On Wed, 14 Jun 2017 11:40:08 +0900 Masami Hiramatsu <mhira...@kernel.org> wrote:
> On Fri, 9 Jun 2017 00:53:08 +0530 > "Naveen N. Rao" <naveen.n....@linux.vnet.ibm.com> wrote: > > > Add a test to verify that the registers passed in pt_regs on kprobe > > (trap), optprobe (jump) and kprobe_on_ftrace (ftrace_caller) are > > accurate. The tests are exercized if KPROBES_SANITY_TEST is enabled. > > Great! > > > > > Implemented for powerpc64. Other architectures will have to implement > > the relevant arch_* helpers and define HAVE_KPROBES_REGS_SANITY_TEST. > > Hmm, why don't you define that in arch/powerpc/Kconfig ? > Also, could you split this into 3 patches for each case ? > > > > > Signed-off-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com> > > --- > > arch/powerpc/include/asm/kprobes.h | 4 + > > arch/powerpc/lib/Makefile | 3 +- > > arch/powerpc/lib/test_kprobe_regs.S | 62 ++++++++++++ > > arch/powerpc/lib/test_kprobes.c | 115 ++++++++++++++++++++++ > > include/linux/kprobes.h | 11 +++ > > kernel/test_kprobes.c | 183 > > ++++++++++++++++++++++++++++++++++++ > > 6 files changed, 377 insertions(+), 1 deletion(-) > > create mode 100644 arch/powerpc/lib/test_kprobe_regs.S > > create mode 100644 arch/powerpc/lib/test_kprobes.c > > > > diff --git a/arch/powerpc/include/asm/kprobes.h > > b/arch/powerpc/include/asm/kprobes.h > > index 566da372e02b..10c91d3132a1 100644 > > --- a/arch/powerpc/include/asm/kprobes.h > > +++ b/arch/powerpc/include/asm/kprobes.h > > @@ -124,6 +124,10 @@ static inline int skip_singlestep(struct kprobe *p, > > struct pt_regs *regs, > > return 0; > > } > > #endif > > +#if defined(CONFIG_KPROBES_SANITY_TEST) && defined(CONFIG_PPC64) > > +#define HAVE_KPROBES_REGS_SANITY_TEST > > +void arch_kprobe_regs_set_ptregs(struct pt_regs *regs); > > +#endif > > #else > > static inline int kprobe_handler(struct pt_regs *regs) { return 0; } > > static inline int kprobe_post_handler(struct pt_regs *regs) { return 0; } > > diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile > > index 3c3146ba62da..8a0bb8e20179 100644 > > --- a/arch/powerpc/lib/Makefile > > +++ b/arch/powerpc/lib/Makefile > > @@ -27,7 +27,8 @@ obj64-y += copypage_64.o copyuser_64.o mem_64.o > > hweight_64.o \ > > > > obj64-$(CONFIG_SMP) += locks.o > > obj64-$(CONFIG_ALTIVEC) += vmx-helper.o > > -obj64-$(CONFIG_KPROBES_SANITY_TEST) += test_emulate_step.o > > +obj64-$(CONFIG_KPROBES_SANITY_TEST) += test_emulate_step.o > > test_kprobe_regs.o \ > > + test_kprobes.o > > > > obj-y += checksum_$(BITS).o checksum_wrappers.o > > > > diff --git a/arch/powerpc/lib/test_kprobe_regs.S > > b/arch/powerpc/lib/test_kprobe_regs.S > > new file mode 100644 > > index 000000000000..4e95eca6dcd3 > > --- /dev/null > > +++ b/arch/powerpc/lib/test_kprobe_regs.S > > @@ -0,0 +1,62 @@ > > +/* > > + * test_kprobe_regs: architectural helpers for validating pt_regs > > + * received on a kprobe. > > + * > > + * Copyright 2017 Naveen N. Rao <naveen.n....@linux.vnet.ibm.com> > > + * IBM Corporation > > + * > > + * This program is free software; you can redistribute it and/or > > + * modify it under the terms of the GNU General Public License > > + * as published by the Free Software Foundation; version 2 > > + * of the License. > > + */ > > + > > +#include <asm/ppc_asm.h> > > +#include <asm/asm-offsets.h> > > +#include <asm/ptrace.h> > > + > > +_GLOBAL(arch_kprobe_regs_function) > > + mflr r0 > > + std r0, LRSAVE(r1) > > + stdu r1, -SWITCH_FRAME_SIZE(r1) > > + > > + /* Tell pre handler about our pt_regs location */ > > + addi r3, r1, STACK_FRAME_OVERHEAD > > + bl