The .sframe in kernel modules is built without SFRAME_F_FDE_SORTED set. In order to allow sframe PC lookup in modules, add a code path to handle unsorted FDE tables by doing a simple linear search.
Reviewed-by: Jens Remus <[email protected]> Signed-off-by: Dylan Hatch <[email protected]> --- include/linux/sframe.h | 1 + kernel/unwind/sframe.c | 45 +++++++++++++++++++++++++++++++++++++----- 2 files changed, 41 insertions(+), 5 deletions(-) diff --git a/include/linux/sframe.h b/include/linux/sframe.h index 5b7341b61a7c..8ae31ed36226 100644 --- a/include/linux/sframe.h +++ b/include/linux/sframe.h @@ -28,6 +28,7 @@ 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; diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index 430bff9533ee..dcf4deb378dc 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -176,9 +176,35 @@ static __always_inline int __read_fde(struct sframe_section *sec, return -EFAULT; } -static __always_inline int __find_fde(struct sframe_section *sec, - unsigned long ip, - struct sframe_fde_internal *fde) +static __always_inline int __find_fde_unsorted(struct sframe_section *sec, + unsigned long ip, + struct sframe_fde_internal *fde) +{ + struct sframe_fde_v3 *cur, *start, *end; + + start = (struct sframe_fde_v3 *)sec->fdes_start; + end = start + sec->num_fdes; + + for (cur = start; cur < end; cur++) { + s64 func_off; + u32 func_size; + unsigned long func_addr; + + DATA_GET(sec, func_off, &cur->func_start_off, s64, Efault); + DATA_GET(sec, func_size, &cur->func_size, u32, Efault); + func_addr = (unsigned long)cur + func_off; + + if (ip >= func_addr && ip < func_addr + func_size) + return __read_fde(sec, cur - start, fde); + } + return -EINVAL; +Efault: + return -EFAULT; +} + +static __always_inline int __find_fde_sorted(struct sframe_section *sec, + unsigned long ip, + struct sframe_fde_internal *fde) { unsigned long func_addr_low = 0, func_addr_high = ULONG_MAX; struct sframe_fde_v3 *first, *low, *high, *found = NULL; @@ -233,6 +259,15 @@ static __always_inline int __find_fde(struct sframe_section *sec, return -EFAULT; } +static __always_inline int __find_fde(struct sframe_section *sec, + unsigned long ip, + struct sframe_fde_internal *fde) +{ + if (sec->fdes_sorted) + return __find_fde_sorted(sec, ip, fde); + return __find_fde_unsorted(sec, ip, fde); +} + #define ____GET_INC(sec, to, from, type, label) \ ({ \ type __to; \ @@ -657,7 +692,7 @@ static int sframe_validate_section(struct sframe_section *sec) return ret; ip = fde.func_addr; - if (ip <= prev_ip) { + if (sec->fdes_sorted && ip <= prev_ip) { dbg_sec("fde %u not sorted\n", i); return -EFAULT; } @@ -736,7 +771,6 @@ 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) { dbg_sec("bad/unsupported sframe header\n"); @@ -766,6 +800,7 @@ 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; -- 2.54.0.545.g6539524ca2-goog
