From: Jens Remus <[email protected]> __find_fre() performs linear search for a matching SFrame FRE for a given IP. For that purpose it uses __read_fre(), which reads the whole FRE. That is the variable-size FRE structure as well as the trailing variable-length array of variable-size data words. For the search logic to skip over the FRE it would be sufficient to read the variable-size FRE structure only, which includes the count and size of data words.
Add fields to struct sframe_fre_internal to store the FRE data word's address, count, and size. Change __read_fre() to read the variable- size FRE structure only and populate those new fields. Change __read_fre_datawords() to use those new fields. Change __find_fre() to use __read_fre_datawords() to read the FRE data words only after a matching FRE has been found. [ Dylan Hatch: Adapt for in-kernel unwinding without flexible FDEs. ] Reviewed-by: Indu Bhagat <[email protected]> Signed-off-by: Jens Remus <[email protected]> Signed-off-by: Steven Rostedt <[email protected]> Signed-off-by: Dylan Hatch <[email protected]> --- This patch is adapted from commit 745489faa10c ("unwind_user/sframe: Separate reading of FRE from reading of FRE data words") and squashes changes from: - fdaf91d4fc0d ("unwind_user/sframe: Add support for SFrame V3 flexible FDEs") - 79313210e44e ("unwind_user/sframe: Add support for outermost frame indication") all of which are from Steven's sframe/core branch. Changes include: - Drop support for flexible FDEs (SFRAME_FDE_TYPE_FLEX). - Sqaush in creation of __read_default_fre_datawords() and __read_fre_datawords(). - Squash in outermost frame handling logic. - Deferred sframe_validate_section() changes to a later patch. --- kernel/unwind/sframe.c | 97 +++++++++++++++++++++++++++++++----------- 1 file changed, 73 insertions(+), 24 deletions(-) diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index f3975c7e89493..9aac703f7ce6e 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -36,6 +36,9 @@ struct sframe_fre_internal { s32 ra_off; s32 fp_off; u8 info; + unsigned long dw_addr; + unsigned char dw_count; + unsigned char dw_size; }; static __always_inline unsigned char fre_type_to_size(unsigned char fre_type) @@ -179,6 +182,67 @@ static __always_inline int __find_fde(struct sframe_section *sec, s32 : GET_SIGNED_AND_INC(to, from, size), \ s64 : GET_SIGNED_AND_INC(to, from, size)) +static __always_inline int +__read_default_fre_datawords(struct sframe_section *sec, + struct sframe_fde_internal *fde, + struct sframe_fre_internal *fre) +{ + unsigned char dataword_count = fre->dw_count; + unsigned char dataword_size = fre->dw_size; + unsigned long cur = fre->dw_addr; + s32 cfa_off, ra_off, fp_off; + + GET_AND_INC(cfa_off, cur, dataword_size); + dataword_count--; + + ra_off = sec->ra_off; + if (!ra_off && dataword_count) { + dataword_count--; + GET_AND_INC(ra_off, cur, dataword_size); + } + + fp_off = sec->fp_off; + if (!fp_off && dataword_count) { + dataword_count--; + GET_AND_INC(fp_off, cur, dataword_size); + } + + if (dataword_count) + return -EFAULT; + + fre->cfa_off = cfa_off; + fre->ra_off = ra_off; + fre->fp_off = fp_off; + + return 0; +} + +static __always_inline int +__read_fre_datawords(struct sframe_section *sec, + struct sframe_fde_internal *fde, + struct sframe_fre_internal *fre) +{ + unsigned char fde_type = SFRAME_V3_FDE_TYPE(fde->info2); + unsigned char dataword_count = fre->dw_count; + + if (!dataword_count) { + /* A FRE without data words indicates an outermost frame. */ + fre->cfa_off = 0; + fre->ra_off = 0; + fre->fp_off = 0; + + return 0; + } + + switch (fde_type) { + case SFRAME_FDE_TYPE_DEFAULT: + return __read_default_fre_datawords(sec, fde, fre); + /* Flexible FDEs not supported */ + default: + return -EFAULT; + } +} + static __always_inline int __read_fre(struct sframe_section *sec, struct sframe_fde_internal *fde, unsigned long fre_addr, @@ -188,7 +252,6 @@ static __always_inline int __read_fre(struct sframe_section *sec, 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; - s32 cfa_off, ra_off, fp_off; unsigned long cur = fre_addr; unsigned char addr_size; u32 ip_off; @@ -208,7 +271,7 @@ static __always_inline int __read_fre(struct sframe_section *sec, GET_AND_INC(info, cur, 1); dataword_count = SFRAME_V3_FRE_DATAWORD_COUNT(info); dataword_size = dataword_size_enum_to_size(SFRAME_V3_FRE_DATAWORD_SIZE(info)); - if (!dataword_size || !dataword_count) + if (!dataword_size) return -EFAULT; if (cur + (dataword_count * dataword_size) > sec->fres_end) @@ -219,30 +282,11 @@ static __always_inline int __read_fre(struct sframe_section *sec, return -EFAULT; fre->size = addr_size + 1 + (dataword_count * dataword_size); - - GET_AND_INC(cfa_off, cur, dataword_size); - dataword_count--; - - ra_off = sec->ra_off; - if (!ra_off && dataword_count) { - dataword_count--; - GET_AND_INC(ra_off, cur, dataword_size); - } - - fp_off = sec->fp_off; - if (!fp_off && dataword_count) { - dataword_count--; - GET_AND_INC(fp_off, cur, dataword_size); - } - - if (dataword_count) - return -EFAULT; - fre->ip_off = ip_off; - fre->cfa_off = cfa_off; - fre->ra_off = ra_off; - fre->fp_off = fp_off; fre->info = info; + fre->dw_addr = cur; + fre->dw_count = dataword_count; + fre->dw_size = dataword_size; return 0; } @@ -292,6 +336,7 @@ static __always_inline int __find_fre(struct sframe_section *sec, bool which = false; unsigned int i; u32 ip_off; + int ret; ip_off = ip - fde->func_addr; @@ -332,6 +377,10 @@ static __always_inline int __find_fre(struct sframe_section *sec, return -EINVAL; fre = prev_fre; + ret = __read_fre_datawords(sec, fde, fre); + if (ret) + return ret; + if (sframe_init_cfa_rule_data(&frame->cfa, fre->info, fre->cfa_off)) return -EINVAL; -- 2.55.0.1082.g2b9226bbc0-goog
