From: Josh Poimboeuf <[email protected]> Add a debug feature to validate all .sframe sections when first loading the file rather than on demand.
[ Jens Remus: Add support for SFrame V3. Add support for PC-relative FDE function start offset. Adjust to rename of struct sframe_fre to sframe_fre_internal. Use %#x/%#lx format specifiers. ] [ Dylan Hatch: Adapt this patch for in-kernel sframe sections. ] Signed-off-by: Josh Poimboeuf <[email protected]> Reviewed-by: Indu Bhagat <[email protected]> Co-developed-by: Jens Remus <[email protected]> Signed-off-by: Jens Remus <[email protected]> Signed-off-by: Steven Rostedt <[email protected]> Co-developed-by: Dylan Hatch <[email protected]> Signed-off-by: Dylan Hatch <[email protected]> --- Adapted from commit 4b30214c7896 ("unwind_user/sframe: Add .sframe validation option") from Steven's sframe/core branch, and squashed in v6 patch "sframe: Introduce in-kernel SFRAME_VALIDATION". Changes include: - Squash in __read_fre_datawords() validation, given the patch reordering. - Drop safe_read_* user-access wrappers. - Call sframe_validate_section() when vmlinux/kernel sections load. --- arch/Kconfig | 18 +++++++++ kernel/unwind/sframe.c | 83 +++++++++++++++++++++++++++++++++++++++--- 2 files changed, 96 insertions(+), 5 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index cc59a5da80915..20aa63c93a0e2 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -538,6 +538,24 @@ config HAVE_UNWIND_KERNEL_SFRAME practice, this can provide more reliable stacktrace results than unwinding with frame pointers alone. +config SFRAME_VALIDATION + bool "Enable .sframe section debugging" + depends on UNWIND_SFRAME_LOOKUP + depends on DYNAMIC_DEBUG + help + When adding an .sframe section for an object, validate the entire + section immediately rather than on demand. + + This is a debug feature which is helpful for rooting out .sframe + section issues. If the .sframe section is corrupt, it will fail to + load immediately, with more information provided in dynamic printks. + + This has a significant page cache footprint due to its reading of the + entire .sframe section for every loaded module. Not recommended for + general use. + + If unsure, say N. + config HAVE_PERF_REGS bool help diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index c4715befb59b5..3386af16fc275 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -13,6 +13,7 @@ #include <linux/unwind_types.h> #include <linux/kallsyms.h> #include <asm/sections.h> +#include <asm/unwind_sframe.h> #include "sframe.h" #include "sframe_debug.h" @@ -294,7 +295,6 @@ static __always_inline int __read_fre(struct sframe_section *sec, unsigned long fre_addr, struct sframe_fre_internal *fre) { - unsigned char fde_type = SFRAME_V3_FDE_TYPE(fde->info2); unsigned char fde_pctype = SFRAME_V3_FDE_PCTYPE(fde->info); unsigned char fre_type = SFRAME_V3_FDE_FRE_TYPE(fde->info); unsigned char dataword_count, dataword_size; @@ -323,10 +323,6 @@ static __always_inline int __read_fre(struct sframe_section *sec, if (cur + (dataword_count * dataword_size) > sec->fres_end) return -EFAULT; - /* Flexible FDEs not supported */ - if (fde_type != SFRAME_FDE_TYPE_DEFAULT) - return -EFAULT; - fre->size = addr_size + 1 + (dataword_count * dataword_size); fre->ip_off = ip_off; fre->info = info; @@ -490,6 +486,73 @@ int sframe_find(unsigned long ip, struct unwind_frame *frame) return __sframe_find_module(ip, frame); } +#ifdef CONFIG_SFRAME_VALIDATION + +static int sframe_validate_section(struct sframe_section *sec) +{ + unsigned long prev_ip = 0; + unsigned int i; + + for (i = 0; i < sec->num_fdes; i++) { + struct sframe_fre_internal *fre, *prev_fre = NULL; + unsigned long ip, fre_addr; + struct sframe_fde_internal fde; + struct sframe_fre_internal fres[2]; + bool which = false; + unsigned int j; + int ret; + + ret = __read_fde(sec, i, &fde); + if (ret) { + dbg_sec(sec, "__read_fde(%u) failed\n", i); + return ret; + } + + ip = fde.func_addr; + if (ip <= prev_ip) { + dbg_sec(sec, "FDE %u not sorted\n", i); + return -EFAULT; + } + prev_ip = ip; + + fre_addr = sec->fres_start + fde.fres_off; + for (j = 0; j < fde.fres_num; j++) { + int ret; + + fre = which ? fres : fres + 1; + which = !which; + + ret = __read_fre(sec, &fde, fre_addr, fre); + if (ret) { + dbg_sec(sec, "FDE %u: __read_fre(%u) failed\n", i, j); + return ret; + } + ret = __read_fre_datawords(sec, &fde, fre); + if (ret) { + dbg_sec(sec, "FDE %u: __read_fre_datawords(%u) failed\n", i, j); + return ret; + } + + fre_addr += fre->size; + + if (prev_fre && fre->ip_off <= prev_fre->ip_off) { + dbg_sec(sec, "FDE %u: FRE %u not sorted\n", i, j); + return -EFAULT; + } + + prev_fre = fre; + } + } + + return 0; +} + +#else /* !CONFIG_SFRAME_VALIDATION */ + +static int sframe_validate_section(struct sframe_section *sec) { return 0; } + +#endif /* !CONFIG_SFRAME_VALIDATION */ + static int sframe_read_header(struct sframe_section *sec) { unsigned long header_end, fdes_start, fdes_end, fres_start, fres_end; @@ -551,6 +614,11 @@ void __init init_sframe_table(void) return; } + if (sframe_validate_section(&kernel_sfsec)) { + pr_warn("invalid vmlinux SFrame section\n"); + return; + } + sframe_init = true; dbg_print_header(&kernel_sfsec); } @@ -611,6 +679,11 @@ void sframe_module_init(struct module *mod, void *sframe, size_t sframe_size) } sframe_sort_fdes(sec); + if (sframe_validate_section(sec)) { + pr_warn("invalid SFrame section in module %s\n", mod->name); + return; + } + /* Ensure SFrame is initialized when sframe_find() happens */ WRITE_ONCE(mod->arch.sframe_init, true); dbg_print_header(sec); -- 2.55.0.1082.g2b9226bbc0-goog
