - if (!find_ftrace_tramp(ip)) { - pr_err("No ftrace trampolines reachable from %ps\n", - (void *)ip); - return -EINVAL; - } - } - - if (patch_instruction((u32 *)ip, ppc_inst(PPC_RAW_NOP()))) { - pr_err("Patching NOP failed.\n"); - return -EPERM; - } - - return 0; -} - -int ftrace_make_nop(struct module *mod, - struct dyn_ftrace *rec, unsigned long addr) -{ - unsigned long ip = rec->ip; - ppc_inst_t old, new; - - /* - * If the calling address is more that 24 bits away, - * then we had to use a trampoline to make the call. - * Otherwise just update the call site. - */ - if (test_24bit_addr(ip, addr)) { - /* within range */ - old = ftrace_call_replace(ip, addr, 1); - new = ppc_inst(PPC_RAW_NOP()); - return ftrace_modify_code(ip, old, new); - } else if (core_kernel_text(ip)) { - return __ftrace_make_nop_kernel(rec, addr); - } else if (!IS_ENABLED(CONFIG_MODULES)) { - return -EINVAL; - } - - /* - * Out of range jumps are called from modules. - * We should either already have a pointer to the module - * or it has been passed in. - */ - if (!rec->arch.mod) { - if (!mod) { - pr_err("No module loaded addr=%lx\n", addr); - return -EFAULT; - } - rec->arch.mod = mod; - } else if (mod) { - if (mod != rec->arch.mod) { - pr_err("Record mod %p not equal to passed in mod %p\n", - rec->arch.mod, mod); - return -EINVAL; - } - /* nothing to do if mod == rec->arch.mod */ - } else - mod = rec->arch.mod; - - return __ftrace_make_nop(mod, rec, addr); -} - -#ifdef CONFIG_MODULES -/* - * Examine the existing instructions for __ftrace_make_call. - * They should effectively be a NOP, and follow formal constraints, - * depending on the ABI. Return false if they don't. - */ -static bool expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1) -{ - if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) - return ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP())); - else - return ppc_inst_equal(op0, ppc_inst(PPC_RAW_BRANCH(8))) && - ppc_inst_equal(op1, ppc_inst(PPC_INST_LD_TOC)); -} - -static int -__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) -{ - ppc_inst_t op[2]; - void *ip = (void *)rec->ip; - unsigned long entry, ptr, tramp; struct module *mod = rec->arch.mod; - - /* read where this goes */ - if (copy_inst_from_kernel_nofault(op, ip)) - return -EFAULT; - - if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && - copy_inst_from_kernel_nofault(op + 1, ip + 4)) - return -EFAULT; - - if (!expected_nop_sequence(ip, op[0], op[1])) { - pr_err("Unexpected call sequence at %p: %08lx %08lx\n", ip, - ppc_inst_as_ulong(op[0]), ppc_inst_as_ulong(op[1])); - return -EINVAL; - } - - /* If we never set up ftrace trampoline(s), then bail */ - if (!mod->arch.tramp || - (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !mod->arch.tramp_regs)) { - pr_err("No ftrace trampoline\n"); - return -EINVAL; - } - - if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && rec->flags & FTRACE_FL_REGS) - tramp = mod->arch.tramp_regs; - else - tramp = mod->arch.tramp; - - if (module_trampoline_target(mod, tramp, &ptr)) { - pr_err("Failed to get trampoline target\n"); - return -EFAULT; - } - - pr_devel("trampoline target %lx", ptr); - - entry = ppc_global_function_entry((void *)addr); - /* This should match what was called */ - if (ptr != entry) { - pr_err("addr %lx does not match expected %lx\n", ptr, entry); - return -EINVAL; - } - - if (patch_branch(ip, tramp, BRANCH_SET_LINK)) { - pr_err("REL24 out of range!\n"); - return -EINVAL; - } - - return 0; -} -#else -static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) -{ - return 0; -} -#endif /* CONFIG_MODULES */ - -static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr) -{ - ppc_inst_t op; - void *ip = (void *)rec->ip; - unsigned long tramp, entry, ptr; - - /* Make sure we're being asked to patch branch to a known ftrace addr */ - entry = ppc_global_function_entry((void *)ftrace_caller); - ptr = ppc_global_function_entry((void *)addr); - - if (ptr != entry && IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) - entry = ppc_global_function_entry((void *)ftrace_regs_caller); - - if (ptr != entry) { - pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr); - return -EINVAL; - } - - /* Make sure we have a nop */ - if (copy_inst_from_kernel_nofault(&op, ip)) { - pr_err("Unable to read ftrace location %p\n", ip); - return -EFAULT; - } - - if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) { - pr_err("Unexpected call sequence at %p: %08lx\n", - ip, ppc_inst_as_ulong(op)); - return -EINVAL; - } - - tramp = find_ftrace_tramp((unsigned long)ip); - if (!tramp) { - pr_err("No ftrace trampolines reachable from %ps\n", ip); - return -EINVAL; - } - - if (patch_branch(ip, tramp, BRANCH_SET_LINK)) { - pr_err("Error patching branch to ftrace tramp!