diff options
| author | Namhyung Kim <namhyung@kernel.org> | 2024-01-16 22:26:55 -0800 |
|---|---|---|
| committer | Namhyung Kim <namhyung@kernel.org> | 2024-01-22 12:08:20 -0800 |
| commit | 6fed025f119d229cf345aed2207d2922ed71871d (patch) | |
| tree | 71971ec6f49d6e01c10190e3014305d5ecd557ff | |
| parent | 5f7cdde843dd21c7228d9ae47d985086ce165985 (diff) | |
perf dwarf-aux: Add die_get_cfa()
The die_get_cfa() is to get frame base register and offset at the given
instruction address (pc). This info will be used to locate stack
variables which have location expression using DW_OP_fbreg.
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20240117062657.985479-8-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
| -rw-r--r-- | tools/perf/util/dwarf-aux.c | 68 | ||||
| -rw-r--r-- | tools/perf/util/dwarf-aux.h | 15 |
2 files changed, 82 insertions, 1 deletions
diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c index 7aa5fee0da19..3d42a8613869 100644 --- a/tools/perf/util/dwarf-aux.c +++ b/tools/perf/util/dwarf-aux.c @@ -1407,7 +1407,73 @@ Dwarf_Die *die_find_variable_by_addr(Dwarf_Die *sc_die, Dwarf_Addr pc, *offset = data.offset; return result; } -#endif +#endif /* HAVE_DWARF_GETLOCATIONS_SUPPORT */ + +#ifdef HAVE_DWARF_CFI_SUPPORT +static int reg_from_dwarf_op(Dwarf_Op *op) +{ + switch (op->atom) { + case DW_OP_reg0 ... DW_OP_reg31: + return op->atom - DW_OP_reg0; + case DW_OP_breg0 ... DW_OP_breg31: + return op->atom - DW_OP_breg0; + case DW_OP_regx: + case DW_OP_bregx: + return op->number; + default: + break; + } + return -1; +} + +static int offset_from_dwarf_op(Dwarf_Op *op) +{ + switch (op->atom) { + case DW_OP_reg0 ... DW_OP_reg31: + case DW_OP_regx: + return 0; + case DW_OP_breg0 ... DW_OP_breg31: + return op->number; + case DW_OP_bregx: + return op->number2; + default: + break; + } + return -1; +} + +/** + * die_get_cfa - Get frame base information + * @dwarf: a Dwarf info + * @pc: program address + * @preg: pointer for saved register + * @poffset: pointer for saved offset + * + * This function gets register and offset for CFA (Canonical Frame Address) + * by searching the CIE/FDE info. The CFA usually points to the start address + * of the current stack frame and local variables can be located using an offset + * from the CFA. The @preg and @poffset will be updated if it returns 0. + */ +int die_get_cfa(Dwarf *dwarf, u64 pc, int *preg, int *poffset) +{ + Dwarf_CFI *cfi; + Dwarf_Frame *frame = NULL; + Dwarf_Op *ops = NULL; + size_t nops; + + cfi = dwarf_getcfi(dwarf); + if (cfi == NULL) + return -1; + + if (!dwarf_cfi_addrframe(cfi, pc, &frame) && + !dwarf_frame_cfa(frame, &ops, &nops) && nops == 1) { + *preg = reg_from_dwarf_op(ops); + *poffset = offset_from_dwarf_op(ops); + return 0; + } + return -1; +} +#endif /* HAVE_DWARF_CFI_SUPPORT */ /* * die_has_loclist - Check if DW_AT_location of @vr_die is a location list diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h index 4e64caac6df8..f209f9162908 100644 --- a/tools/perf/util/dwarf-aux.h +++ b/tools/perf/util/dwarf-aux.h @@ -177,4 +177,19 @@ static inline Dwarf_Die *die_find_variable_by_addr(Dwarf_Die *sc_die __maybe_unu #endif /* HAVE_DWARF_GETLOCATIONS_SUPPORT */ +#ifdef HAVE_DWARF_CFI_SUPPORT + +/* Get the frame base information from CFA */ +int die_get_cfa(Dwarf *dwarf, u64 pc, int *preg, int *poffset); + +#else /* HAVE_DWARF_CFI_SUPPORT */ + +static inline int die_get_cfa(Dwarf *dwarf __maybe_unused, u64 pc __maybe_unused, + int *preg __maybe_unused, int *poffset __maybe_unused) +{ + return -1; +} + +#endif /* HAVE_DWARF_CFI_SUPPORT */ + #endif /* _DWARF_AUX_H */ |