Messages in this thread Patch in this message | | | From | Will Deacon <> | Subject | [PATCH 1/2] scripts/faddr2line: Ignore non-function symbols in readelf output | Date | Mon, 24 Jul 2023 18:45:16 +0100 |
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Non-function symbols emitted in the readelf output can confuse the 'faddr2line' symbol size calculation, resulting in the erroneous rejection of valid offsets. This is especially prevalent when building an arm64 kernel with CONFIG_CFI_CLANG=y, where most functions are prefixed with a 32-bit data value in a '$d.n' section. For example:
447538: ffff800080014b80 548 FUNC GLOBAL DEFAULT 2 do_one_initcall 104: ffff800080014c74 0 NOTYPE LOCAL DEFAULT 2 $x.73 106: ffff800080014d30 0 NOTYPE LOCAL DEFAULT 2 $x.75 111: ffff800080014da4 0 NOTYPE LOCAL DEFAULT 2 $d.78 112: ffff800080014da8 0 NOTYPE LOCAL DEFAULT 2 $x.79 36: ffff800080014de0 200 FUNC LOCAL DEFAULT 2 run_init_process
Adding a warning to do_one_initcall() results in:
| WARNING: CPU: 0 PID: 1 at init/main.c:1236 do_one_initcall+0xf4/0x260
Which 'faddr2line' refuses to accept:
$ ./scripts/faddr2line vmlinux do_one_initcall+0xf4/0x260 skipping do_one_initcall address at 0xffff800080014c74 due to size mismatch (0x260 != 0x224) no match for do_one_initcall+0xf4/0x260
Filter out entries from readelf that are not "FUNC" type, so that the size of a symbol is calculated as a delta to the next function address.
Cc: Josh Poimboeuf <jpoimboe@kernel.org> Cc: John Stultz <jstultz@google.com> Signed-off-by: Will Deacon <will@kernel.org> --- scripts/faddr2line | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/scripts/faddr2line b/scripts/faddr2line index 0e73aca4f908..60368a1cdaed 100755 --- a/scripts/faddr2line +++ b/scripts/faddr2line @@ -179,7 +179,7 @@ __faddr2line() { found=2 break fi - done < <(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2) + done < <(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' | ${AWK} -v sec=$sym_sec '$4 == "FUNC" && $7 == sec' | sort --key=2) if [[ $found = 0 ]]; then warn "can't find symbol: sym_name: $sym_name sym_sec: $sym_sec sym_addr: $sym_addr sym_elf_size: $sym_elf_size" -- 2.41.0.487.g6d72f3e995-goog
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