\n"); - return -EINVAL; - } - - return 0; -} - -int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) -{ unsigned long ip = rec->ip; - ppc_inst_t old, new; + unsigned long stub; - /* - * If the calling address is more that 24 bits away, - * then we had to use a trampoline to make the call. - * Otherwise just update the call site. - */ - if (test_24bit_addr(ip, addr)) { - /* within range */ - old = ppc_inst(PPC_RAW_NOP()); - new = ftrace_call_replace(ip, addr, 1); - return ftrace_modify_code(ip, old, new); + if (is_offset_in_branch_range(addr - ip)) { + /* Within range */ + stub = addr; } else if (core_kernel_text(ip)) { - return __ftrace_make_call_kernel(rec, addr); - } else if (!IS_ENABLED(CONFIG_MODULES)) { - /* We should not get here without modules */ + /* We would be branching to one of our ftrace stubs */ + stub = find_ftrace_tramp(ip); + if (!stub) { + pr_err("0x%lx: No ftrace stubs reachable\n", ip); + return -EINVAL; + } + } else if (IS_ENABLED(CONFIG_MODULES)) { + /* Module code would be going to one of the module stubs */ + stub = (addr == (unsigned long)ftrace_caller ? mod->arch.tramp : mod->arch.tramp_regs); + } else { return -EINVAL; } - /* - * Out of range jumps are called from modules. - * Being that we are converting from nop, it had better - * already have a module defined. - */ - if (!rec->arch.mod) { - pr_err("No module loaded\n"); - return -EINVAL; - } - - return __ftrace_make_call(rec, addr); + *call_inst = ftrace_create_branch_inst(ip, stub, 1); + return 0; } #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS -#ifdef CONFIG_MODULES -static int -__ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, - unsigned long addr) +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr) { - ppc_inst_t op; - unsigned long ip = rec->ip; - unsigned long entry, ptr, tramp; - struct module *mod = rec->arch.mod; + /* This should never be called since we override ftrace_replace_code() */ + WARN_ON(1); + return -EINVAL; +} +#endif - /* If we never set up ftrace trampolines, then bail */ - if (!mod->arch.tramp || !mod->arch.tramp_regs) { - pr_err("No ftrace trampoline\n"); +int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +{ + ppc_inst_t old, new; + int ret; + + /* This can only ever be called during module load */ + if (WARN_ON(!IS_ENABLED(CONFIG_MODULES) || core_kernel_text(rec->ip))) + return -EINVAL; + + old = ppc_inst(PPC_RAW_NOP()); + ret = ftrace_get_call_inst(rec, addr, &new); + if (ret) + return ret; + + return ftrace_modify_code(rec->ip, old, new); +} + +int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) +{ + /* + * This should never be called since we override ftrace_replace_code(), + * as well as ftrace_init_nop() + */ + WARN_ON(1); + return -EINVAL; +} + +void ftrace_replace_code(int enable) +{ + ppc_inst_t old, new, nop_inst, call_inst, new_call_inst; + unsigned long ip, new_addr, addr; + struct ftrace_rec_iter *iter; + struct dyn_ftrace *rec; + int ret = 0, update; + + for_ftrace_rec_iter(iter) { + rec = ftrace_rec_iter_record(iter); + update = ftrace_test_record(rec, enable); + ip = rec->ip; + new_addr = 0; + + switch (update) { + case FTRACE_UPDATE_IGNORE: + default: + continue; + case FTRACE_UPDATE_MODIFY_CALL: + addr = ftrace_get_addr_curr(rec); + new_addr = ftrace_get_addr_new(rec); + break; + case FTRACE_UPDATE_MAKE_CALL: + addr = ftrace_get_addr_new(rec); + break; + case FTRACE_UPDATE_MAKE_NOP: + addr = ftrace_get_addr_curr(rec); + break; + } + nop_inst = ppc_inst(PPC_RAW_NOP()); + ret = ftrace_get_call_inst(rec, addr, &call_inst); + if (!ret && new_addr) + ret = ftrace_get_call_inst(rec, new_addr, &new_call_inst); + if (ret) + goto out; + + switch (update) { + case FTRACE_UPDATE_MODIFY_CALL: + old = call_inst; + new = new_call_inst; + break; + case FTRACE_UPDATE_MAKE_CALL: + old = nop_inst; + new = call_inst; + break; + case FTRACE_UPDATE_MAKE_NOP: + new = nop_inst; + old = call_inst; + break; + } + + /* old == new when going to .ftrace.text stub for modify */ + if (!ppc_inst_equal(old, new)) + ret = ftrace_modify_code(ip, old, new); + if (ret) + goto out; + ftrace_update_record(rec, enable); + } + +out: + if (ret) + ftrace_bug(ret, rec); + return; +} + +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) +{ + unsigned long addr, ip = rec->ip; + ppc_inst_t old, new; + int ret = 0; + + /* Verify instructions surrounding the ftrace location */ + if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) { + /* Expect nops */ + ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_NOP())); + if (!ret) + ret = ftrace_validate_inst(ip, ppc_inst(PPC_RAW_NOP())); + } else if (IS_ENABLED(CONFIG_PPC32)) { + /* Expected sequence: 'mflr r0', 'stw r0,4(r1)', 'bl _mcount' */ + ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0))); + if (!ret) + ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STW(_R0, _R1, 4))); + } else if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) { + /* Expected sequence: 'mflr r0', 'bl _mcount' */ + ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_MFLR(_R0))); + } else { return -EINVAL; } - /* read where this goes */ - if (copy_inst_from_kernel_nofault(&op, (void *)ip)) { - pr_err("Fetching opcode failed.