arch_kprobe_regs_set_ptregs > > + > > + /* Load back our true LR */ > > + ld r0, (SWITCH_FRAME_SIZE + LRSAVE)(r1) > > + mtlr r0 > > + > > + /* Save all SPRs that we care about */ > > + mfctr r0 > > + std r0, _CTR(r1) > > + mflr r0 > > + std r0, _LINK(r1) > > + mfspr r0, SPRN_XER > > + std r0, _XER(r1) > > + mfcr r0 > > + std r0, _CCR(r1) > > + > > + /* Now, save all GPRs */ > > + SAVE_2GPRS(0, r1) > > + SAVE_10GPRS(2, r1) > > + SAVE_10GPRS(12, r1) > > + SAVE_10GPRS(22, r1) > > + > > + /* We're now ready to be probed */ > > +.global arch_kprobe_regs_probepoint > > +arch_kprobe_regs_probepoint: > > + nop > > + > > +#ifdef CONFIG_KPROBES_ON_FTRACE > > + /* Let's also test KPROBES_ON_FTRACE */ > > + bl kprobe_regs_kp_on_ftrace_target > > + nop > > +#endif > > + > > + /* All done */ > > + addi r1, r1, SWITCH_FRAME_SIZE > > + ld r0, LRSAVE(r1) > > + mtlr r0 > > + blr > > diff --git a/arch/powerpc/lib/test_kprobes.c > > b/arch/powerpc/lib/test_kprobes.c > > new file mode 100644 > > index 000000000000..23f7a7ffcdd6 > > --- /dev/null > > +++ b/arch/powerpc/lib/test_kprobes.c > > @@ -0,0 +1,115 @@ > > +/* > > + * test_kprobes: architectural helpers for validating pt_regs > > + * received on a kprobe. > > + * > > + * Copyright 2017 Naveen N. Rao <naveen.n....@linux.vnet.ibm.com> > > + * IBM Corporation > > + * > > + * This program is free software; you can redistribute it and/or > > + * modify it under the terms of the GNU General Public License > > + * as published by the Free Software Foundation; version 2 > > + * of the License. > > + */ > > + > > +#define pr_fmt(fmt) "Kprobe smoke test (regs): " fmt > > + > > +#include <asm/ptrace.h> > > +#include <linux/kernel.h> > > +#include <linux/kprobes.h> > > + > > +static struct pt_regs *r; > > + > > +void arch_kprobe_regs_set_ptregs(struct pt_regs *regs) > > +{ > > + r = regs; > > +} > > + > > +static int validate_regs(struct kprobe *p, struct pt_regs *regs, > > + int kp_on_ftrace, int post_handler) > > +{ > > + int i, ret = 1; > > + > > + if (!r) { > > + pr_err("pt_regs not setup!\n"); > > + return 0; > > + } > > + > > + if (regs->gpr[1] + STACK_FRAME_OVERHEAD != (unsigned long)r) { > > + /* We'll continue since this may just indicate an incorrect r1 > > */ > > + pr_err("pt_regs pointer/r1 doesn't point where we expect!\n"); > > + ret = 0; > > + } > > + > > + for (i = 0; i < 32; i++) { > > + /* KPROBES_ON_FTRACE may have stomped r0 in the prologue */ > > + if (r->gpr[i] != regs->gpr[i] && (!kp_on_ftrace || i != 0)) { > > + pr_err("gpr[%d] expected: 0x%lx, received: 0x%lx\n", > > + i, r->gpr[i], regs->gpr[i]); > > + ret = 0; > > + } > > + } Hmm, is this check really needed? See below(*) > > + > > + if (r->ctr != regs->ctr) { > > + pr_err("ctr expected: 0x%lx, received: 0x%lx\n", > > + r->ctr, regs->ctr); > > + ret = 0; > > + } > > + > > + if (r->link != regs->link && !kp_on_ftrace) { > > + pr_err("link expected: 0x%lx, received: 0x%lx\n", > > + r->link, regs->link); > > + ret = 0; > > + } > > + > > + /* KPROBES_ON_FTRACE *must* have clobbered link */ > > + if (r->link == regs->link && kp_on_ftrace) { > > + pr_err("link register not clobbered for KPROBES_ON_FTRACE!