From 180af1a5bdaf8d4964837a46a9fce8c3a7fd2d97 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Mon, 2 Oct 2023 17:57:47 +0100 Subject: scripts/faddr2line: Don't filter out non-function symbols from readelf As Josh points out in 20230724234734.zy67gm674vl3p3wv@treble: > Problem is, I think the kernel's symbol printing code prints the > nearest kallsyms symbol, and there are some valid non-FUNC code > symbols. For example, syscall_return_via_sysret. so we shouldn't be considering only 'FUNC'-type symbols in the output from readelf. Drop the function symbol type filtering from the faddr2line outer loop. Suggested-by: Josh Poimboeuf Reviewed-by: Nick Desaulniers Link: https://lore.kernel.org/r/20230724234734.zy67gm674vl3p3wv@treble Signed-off-by: Will Deacon Link: https://lore.kernel.org/r/20231002165750.1661-2-will@kernel.org Signed-off-by: Josh Poimboeuf --- scripts/faddr2line | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts') diff --git a/scripts/faddr2line b/scripts/faddr2line index 0e73aca4f908..a35a420d0f26 100755 --- a/scripts/faddr2line +++ b/scripts/faddr2line @@ -260,7 +260,7 @@ __faddr2line() { DONE=1 - done < <(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' | ${AWK} -v fn=$sym_name '$4 == "FUNC" && $8 == fn') + done < <(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' | ${AWK} -v fn=$sym_name '$8 == fn') } [[ $# -lt 2 ]] && usage -- cgit v1.2.3 From 86bf86e19d308a1dba41e5f1f7e8cc105a5efa49 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Mon, 2 Oct 2023 17:57:48 +0100 Subject: scripts/faddr2line: Use LLVM addr2line and readelf if LLVM=1 GNU utilities cannot necessarily parse objects built by LLVM, which can result in confusing errors when using 'faddr2line': $ CROSS_COMPILE=aarch64-linux-gnu- ./scripts/faddr2line vmlinux do_one_initcall+0xf4/0x260 aarch64-linux-gnu-addr2line: vmlinux: unknown type [0x13] section `.relr.dyn' aarch64-linux-gnu-addr2line: DWARF error: invalid or unhandled FORM value: 0x25 do_one_initcall+0xf4/0x260: aarch64-linux-gnu-addr2line: vmlinux: unknown type [0x13] section `.relr.dyn' aarch64-linux-gnu-addr2line: DWARF error: invalid or unhandled FORM value: 0x25 $x.73 at main.c:? Although this can be worked around by setting CROSS_COMPILE to "llvm=-", it's cleaner to follow the same syntax as the top-level Makefile and accept LLVM= as an indication to use the llvm- tools, optionally specifying their location or specific version number. Suggested-by: Masahiro Yamada Signed-off-by: Will Deacon Reviewed-by: Nick Desaulniers Link: https://lore.kernel.org/r/20231002165750.1661-3-will@kernel.org Signed-off-by: Josh Poimboeuf --- scripts/faddr2line | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) (limited to 'scripts') diff --git a/scripts/faddr2line b/scripts/faddr2line index a35a420d0f26..6b8206802157 100755 --- a/scripts/faddr2line +++ b/scripts/faddr2line @@ -58,8 +58,21 @@ die() { exit 1 } -READELF="${CROSS_COMPILE:-}readelf" -ADDR2LINE="${CROSS_COMPILE:-}addr2line" +UTIL_SUFFIX="" +if [[ "${LLVM:-}" == "" ]]; then + UTIL_PREFIX=${CROSS_COMPILE:-} +else + UTIL_PREFIX=llvm- + + if [[ "${LLVM}" == *"/" ]]; then + UTIL_PREFIX=${LLVM}${UTIL_PREFIX} + elif [[ "${LLVM}" == "-"* ]]; then + UTIL_SUFFIX=${LLVM} + fi +fi + +READELF="${UTIL_PREFIX}readelf${UTIL_SUFFIX}" +ADDR2LINE="${UTIL_PREFIX}addr2line${UTIL_SUFFIX}" AWK="awk" GREP="grep" -- cgit v1.2.3 From 60fd39af33d3f63c4c94bd06784ebdf0d883f5c9 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Mon, 2 Oct 2023 17:57:49 +0100 Subject: scripts/faddr2line: Skip over mapping symbols in output from readelf Mapping 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 these entries from readelf using a shell reimplementation of is_mapping_symbol(), so that the size of a symbol is calculated as a delta to the next symbol present in ksymtab. Suggested-by: Masahiro Yamada Signed-off-by: Will Deacon Reviewed-by: Nick Desaulniers Link: https://lore.kernel.org/r/20231002165750.1661-4-will@kernel.org Signed-off-by: Josh Poimboeuf --- scripts/faddr2line | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'scripts') diff --git a/scripts/faddr2line b/scripts/faddr2line index 6b8206802157..587415a52b6f 100755 --- a/scripts/faddr2line +++ b/scripts/faddr2line @@ -179,6 +179,11 @@ __faddr2line() { local cur_sym_elf_size=${fields[2]} local cur_sym_name=${fields[7]:-} + # is_mapping_symbol(cur_sym_name) + if [[ ${cur_sym_name} =~ ^(\.L|L0|\$) ]]; then + continue + fi + if [[ $cur_sym_addr = $sym_addr ]] && [[ $cur_sym_elf_size = $sym_elf_size ]] && [[ $cur_sym_name = $sym_name ]]; then -- cgit v1.2.3