\n"); - return -EFAULT; - } + if (ret) + return ret; - /* Make sure that this is still a 24bit jump */ - if (!is_bl_op(op)) { - pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op)); - return -EINVAL; - } - - /* lets find where the pointer goes */ - tramp = find_bl_target(ip, op); - entry = ppc_global_function_entry((void *)old_addr); - - pr_devel("ip:%lx jumps to %lx", ip, tramp); - - if (tramp != entry) { - /* old_addr is not within range, so we must have used a trampoline */ - if (module_trampoline_target(mod, tramp, &ptr)) { - pr_err("Failed to get trampoline target\n"); + if (!core_kernel_text(ip)) { + if (!mod) { + pr_err("0x%lx: No module provided for non-kernel address\n", ip); return -EFAULT; } - - pr_devel("trampoline target %lx", ptr); - - /* This should match what was called */ - if (ptr != entry) { - pr_err("addr %lx does not match expected %lx\n", ptr, entry); - return -EINVAL; - } + rec->arch.mod = mod; } - /* The new target may be within range */ - if (test_24bit_addr(ip, addr)) { - /* within range */ - if (patch_branch((u32 *)ip, addr, BRANCH_SET_LINK)) { - pr_err("REL24 out of range!\n"); - return -EINVAL; - } - - return 0; - } - - if (rec->flags & FTRACE_FL_REGS) - tramp = mod->arch.tramp_regs; - else - tramp = mod->arch.tramp; - - if (module_trampoline_target(mod, tramp, &ptr)) { - pr_err("Failed to get trampoline target\n"); - return -EFAULT; - } - - pr_devel("trampoline target %lx", ptr); - - entry = ppc_global_function_entry((void *)addr); - /* This should match what was called */ - if (ptr != entry) { - pr_err("addr %lx does not match expected %lx\n", ptr, entry); - return -EINVAL; - } - - if (patch_branch((u32 *)ip, tramp, BRANCH_SET_LINK)) { - pr_err("REL24 out of range!\n"); - return -EINVAL; - } - - return 0; -} -#else -static int __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr) -{ - return 0; -} -#endif - -int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, - unsigned long addr) -{ - unsigned long ip = rec->ip; - ppc_inst_t old, new; - - /* - * If the calling address is more that 24 bits away, - * then we had to use a trampoline to make the call. - * Otherwise just update the call site. - */ - if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) { - /* within range */ - old = ftrace_call_replace(ip, old_addr, 1); - new = ftrace_call_replace(ip, addr, 1); - return ftrace_modify_code(ip, old, new); - } else if (core_kernel_text(ip)) { + /* Nop-out the ftrace location */ + new = ppc_inst(PPC_RAW_NOP()); + addr = MCOUNT_ADDR; + if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) { + /* we instead patch-in the 'mflr r0' */ + old = ppc_inst(PPC_RAW_NOP()); + new = ppc_inst(PPC_RAW_MFLR(_R0)); + ret = ftrace_modify_code(ip - 4, old, new); + } else if (is_offset_in_branch_range(addr - ip)) { + /* Within range */ + old = ftrace_create_branch_inst(ip, addr, 1); + ret = ftrace_modify_code(ip, old, new); + } else if (core_kernel_text(ip) || (IS_ENABLED(CONFIG_MODULES) && mod)) { /* - * We always patch out of range locations to go to the regs - * variant, so there is nothing to do here + * We would be branching to a toolchain-generated stub, or to the module _mcount + * stub. Let's just confirm we have a 'bl' here. */ - return 0; - } else if (!IS_ENABLED(CONFIG_MODULES)) { - /* We should not get here without modules */ + ret = ftrace_read_inst(ip, &old); + if (ret) + return ret; + if (!is_bl_op(old)) { + pr_err("0x%lx: expected (bl) != found (%08lx)\n", ip, ppc_inst_as_ulong(old)); + return -EINVAL; + } + ret = patch_instruction((u32 *)ip, new); + } else { return -EINVAL; } - /* - * Out of range jumps are called from modules. - */ - if (!rec->arch.mod) { - pr_err("No module loaded\n"); - return -EINVAL; - } - - return __ftrace_modify_call(rec, old_addr, addr); + return ret; } -#endif int ftrace_update_ftrace_func(ftrace_func_t func) { @@ -684,14 +296,14 @@ int ftrace_update_ftrace_func(ftrace_func_t func) int ret; old = ppc_inst_read((u32 *)&ftrace_call); - new = ftrace_call_replace(ip, (unsigned long)func, 1); + new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1); ret = ftrace_modify_code(ip, old, new); /* Also update the regs callback function */ if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) { ip = (unsigned long)(&ftrace_regs_call); old = ppc_inst_read((u32 *)&ftrace_regs_call); - new = ftrace_call_replace(ip, (unsigned long)func, 1); + new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1); ret = ftrace_modify_code(ip, old, new); } @@ -723,6 +335,17 @@ void ftrace_free_init_tramp(void) } } +static void __init add_ftrace_tramp(unsigned long tramp) +{ + int i; + + for (i = 0; i < NUM_FTRACE_TRAMPS; i++) + if (!ftrace_tramps[i]) { + ftrace_tramps[i] = tramp; + return; + } +} + int __init