Add sframe table to mod_arch_specific 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 v6: - (sashiko) Check section flag SHF_ALLOC before reading in module .sframe. - (sashiko) Use READ_ONCE/WRITE_ONCE to enforce memory barrier when checking mod->arch.sframe_init. - Change IP range checks to strictly check text sections of vmlinux/module (instead of is_ksym_addr(ip) / __module_address(ip)). - (sashiko) Check kernel_sfsec.fdes_sorted during init, since SFRAME_F_FDE_SORTED is no longer required (in order to support modules). - (sashiko) Drop WARN_ON to pr_warn() when module sframe header read fails. - Drop sec->sec_type check in sframe_sort_fdes(), return void. --- arch/arm64/include/asm/module.h | 6 ++ arch/arm64/kernel/module.c | 5 ++ include/linux/sframe.h | 7 +++ kernel/unwind/sframe.c | 105 ++++++++++++++++++++++++++++++-- 4 files changed, 119 insertions(+), 4 deletions(-) diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h index fb9b88eebeb15..07f309c51eee6 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; @@ -17,6 +18,11 @@ struct mod_arch_specific { struct mod_plt_sec core; struct mod_plt_sec init; +#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME + struct sframe_section sframe_sec; + bool sframe_init; +#endif + /* for CONFIG_DYNAMIC_FTRACE */ struct plt_entry *ftrace_trampolines; struct plt_entry *init_ftrace_trampolines; diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c index 24adb581af0eb..69334e22be34e 100644 --- a/arch/arm64/kernel/module.c +++ b/arch/arm64/kernel/module.c @@ -18,6 +18,7 @@ #include <linux/moduleloader.h> #include <linux/random.h> #include <linux/scs.h> +#include <linux/sframe.h> #include <asm/alternative.h> #include <asm/insn.h> @@ -515,5 +516,9 @@ int module_finalize(const Elf_Ehdr *hdr, } } + s = find_section(hdr, sechdrs, ".sframe"); + if (s && (s->sh_flags & SHF_ALLOC)) + sframe_module_init(me, (void *)s->sh_addr, s->sh_size); + return module_init_ftrace_plt(hdr, sechdrs, me); } diff --git a/include/linux/sframe.h b/include/linux/sframe.h index c1fe8ac7df7b3..58a68de1396af 100644 --- a/include/linux/sframe.h +++ b/include/linux/sframe.h @@ -15,6 +15,7 @@ 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 +24,18 @@ 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 *sframe, size_t sframe_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 *sframe, + size_t sframe_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/unwind/sframe.c b/kernel/unwind/sframe.c index 9aac703f7ce6e..503d4a2beb50e 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -8,6 +8,7 @@ #include <linux/mm.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> @@ -94,6 +95,9 @@ 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; @@ -405,12 +409,43 @@ static __always_inline int __sframe_find(struct sframe_section *sec, return __find_fre(sec, &fde, ip, frame); } +#ifdef CONFIG_MODULES + +static __always_inline int __sframe_find_module(unsigned long ip, + struct unwind_frame *frame) +{ + struct module *mod; + + mod = __module_text_address(ip); + if (!mod || !READ_ONCE(mod->arch.sframe_init)) + return -EINVAL; + + return __sframe_find(&mod->arch.sframe_sec, ip, frame); +} + +#else + +static __always_inline int __sframe_find_module(unsigned long ip, + struct unwind_frame *frame) +{ + return -EINVAL; +} + +#endif + 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); } static int sframe_read_header(struct sframe_section *sec) @@ -429,7 +464,6 @@ 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"); @@ -453,6 +487,7 @@ 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; @@ -469,10 +504,72 @@ 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 *sframe, size_t sframe_size) +{ + struct sframe_section *sec = &mod->arch.sframe_sec; + + sec->sframe_start = (unsigned long)sframe; + sec->sframe_end = (unsigned long)sframe + sframe_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 */ + WRITE_ONCE(mod->arch.sframe_init, true); +} + +#endif -- 2.55.0.1082.g2b9226bbc0-goog