\n"); > > + ret = 0; > > + } > > + > > + if (r->xer != regs->xer) { > > + pr_err("xer expected: 0x%lx, received: 0x%lx\n", > > + r->xer, regs->xer); > > + ret = 0; > > + } > > + > > + if (r->ccr != regs->ccr) { > > + pr_err("ccr expected: 0x%lx, received: 0x%lx\n", > > + r->ccr, regs->ccr); > > + ret = 0; > > + } > > + > > + if (!post_handler && regs->nip != (unsigned long)p->addr) { > > + pr_err("nip expected: 0x%lx, received: 0x%lx\n", > > + (unsigned long)p->addr, regs->nip); > > + ret = 0; > > + } > > + > > + if (post_handler && > > + regs->nip != (unsigned long)p->addr + sizeof(kprobe_opcode_t)) { > > + pr_err("post_handler: nip expected: 0x%lx, received: 0x%lx\n", > > + (unsigned long)p->addr + > > sizeof(kprobe_opcode_t), > > + regs->nip); > > + ret = 0; > > + } > > + > > + return ret; > > +} > > + > > +int arch_kprobe_regs_pre_handler(struct kprobe *p, struct pt_regs *regs) > > +{ > > + return validate_regs(p, regs, 0, 0); > > +} > > + > > +int arch_kprobe_regs_post_handler(struct kprobe *p, struct pt_regs *regs, > > + unsigned long flags) > > +{ > > + return validate_regs(p, regs, 0, 1); > > +} > > + > > +#ifdef CONFIG_KPROBES_ON_FTRACE > > +int arch_kp_on_ftrace_pre_handler(struct kprobe *p, struct pt_regs *regs) > > +{ > > + return validate_regs(p, regs, 1, 0); > > +} > > +#endif > > diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h > > index 541df0b5b815..adfbb5b27acd 100644 > > --- a/include/linux/kprobes.h > > +++ b/include/linux/kprobes.h > > @@ -253,6 +253,17 @@ static inline void kretprobe_assert(struct > > kretprobe_instance *ri, > > > > #ifdef CONFIG_KPROBES_SANITY_TEST > > extern int init_test_probes(void); > > +#ifdef HAVE_KPROBES_REGS_SANITY_TEST > > +extern void arch_kprobe_regs_function(void); > > +extern void arch_kprobe_regs_probepoint(void); > > +extern int arch_kprobe_regs_pre_handler(struct kprobe *p, struct pt_regs > > *regs); > > +extern int arch_kprobe_regs_post_handler(struct kprobe *p, struct pt_regs > > *regs, > > + unsigned long flags); > > +#ifdef CONFIG_KPROBES_ON_FTRACE > > +extern void kprobe_regs_kp_on_ftrace_target(void); > > +extern int arch_kp_on_ftrace_pre_handler(struct kprobe *p, struct pt_regs > > *regs); > > +#endif > > +#endif > > #else > > static inline int init_test_probes(void) > > { > > diff --git a/kernel/test_kprobes.c b/kernel/test_kprobes.c > > index 0dbab6d1acb4..92011726cc69 100644 > > --- a/kernel/test_kprobes.c > > +++ b/kernel/test_kprobes.c > > @@ -19,6 +19,7 @@ > > #include <linux/kernel.h> > > #include <linux/kprobes.h> > > #include <linux/random.h> > > +#include <linux/workqueue.h> > > > > #define div_factor 3 > > > > @@ -334,6 +335,166 @@ static int test_kretprobes(void) > > } > > #endif /* CONFIG_KRETPROBES */ > > > > +#ifdef HAVE_KPROBES_REGS_SANITY_TEST > > +static int kprobe_regs_pre_handler(struct kprobe *p, struct pt_regs *regs) > > +{ > > + /* architectural helper returns 0 if validation fails */ > > + preh_val = arch_kprobe_regs_pre_handler(p, regs); > > + return 0; > > +} > > + > > +static void kprobe_regs_post_handler(struct kprobe *p, struct pt_regs > > *regs, > > + unsigned long flags) > > +{ > > + posth_val = arch_kprobe_regs_post_handler(p, regs, flags); > > +} > > + > > +static struct kprobe kpr = { > > + .symbol_name = "arch_kprobe_regs_probepoint", > > + .pre_handler = kprobe_regs_pre_handler, > > + .post_handler = kprobe_regs_post_handler, > > +}; > > + > > +static int test_kprobe_regs(void) > > +{ > > + int ret; > > + kprobe_opcode_t *addr; > > + > > + preh_val = 0; > > + posth_val = 0; > > + > > + ret = register_kprobe(&kpr); > > + if (ret < 0) { > > + pr_err("register_kprobe returned %d\n", ret); > > + return ret; > > + } > > + > > + /* Let's see if this probe was optimized */ > > + addr = kprobe_lookup_name(kpr.symbol_name, 0); What happen if addr == NULL? Since this already done in register_kprobe, you'd better use kpr.addr. > > + if (addr && *addr != BREAKPOINT_INSTRUCTION) { > > + pr_err("kprobe with post_handler optimized\n"); Hmm, this message