ftrace_dyn_arch_init(void) { int i; @@ -745,14 +368,9 @@ int __init ftrace_dyn_arch_init(void) }; #endif - unsigned long addr; + unsigned long addr = FTRACE_REGS_ADDR; long reladdr; - if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) - addr = ppc_global_function_entry((void *)ftrace_regs_caller); - else - addr = ppc_global_function_entry((void *)ftrace_caller); - if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) { for (i = 0; i < 2; i++) { reladdr = addr - (unsigned long)tramp[i]; @@ -804,8 +422,8 @@ static int ftrace_modify_ftrace_graph_caller(bool enable) if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS)) return 0; - old = ftrace_call_replace(ip, enable ? stub : addr, 0); - new = ftrace_call_replace(ip, enable ? addr : stub, 0); + old = ftrace_create_branch_inst(ip, enable ? stub : addr, 0); + new = ftrace_create_branch_inst(ip, enable ? addr : stub, 0); return ftrace_modify_code(ip, old, new); } @@ -864,13 +482,3 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip, } #endif #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ - -#ifdef CONFIG_PPC64_ELF_ABI_V1 -char *arch_ftrace_match_adjust(char *str, const char *search) -{ - if (str[0] == '.' && search[0] != '.') - return str + 1; - else - return str; -} -#endif /* CONFIG_PPC64_ELF_ABI_V1 */ diff --git a/arch/powerpc/kernel/trace/ftrace_pg.c b/arch/powerpc/kernel/trace/ftrace_pg.c new file mode 100644 index 00000000000000..7b85c3b460a3c0 --- /dev/null +++ b/arch/powerpc/kernel/trace/ftrace_pg.c @@ -0,0 +1,846 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Code for replacing ftrace calls with jumps. + * + * Copyright (C) 2007-2008 Steven Rostedt <srost...@redhat.com> + * + * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box. + * + * Added function graph tracer code, taken from x86 that was written + * by Frederic Weisbecker, and ported to PPC by Steven Rostedt. + * + */ + +#define pr_fmt(fmt) "ftrace-powerpc: " fmt + +#include <linux/spinlock.h> +#include <linux/hardirq.h> +#include <linux/uaccess.h> +#include <linux/module.h> +#include <linux/ftrace.h> +#include <linux/percpu.h> +#include <linux/init.h> +#include <linux/list.h> + +#include <asm/cacheflush.h> +#include <asm/code-patching.h> +#include <asm/ftrace.h> +#include <asm/syscall.h> +#include <asm/inst.h> + +/* + * We generally only have a single long_branch tramp and at most 2 or 3 plt + * tramps generated. But, we don't use the plt tramps currently. We also allot + * 2 tramps after .text and .init.text. So, we only end up with around 3 usable + * tramps in total. Set aside 8 just to be sure. + */ +#define NUM_FTRACE_TRAMPS 8 +static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS]; + +static ppc_inst_t +ftrace_call_replace(unsigned long ip, unsigned long addr, int link) +{ + ppc_inst_t op; + + addr = ppc_function_entry((void *)addr); + + /* if (link) set op to 'bl' else 'b' */ + create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0); + + return op; +} + +static inline int +ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new) +{ + ppc_inst_t replaced; + + /* + * Note: + * We are paranoid about modifying text, as if a bug was to happen, it + * could cause us to read or write to someplace that could cause harm. + * Carefully read and modify the code with probe_kernel_*(), and make + * sure what we read is what we expected it to be before modifying it. + */ + + /* read the text we want to modify */ + if (copy_inst_from_kernel_nofault(&replaced, (void *)ip)) + return -EFAULT; + + /* Make sure it is what we expect it to be */ + if (!ppc_inst_equal(replaced, old)) { + pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip, + ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old)); + return -EINVAL; + } + + /* replace the text with the new text */ + return patch_instruction((u32 *)ip, new); +} + +/* + * Helper functions that are the same for both PPC64 and PPC32. + */ +static int test_24bit_addr(unsigned long ip, unsigned long addr) +{ + addr = ppc_function_entry((void *)addr); + + return is_offset_in_branch_range(addr - ip); +} + +static int is_bl_op(ppc_inst_t op) +{ + return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0); +} + +static int is_b_op(ppc_inst_t op) +{ + return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BRANCH(0); +} + +static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op) +{ + int offset; + + offset = PPC_LI(ppc_inst_val(op)); + /* make it signed */ + if (offset & 0x02000000) + offset |= 0xfe000000; + + return ip + (long)offset; +} + +#ifdef CONFIG_MODULES +static int +__ftrace_make_nop(struct module *mod, + struct dyn_ftrace *rec, unsigned long addr) +{ + unsigned long entry, ptr, tramp; + unsigned long ip = rec->ip; + ppc_inst_t op, pop; + + /* read where this goes */ + if (copy_inst_from_kernel_nofault(&op, (void *)ip)) { + pr_err("Fetching opcode failed.