Add sframe table to struct module and support sframe PC lookups when an .sframe section can be found on incoming modules. SFRAME_F_FDE_SORTED is not set for module .sframe, so FDEs are sorted right after the sframe header is read.
Co-developed-by: Weinan Liu <[email protected]> Signed-off-by: Weinan Liu <[email protected]> Suggested-by: Jens Remus <[email protected]> Reviewed-by: Jens Remus <[email protected]> Signed-off-by: Dylan Hatch <[email protected]> --- Changes since v7: - (sashiko) Move .sframe module init and sframe section fields to arch generic code. - (sashiko) Make sframe_find() noinstr. - (sashiko) Add preempt_notrace and instrumentation to __sframe_module_find() code path. --- arch/arm64/include/asm/module.h | 1 + include/linux/module.h | 5 ++ include/linux/sframe.h | 9 +++ kernel/module/main.c | 21 ++++++ kernel/unwind/Makefile | 4 -- kernel/unwind/sframe.c | 118 ++++++++++++++++++++++++++++++-- 6 files changed, 149 insertions(+), 9 deletions(-) diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h index fb9b88eebeb15..51a8891c24e88 100644 --- a/arch/arm64/include/asm/module.h +++ b/arch/arm64/include/asm/module.h @@ -6,6 +6,7 @@ #define __ASM_MODULE_H #include <asm-generic/module.h> +#include <linux/sframe.h> struct mod_plt_sec { int plt_shndx; diff --git a/include/linux/module.h b/include/linux/module.h index 96cc98568eea5..6b3f3d3cb3e8d 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -26,6 +26,7 @@ #include <linux/rbtree_latch.h> #include <linux/error-injection.h> #include <linux/tracepoint-defs.h> +#include <linux/sframe.h> #include <linux/srcu.h> #include <linux/static_call_types.h> #include <linux/dynamic_debug.h> @@ -577,6 +578,10 @@ struct module { #ifdef CONFIG_DYNAMIC_DEBUG_CORE struct _ddebug_info dyndbg_info; #endif +#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME + struct sframe_section sframe_sec; + bool sframe_init; +#endif } ____cacheline_aligned __randomize_layout; #ifndef MODULE_ARCH_INIT #define MODULE_ARCH_INIT {} diff --git a/include/linux/sframe.h b/include/linux/sframe.h index c1fe8ac7df7b3..1aa3e07725f4d 100644 --- a/include/linux/sframe.h +++ b/include/linux/sframe.h @@ -2,9 +2,12 @@ #ifndef _LINUX_SFRAME_H #define _LINUX_SFRAME_H +#include <linux/elf.h> #include <linux/init.h> #include <linux/unwind_types.h> +#include <asm-generic/module.h> + #ifdef CONFIG_UNWIND_SFRAME_LOOKUP struct sframe_section { @@ -15,6 +18,7 @@ struct sframe_section { unsigned long fres_start; unsigned long fres_end; unsigned int num_fdes; + bool fdes_sorted; signed char ra_off; signed char fp_off; @@ -23,12 +27,17 @@ struct sframe_section { extern struct sframe_section kernel_sfsec __ro_after_init; void __init init_sframe_table(void); +void sframe_module_init(struct module *mod, void *addr, unsigned int size); + extern int sframe_find(unsigned long ip, struct unwind_frame *frame); #else /* !CONFIG_UNWIND_SFRAME_LOOKUP */ static inline void __init init_sframe_table(void) {} +static inline void sframe_module_init(struct module *mod, void *addr, unsigned int size) {} + static inline int sframe_find(unsigned long ip, struct unwind_frame *frame) { return -EINVAL; } + #endif /* CONFIG_UNWIND_SFRAME_LOOKUP */ #endif /* _LINUX_SFRAME_H */ diff --git a/kernel/module/main.c b/kernel/module/main.c index c1b34dc1e89ac..8a4542b7e4a70 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -7,6 +7,7 @@ #define INCLUDE_VERMAGIC +#include <linux/elf.h> #include <linux/export.h> #include <linux/extable.h> #include <linux/moduleloader.h> @@ -3008,6 +3009,23 @@ static void module_deallocate(struct module *mod, struct load_info *info) free_mod_mem(mod); } +#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME + +static void setup_sframe(struct module *mod, const struct load_info *info) +{ + unsigned int sframe_size; + void *sframe = section_objs(info, ".sframe", 1, &sframe_size); + + if (sframe) + sframe_module_init(mod, sframe, sframe_size); +} + +#else + +static void setup_sframe(struct module *mod, const struct load_info *info) {} + +#endif + int __weak module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, struct module *me) @@ -3027,6 +3045,9 @@ static int post_relocation(struct module *mod, const struct load_info *info) /* Setup kallsyms-specific fields. */ add_kallsyms(mod, info); + /* Initialize sframe metadata. */ + setup_sframe(mod, info); + /* Arch-specific module finalizing. */ return module_finalize(info->hdr, info->sechdrs, mod); } diff --git a/kernel/unwind/Makefile b/kernel/unwind/Makefile index c5d953e48fe82..13254e6a7bb6d 100644 --- a/kernel/unwind/Makefile +++ b/kernel/unwind/Makefile @@ -1,8 +1,4 @@ obj-$(CONFIG_UNWIND_USER) += user.o deferred.o KCOV_INSTRUMENT_sframe.o := n - KASAN_SANITIZE_sframe.o := n - KCSAN_SANITIZE_sframe.o := n - - CFLAGS_REMOVE_sframe.o = $(CC_FLAGS_FTRACE) obj-$(CONFIG_UNWIND_SFRAME_LOOKUP) += sframe.o diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index ec81110a36796..33883408581da 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -6,8 +6,10 @@ #define pr_fmt(fmt) "sframe: " fmt #include <linux/mm.h> +#include <linux/rcupdate.h> #include <linux/string_helpers.h> #include <linux/sframe.h> +#include <linux/sort.h> #include <linux/unaligned.h> #include <linux/unwind_types.h> #include <linux/kallsyms.h> @@ -95,6 +97,9 @@ static __always_inline int __find_fde(struct sframe_section *sec, struct sframe_fde_v3 *first, *low, *high, *found = NULL; int ret; + if (!sec->fdes_sorted) + return -EINVAL; + first = (void *)sec->fdes_start; low = first; high = first + sec->num_fdes - 1; @@ -406,12 +411,53 @@ static __always_inline int __sframe_find(struct sframe_section *sec, return __find_fre(sec, &fde, ip, frame); } -notrace int sframe_find(unsigned long ip, struct unwind_frame *frame) +#ifdef CONFIG_MODULES + +static __always_inline int __sframe_find_module(unsigned long ip, + struct unwind_frame *frame) +{ + struct module *mod; + int ret; + + if (!rcu_is_watching()) + return -EINVAL; + + instrumentation_begin(); + scoped_guard(preempt_notrace) { + mod = __module_text_address(ip); + if (mod && smp_load_acquire(&mod->sframe_init)) + ret = __sframe_find(&mod->sframe_sec, ip, frame); + else + ret = -EINVAL; + } + instrumentation_end(); + + return ret; +} + +#else + +static __always_inline int __sframe_find_module(unsigned long ip, + struct unwind_frame *frame) +{ + return -EINVAL; +} + +#endif + +noinstr int sframe_find(unsigned long ip, struct unwind_frame *frame) { - if (!frame || !sframe_init) + if (!frame) return -EINVAL; - return __sframe_find(&kernel_sfsec, ip, frame); + if (__is_kernel_text(ip) || is_kernel_inittext(ip)) { + if (!sframe_init) + return -EINVAL; + + return __sframe_find(&kernel_sfsec, ip, frame); + } + + return __sframe_find_module(ip, frame); } NOKPROBE_SYMBOL(sframe_find); @@ -431,7 +477,6 @@ static int sframe_read_header(struct sframe_section *sec) if (shdr->preamble.magic != SFRAME_MAGIC || shdr->preamble.version != SFRAME_VERSION_3 || - !(shdr->preamble.flags & SFRAME_F_FDE_SORTED) || !(shdr->preamble.flags & SFRAME_F_FDE_FUNC_START_PCREL) || shdr->auxhdr_len) { pr_debug("bad/unsupported sframe header\n"); @@ -455,6 +500,7 @@ static int sframe_read_header(struct sframe_section *sec) return -EINVAL; } + sec->fdes_sorted = shdr->preamble.flags & SFRAME_F_FDE_SORTED; sec->num_fdes = num_fdes; sec->fdes_start = fdes_start; sec->fres_start = fres_start; @@ -471,10 +517,72 @@ void __init init_sframe_table(void) kernel_sfsec.sframe_start = (unsigned long)__start_sframe; kernel_sfsec.sframe_end = (unsigned long)__end_sframe; - if (sframe_read_header(&kernel_sfsec)) { + if (sframe_read_header(&kernel_sfsec) || !kernel_sfsec.fdes_sorted) { pr_warn("invalid vmlinux SFrame header\n"); return; } sframe_init = true; } + +#ifdef CONFIG_MODULES + +static int sframe_sort_cmp_fde(const void *a, const void *b) +{ + const struct sframe_fde_v3 *fde_a = a, *fde_b = b; + unsigned long func_start_a, func_start_b; + + func_start_a = (unsigned long)fde_a + fde_a->func_start_off; + func_start_b = (unsigned long)fde_b + fde_b->func_start_off; + + return cmp_int(func_start_a, func_start_b); +} + +static void sframe_sort_swap_fde(void *a, void *b, int size) +{ + struct sframe_fde_v3 *fde_a = a, *fde_b = b; + struct sframe_fde_v3 temp; + long delta; + + /* Swap potentially unaligned FDE */ + memcpy(&temp, fde_a, sizeof(struct sframe_fde_v3)); + memcpy(fde_a, fde_b, sizeof(struct sframe_fde_v3)); + memcpy(fde_b, &temp, sizeof(struct sframe_fde_v3)); + + /* Adjust FDE function start offset from FDE */ + delta = (long)((unsigned long)fde_b - (unsigned long)fde_a); + fde_a->func_start_off += delta; + fde_b->func_start_off -= delta; +} + +static void sframe_sort_fdes(struct sframe_section *sec) +{ + void *fdes = (void *)sec->fdes_start; + size_t num_fdes = sec->num_fdes; + + if (sec->fdes_sorted) + return; + + sort(fdes, num_fdes, sizeof(struct sframe_fde_v3), + sframe_sort_cmp_fde, sframe_sort_swap_fde); + sec->fdes_sorted = true; +} + +void sframe_module_init(struct module *mod, void *addr, unsigned int size) +{ + struct sframe_section *sec = &mod->sframe_sec; + + sec->sframe_start = (unsigned long)addr; + sec->sframe_end = (unsigned long)addr + size; + + if (sframe_read_header(sec)) { + pr_warn("invalid SFrame header in module %s\n", mod->name); + return; + } + sframe_sort_fdes(sec); + + /* Ensure SFrame is initialized when sframe_find() happens */ + smp_store_release(&mod->sframe_init, true); +} + +#endif -- 2.56.0.360.g66cac248cb-goog