is not appropriate if the arch doesn't support optprobe. Moreover, using BREAKPOINT_INSTRUCTION or not depends on each arch. So, I suggest this as; if (kprobe_optimized(&kpr)) { pr_err("kprobe with post_handler optimized\n"); goto error; And if you would like to check the instruction, please use probe_kernel_read(), and introduce arch-depend helper as below; } else if (arch_kprobe_validate_insn(&kpr)) { pr_err("kprobe breakpoint is not armed\n"); goto error; } Where (typical case, like ppc), int arch_kprobe_validate_insn(struct kprobe *kp) { kprobe_opcode_t buf; int ret; ret = probe_kernel_read(&buf, kp->addr, sizeof(buf)); if (ret) return ret; if (buf != BREAKPOINT_INSTRUCTION) return -EINVAL; return 0; } > > + unregister_kprobe(&kpr); > > + return -1; > > + } > > + > > + arch_kprobe_regs_function(); > > + unregister_kprobe(&kpr); > > + > > + if (preh_val == 0) { > > + pr_err("kprobe pre_handler regs validation failed\n"); > > + handler_errors++; > > + } > > + > > + if (posth_val == 0) { > > + pr_err("kprobe post_handler not called\n"); > > + handler_errors++; > > + } > > + > > + return 0; > > +} > > + > > +#ifdef CONFIG_KPROBES_ON_FTRACE > > +void kprobe_regs_kp_on_ftrace_target(void) > > +{ > > + posth_val = preh_val + div_factor; > > +} > > + > > +static int kp_on_ftrace_pre_handler(struct kprobe *p, struct pt_regs *regs) > > +{ > > + /* architectural helper returns 0 if validation fails */ > > + preh_val = arch_kp_on_ftrace_pre_handler(p, regs); Here, I think you'd better to call arch_kprobe_regs_pre_handler(p, regs); so that user can sure the handler's behavior has no difference. (*) If you would like to check the kprobe_on_ftrace arch inplementation, it should be a separated function, like arch_validate_kprobe_on_ftrace(p, regs); > > + return 0; > > +} > > + > > +static struct kprobe kprf = { > > + .symbol_name = "kprobe_regs_kp_on_ftrace_target", > > + .pre_handler = kp_on_ftrace_pre_handler, Also, we'd better add post_handler here so that it is able to check compatibilty. > > +}; > > + > > +static int test_kp_on_ftrace_regs(void) > > +{ > > + int ret; > > + > > + preh_val = 0; > > + > > + ret = register_kprobe(&kprf); > > + if (ret < 0) { > > + pr_err("register_kprobe returned %d\n", ret); > > + return ret; > > + } > > + > > + arch_kprobe_regs_function(); > > + unregister_kprobe(&kprf); > > + > > + if (preh_val == 0) { > > + pr_err("kp_on_ftrace pre_handler regs validation failed\n"); > > + handler_errors++; > > + } > > + > > + return 0; > > +} > > +#endif > > + > > +#ifdef CONFIG_OPTPROBES > > +static void test_optprobe_regs(struct work_struct *work); > > +static DECLARE_DELAYED_WORK(test_optprobe_regs_work, test_optprobe_regs); > > +int kprobe_registered; > > + > > +static struct kprobe kpor = { > > + .symbol_name = "arch_kprobe_regs_probepoint", > > + .pre_handler = kprobe_regs_pre_handler, > > +}; > > + > > +static void test_optprobe_regs_setup(void) > > +{ > > + int ret; > > + > > + ret = register_kprobe(&kpor); > > + if (ret < 0) { > > + pr_err("register_kprobe returned %d\n", ret); > > + return; > > + } > > + > > + kprobe_registered = 1; > > +} > > + > > +static void test_optprobe_regs(struct work_struct *work) > > +{ > > + kprobe_opcode_t *addr; > > + > > + if (!kprobe_registered) { > > + errors++; > > + goto summary; > > + } > > + > > + /* Let's see if this probe was optimized */ > > + addr = kprobe_lookup_name(kpor.symbol_name, 0); > > + if (addr && *addr == BREAKPOINT_INSTRUCTION) { Here, same as above, we need arch_optprobe_validate_insn(kp). Thank you, -- Masami Hiramatsu <mhira...@kernel.org>