\n"); + return -EFAULT; + } + + /* Make sure that this is still a 24bit jump */ + if (!is_bl_op(op)) { + pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op)); + return -EINVAL; + } + + /* lets find where the pointer goes */ + tramp = find_bl_target(ip, op); + + pr_devel("ip:%lx jumps to %lx", ip, tramp); + + if (module_trampoline_target(mod, tramp, &ptr)) { + pr_err("Failed to get trampoline target\n"); + return -EFAULT; + } + + pr_devel("trampoline target %lx", ptr); + + entry = ppc_global_function_entry((void *)addr); + /* This should match what was called */ + if (ptr != entry) { + pr_err("addr %lx does not match expected %lx\n", ptr, entry); + return -EINVAL; + } + + if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) { + if (copy_inst_from_kernel_nofault(&op, (void *)(ip - 4))) { + pr_err("Fetching instruction at %lx failed.\n", ip - 4); + return -EFAULT; + } + + /* We expect either a mflr r0, or a std r0, LRSAVE(r1) */ + if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_MFLR(_R0))) && + !ppc_inst_equal(op, ppc_inst(PPC_INST_STD_LR))) { + pr_err("Unexpected instruction %08lx around bl _mcount\n", + ppc_inst_as_ulong(op)); + return -EINVAL; + } + } else if (IS_ENABLED(CONFIG_PPC64)) { + /* + * Check what is in the next instruction. We can see ld r2,40(r1), but + * on first pass after boot we will see mflr r0. + */ + if (copy_inst_from_kernel_nofault(&op, (void *)(ip + 4))) { + pr_err("Fetching op failed.\n"); + return -EFAULT; + } + + if (!ppc_inst_equal(op, ppc_inst(PPC_INST_LD_TOC))) { + pr_err("Expected %08lx found %08lx\n", PPC_INST_LD_TOC, + ppc_inst_as_ulong(op)); + return -EINVAL; + } + } + + /* + * When using -mprofile-kernel or PPC32 there is no load to jump over. + * + * Otherwise our original call site looks like: + * + * bl <tramp> + * ld r2,XX(r1) + * + * Milton Miller pointed out that we can not simply nop the branch. + * If a task was preempted when calling a trace function, the nops + * will remove the way to restore the TOC in r2 and the r2 TOC will + * get corrupted. + * + * Use a b +8 to jump over the load. + */ + if (IS_ENABLED(CONFIG_MPROFILE_KERNEL) || IS_ENABLED(CONFIG_PPC32)) + pop = ppc_inst(PPC_RAW_NOP()); + else + pop = ppc_inst(PPC_RAW_BRANCH(8)); /* b +8 */ + + if (patch_instruction((u32 *)ip, pop)) { + pr_err("Patching NOP failed.\n"); + return -EPERM; + } + + return 0; +} +#else +static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) +{ + return 0; +} +#endif /* CONFIG_MODULES */ + +static unsigned long find_ftrace_tramp(unsigned long ip) +{ + int i; + + /* + * We have the compiler generated long_branch tramps at the end + * and we prefer those + */ + for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--) + if (!ftrace_tramps[i]) + continue; + else if (is_offset_in_branch_range(ftrace_tramps[i] - ip)) + return ftrace_tramps[i]; + + return 0; +} + +static int add_ftrace_tramp(unsigned long tramp) +{ + int i; + + for (i = 0; i < NUM_FTRACE_TRAMPS; i++) + if (!ftrace_tramps[i]) { + ftrace_tramps[i] = tramp; + return 0; + } + + return -1; +} + +/* + * If this is a compiler generated long_branch trampoline (essentially, a + * trampoline that has a branch to _mcount()), we re-write the branch to + * instead go to ftrace_[regs_]caller() and note down the location of this + * trampoline. + */ +static int setup_mcount_compiler_tramp(unsigned long tramp) +{ + int i; + ppc_inst_t op; + unsigned long ptr; + + /* Is this a known long jump tramp? */ + for (i = 0; i < NUM_FTRACE_TRAMPS; i++) + if (ftrace_tramps[i] == tramp) + return 0; + + /* New trampoline -- read where this goes */ + if (copy_inst_from_kernel_nofault(&op, (void *)tramp)) { + pr_debug("Fetching opcode failed.\n"); + return -1; + } + + /* Is this a 24 bit branch? */ + if (!is_b_op(op)) { + pr_debug("Trampoline is not a long branch tramp.\n"); + return -1; + } + + /* lets find where the pointer goes */ + ptr = find_bl_target(tramp, op); + + if (ptr != ppc_global_function_entry((void *)_mcount)) { + pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr); + return -1; + } + + /* Let's re-write the tramp to go to ftrace_[regs_]caller */ + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) + ptr = ppc_global_function_entry((void *)ftrace_regs_caller); + else + ptr = ppc_global_function_entry((void *)ftrace_caller); + + if (patch_branch((u32 *)tramp, ptr, 0)) { + pr_debug("REL24 out of range!\n"); + return -1; + } + + if (add_ftrace_tramp(tramp)) { + pr_debug("No tramp locations left\n"); + return -1; + } + + return 0; +} + +static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr) +{ + unsigned long tramp, ip = rec->ip; + ppc_inst_t op; + + /* Read where this goes */ + if (copy_inst_from_kernel_nofault(&op, (void *)ip)) { + pr_err("Fetching opcode failed.\n"); + return -EFAULT; + } + + /* Make sure that this is still a 24bit jump */ + if (!is_bl_op(op)) { + pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op)); + return -EINVAL; + } + + /* Let's find where the pointer goes */ + tramp = find_bl_target(ip, op); + + pr_devel("ip:%lx jumps to %lx", ip, tramp); + + if (setup_mcount_compiler_tramp(tramp)) { + /* Are other trampolines reachable? */ + if (!find_ftrace_tramp(ip)) { + pr_err("No ftrace trampolines reachable from %ps\n", + (void *)ip); + return -EINVAL; + } + } + + if (patch_instruction((u32 *)ip, ppc_inst(PPC_RAW_NOP()))) { + pr_err("Patching NOP failed.\n"); + return -EPERM; + } + + return 0; +} + +int ftrace_make_nop(struct module *mod, + struct dyn_ftrace *rec, unsigned long addr) +{ + unsigned long ip = rec->ip; + ppc_inst_t old, new; + + /* + * If the calling address is more that 24 bits away, + * then we had to use a trampoline to make the call. + * Otherwise just update the call site. + */ + if (test_24bit_addr(ip, addr)) { + /* within range */ + old = ftrace_call_replace(ip, addr, 1); + new = ppc_inst(PPC_RAW_NOP()); + return ftrace_modify_code(ip, old, new); + } else if (core_kernel_text(ip)) { + return __ftrace_make_nop_kernel(rec, addr); + } else if (!IS_ENABLED(CONFIG_MODULES)) { + return -EINVAL; + } + + /* + * Out of range jumps are called from modules. + * We should either already have a pointer to the module + * or it has been passed in. + */ + if (!rec->arch.mod) { + if (!mod) { + pr_err("No module loaded addr=%lx\n", addr); + return -EFAULT; + } + rec->arch.mod = mod; + } else if (mod) { + if (mod != rec->arch.mod) { + pr_err("Record mod %p not equal to passed in mod %p\n", + rec->arch.mod, mod); + return -EINVAL; + } + /* nothing to do if mod == rec->arch.mod */ + } else + mod = rec->arch.mod; + + return __ftrace_make_nop(mod, rec, addr); +} + +#ifdef CONFIG_MODULES +/* + * Examine the existing instructions for __ftrace_make_call. + * They should effectively be a NOP, and follow formal constraints, + * depending on the ABI. Return false if they don't. + */ +static bool expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1) +{ + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) + return ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP())); + else + return ppc_inst_equal(op0, ppc_inst(PPC_RAW_BRANCH(8))) && + ppc_inst_equal(op1, ppc_inst(PPC_INST_LD_TOC)); +} + +static int +__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +{ + ppc_inst_t op[2]; + void *ip = (void *)rec->ip; + unsigned long entry, ptr, tramp; + struct module *mod = rec->arch.mod; + + /* read where this goes */ + if (copy_inst_from_kernel_nofault(op, ip)) + return -EFAULT; + + if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && + copy_inst_from_kernel_nofault(op + 1, ip + 4)) + return -EFAULT; + + if (!expected_nop_sequence(ip, op[0], op[1])) { + pr_err("Unexpected call sequence at %p: %08lx %08lx\n", ip, + ppc_inst_as_ulong(op[0]), ppc_inst_as_ulong(op[1])); + return -EINVAL; + } + + /* If we never set up ftrace trampoline(s), then bail */ + if (!mod->arch.tramp || + (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !mod->arch.tramp_regs)) { + pr_err("No ftrace trampoline\n"); + return -EINVAL; + } + + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && rec->flags & FTRACE_FL_REGS) + tramp = mod->arch.tramp_regs; + else + tramp = mod->arch.tramp; + + if (module_trampoline_target(mod, tramp, &ptr)) { + pr_err("Failed to get trampoline target\n"); + return -EFAULT; + } + + pr_devel("trampoline target %lx", ptr); + + entry = ppc_global_function_entry((void *)addr); + /* This should match what was called */ + if (ptr != entry) { + pr_err("addr %lx does not match expected %lx\n", ptr, entry); + return -EINVAL; + } + + if (patch_branch(ip, tramp, BRANCH_SET_LINK)) { + pr_err("REL24 out of range!\n"); + return -EINVAL; + } + + return 0; +} +#else +static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +{ + return 0; +} +#endif /* CONFIG_MODULES */ + +static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr) +{ + ppc_inst_t op; + void *ip = (void *)rec->ip; + unsigned long tramp, entry, ptr; + + /* Make sure we're being asked to patch branch to a known ftrace addr */ + entry = ppc_global_function_entry((void *)ftrace_caller); + ptr = ppc_global_function_entry((void *)addr); + + if (ptr != entry && IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) + entry = ppc_global_function_entry((void *)ftrace_regs_caller); + + if (ptr != entry) { + pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr); + return -EINVAL; + } + + /* Make sure we have a nop */ + if (copy_inst_from_kernel_nofault(&op, ip)) { + pr_err("Unable to read ftrace location %p\n", ip); + return -EFAULT; + } + + if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) { + pr_err("Unexpected call sequence at %p: %08lx\n", + ip, ppc_inst_as_ulong(op)); + return -EINVAL; + } + + tramp = find_ftrace_tramp((unsigned long)ip); + if (!tramp) { + pr_err("No ftrace trampolines reachable from %ps\n", ip); + return -EINVAL; + } + + if (patch_branch(ip, tramp, BRANCH_SET_LINK)) { + pr_err("Error patching branch to ftrace tramp!\n"); + return -EINVAL; + } + + return 0; +} + +int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +{ + unsigned long ip = rec->ip; + ppc_inst_t old, new; + + /* + * If the calling address is more that 24 bits away, + * then we had to use a trampoline to make the call. + * Otherwise just update the call site. + */ + if (test_24bit_addr(ip, addr)) { + /* within range */ + old = ppc_inst(PPC_RAW_NOP()); + new = ftrace_call_replace(ip, addr, 1); + return ftrace_modify_code(ip, old, new); + } else if (core_kernel_text(ip)) { + return __ftrace_make_call_kernel(rec, addr); + } else if (!IS_ENABLED(CONFIG_MODULES)) { + /* We should not get here without modules */ + return -EINVAL; + } + + /* + * Out of range jumps are called from modules. + * Being that we are converting from nop, it had better + * already have a module defined. + */ + if (!rec->arch.mod) { + pr_err("No module loaded\n"); + return -EINVAL; + } + + return __ftrace_make_call(rec, addr); +} + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +#ifdef CONFIG_MODULES +static int +__ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + ppc_inst_t op; + unsigned long ip = rec->ip; + unsigned long entry, ptr, tramp; + struct module *mod = rec->arch.mod; + + /* If we never set up ftrace trampolines, then bail */ + if (!mod->arch.tramp || !mod->arch.tramp_regs) { + pr_err("No ftrace trampoline\n"); + return -EINVAL; + } + + /* read where this goes */ + if (copy_inst_from_kernel_nofault(&op, (void *)ip)) { + pr_err("Fetching opcode failed.\n"); + return -EFAULT; + } + + /* Make sure that this is still a 24bit jump */ + if (!is_bl_op(op)) { + pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op)); + return -EINVAL; + } + + /* lets find where the pointer goes */ + tramp = find_bl_target(ip, op); + entry = ppc_global_function_entry((void *)old_addr); + + pr_devel("ip:%lx jumps to %lx", ip, tramp); + + if (tramp != entry) { + /* old_addr is not within range, so we must have used a trampoline */ + if (module_trampoline_target(mod, tramp, &ptr)) { + pr_err("Failed to get trampoline target\n"); + return -EFAULT; + } + + pr_devel("trampoline target %lx", ptr); + + /* This should match what was called */ + if (ptr != entry) { + pr_err("addr %lx does not match expected %lx\n", ptr, entry); + return -EINVAL; + } + } + + /* The new target may be within range */ + if (test_24bit_addr(ip, addr)) { + /* within range */ + if (patch_branch((u32 *)ip, addr, BRANCH_SET_LINK)) { + pr_err("REL24 out of range!\n"); + return -EINVAL; + } + + return 0; + } + + if (rec->flags & FTRACE_FL_REGS) + tramp = mod->arch.tramp_regs; + else + tramp = mod->arch.tramp; + + if (module_trampoline_target(mod, tramp, &ptr)) { + pr_err("Failed to get trampoline target\n"); + return -EFAULT; + } + + pr_devel("trampoline target %lx", ptr); + + entry = ppc_global_function_entry((void *)addr); + /* This should match what was called */ + if (ptr != entry) { + pr_err("addr %lx does not match expected %lx\n", ptr, entry); + return -EINVAL; + } + + if (patch_branch((u32 *)ip, tramp, BRANCH_SET_LINK)) { + pr_err("REL24 out of range!\n"); + return -EINVAL; + } + + return 0; +} +#else +static int __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr) +{ + return 0; +} +#endif + +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + unsigned long ip = rec->ip; + ppc_inst_t old, new; + + /* + * If the calling address is more that 24 bits away, + * then we had to use a trampoline to make the call. + * Otherwise just update the call site. + */ + if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) { + /* within range */ + old = ftrace_call_replace(ip, old_addr, 1); + new = ftrace_call_replace(ip, addr, 1); + return ftrace_modify_code(ip, old, new); + } else if (core_kernel_text(ip)) { + /* + * We always patch out of range locations to go to the regs + * variant, so there is nothing to do here + */ + return 0; + } else if (!IS_ENABLED(CONFIG_MODULES)) { + /* We should not get here without modules */ + return -EINVAL; + } + + /* + * Out of range jumps are called from modules. + */ + if (!rec->arch.mod) { + pr_err("No module loaded\n"); + return -EINVAL; + } + + return __ftrace_modify_call(rec, old_addr, addr); +} +#endif + +int ftrace_update_ftrace_func(ftrace_func_t func) +{ + unsigned long ip = (unsigned long)(&ftrace_call); + ppc_inst_t old, new; + int ret; + + old = ppc_inst_read((u32 *)&ftrace_call); + new = ftrace_call_replace(ip, (unsigned long)func, 1); + ret = ftrace_modify_code(ip, old, new); + + /* Also update the regs callback function */ + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) { + ip = (unsigned long)(&ftrace_regs_call); + old = ppc_inst_read((u32 *)&ftrace_regs_call); + new = ftrace_call_replace(ip, (unsigned long)func, 1); + ret = ftrace_modify_code(ip, old, new); + } + + return ret; +} + +/* + * Use the default ftrace_modify_all_code, but without + * stop_machine(). + */ +void arch_ftrace_update_code(int command) +{ + ftrace_modify_all_code(command); +} + +#ifdef CONFIG_PPC64 +#define PACATOC offsetof(struct paca_struct, kernel_toc) + +extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[]; + +void ftrace_free_init_tramp(void) +{ + int i; + + for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++) + if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) { + ftrace_tramps[i] = 0; + return; + } +} + +int __init ftrace_dyn_arch_init(void) +{ + int i; + unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init }; + u32 stub_insns[] = { + PPC_RAW_LD(_R12, _R13, PACATOC), + PPC_RAW_ADDIS(_R12, _R12, 0), + PPC_RAW_ADDI(_R12, _R12, 0), + PPC_RAW_MTCTR(_R12), + PPC_RAW_BCTR() + }; + unsigned long addr; + long reladdr; + + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) + addr = ppc_global_function_entry((void *)ftrace_regs_caller); + else + addr = ppc_global_function_entry((void *)ftrace_caller); + + reladdr = addr - kernel_toc_addr(); + + if (reladdr >= SZ_2G || reladdr < -(long)SZ_2G) { + pr_err("Address of %ps out of range of kernel_toc.\n", + (void *)addr); + return -1; + } + + for (i = 0; i < 2; i++) { + memcpy(tramp[i], stub_insns, sizeof(stub_insns)); + tramp[i][1] |= PPC_HA(reladdr); + tramp[i][2] |= PPC_LO(reladdr); + add_ftrace_tramp((unsigned long)tramp[i]); + } + + return 0; +} +#endif + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + +extern void ftrace_graph_call(void); +extern void ftrace_graph_stub(void); + +static int ftrace_modify_ftrace_graph_caller(bool enable) +{ + unsigned long ip = (unsigned long)(&ftrace_graph_call); + unsigned long addr = (unsigned long)(&ftrace_graph_caller); + unsigned long stub = (unsigned long)(&ftrace_graph_stub); + ppc_inst_t old, new; + + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS)) + return 0; + + old = ftrace_call_replace(ip, enable ? stub : addr, 0); + new = ftrace_call_replace(ip, enable ? addr : stub, 0); + + return ftrace_modify_code(ip, old, new); +} + +int ftrace_enable_ftrace_graph_caller(void) +{ + return ftrace_modify_ftrace_graph_caller(true); +} + +int ftrace_disable_ftrace_graph_caller(void) +{ + return ftrace_modify_ftrace_graph_caller(false); +} + +/* + * Hook the return address and push it in the stack of return addrs + * in current thread info. Return the address we want to divert to. + */ +static unsigned long +__prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp) +{ + unsigned long return_hooker; + int bit; + + if (unlikely(ftrace_graph_is_dead())) + goto out; + + if (unlikely(atomic_read(¤t->tracing_graph_pause))) + goto out; + + bit = ftrace_test_recursion_trylock(ip, parent); + if (bit < 0) + goto out; + + return_hooker = ppc_function_entry(return_to_handler); + + if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp)) + parent = return_hooker; + + ftrace_test_recursion_unlock(bit); +out: + return parent; +} + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS +void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *op, struct ftrace_regs *fregs) +{ + fregs->regs.link = __prepare_ftrace_return(parent_ip, ip, fregs->regs.gpr[1]); +} +#else +unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip, + unsigned long sp) +{ + return __prepare_ftrace_return(parent, ip, sp); +} +#endif +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ + +#ifdef CONFIG_PPC64_ELF_ABI_V1 +char *arch_ftrace_match_adjust(char *str, const char *search) +{ + if (str[0] == '.' && search[0] != '.') + return str + 1; + else + return str; +} +#endif /* CONFIG_PPC64_ELF_ABI_V1 */ diff --git a/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh b/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh new file mode 100755 index 00000000000000..410e349cc48428 --- /dev/null +++ b/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh @@ -0,0 +1,20 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 + +set -e +set -o pipefail + +# To debug, uncomment the following line +# set -x + +# Output from -fpatchable-function-entry can only vary on 64le, so this should +# not be invoked for other targets. Therefore we can pass in -m64 and -mabi +# explicitly, to take care of toolchains defaulting to other targets. + +# Test whether the nops are generated before the global entry point. +echo "int x; int func() { return x; }" | \ + $* -m64 -mabi=elfv2 -S -x c -O2 -fpatchable-function-entry=2,2 - -o - 2> /dev/null | \ + awk 'BEGIN { RS = ";" } /nop\n[[:space:]]*nop\n.*\nfunc:/ { print $0 }' | \ + grep -q "func:" || exit 0 + +exit 1 base-commit: 6d40746dbb75f85a18a0df005f1a8d6147abec22 prerequisite-patch-id: 3862cf6dc646260228e50b70c316cf15b1d7f384 prerequisite-patch-id: 859f60071f4e425c806fc7fe6c59e268232050a4 prerequisite-patch-id: ef23f712e50f106d689a550dae0f816285c1db3b prerequisite-patch-id: 8c6d31bb6ac4e4bef086fe502efa660ae99a96ca -- 2.40.1
