The run_readelf() function reads the entire output of readelf into a
single shell variable. For large object files with extensive debug
information, the size of this variable can exceed the system's
command-line argument length limit.
When this variable is subsequently passed to sed via `echo "${out}"`, it
triggers an "Argument list too long" error, causing the script to fail.
Fix this by redirecting the output of readelf to a temporary file
instead of a variable. The sed commands are then modified to read from
this file, avoiding the argument length limitation entirely.
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
The shebang `#!/bin/bash` assumes a fixed path for the bash interpreter.
This path does not exist on some systems, such as NixOS, causing the
script to fail.
Replace `/bin/bash` with the more portable `#!/usr/bin/env bash`.
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Force tools like readelf to use the POSIX/C locale by exporting LANG=C
This ensures ASCII-only output and avoids locale-specific
characters(e.g., UTF-8 symbols or translated strings), which could
break text processing utilities like sed in the script
Signed-off-by: John Wang <wangzq.jn@gmail.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This reverts commit c02904f05f.
Such commit assumed that only two symbols are relevant for the symbol
size calculation. However, this can lead to an incorrect symbol size
calculation when there are mapping symbols emitted by readelf.
For instance, when feeding 'update_irq_load_avg+0x1c/0x1c4', faddr2line
might need to process the following readelf lines:
784284: ffffffc0081cca30 428 FUNC GLOBAL DEFAULT 2 update_irq_load_avg
87319: ffffffc0081ccb0c 0 NOTYPE LOCAL DEFAULT 2 $x.62522
87321: ffffffc0081ccbdc 0 NOTYPE LOCAL DEFAULT 2 $x.62524
87323: ffffffc0081ccbe0 0 NOTYPE LOCAL DEFAULT 2 $x.62526
87325: ffffffc0081ccbe4 0 NOTYPE LOCAL DEFAULT 2 $x.62528
87327: ffffffc0081ccbe8 0 NOTYPE LOCAL DEFAULT 2 $x.62530
87329: ffffffc0081ccbec 0 NOTYPE LOCAL DEFAULT 2 $x.62532
87331: ffffffc0081ccbf0 0 NOTYPE LOCAL DEFAULT 2 $x.62534
87332: ffffffc0081ccbf4 0 NOTYPE LOCAL DEFAULT 2 $x.62535
783403: ffffffc0081ccbf4 424 FUNC GLOBAL DEFAULT 2 sched_pelt_multiplier
The symbol size of 'update_irq_load_avg' should be calculated with the
address of 'sched_pelt_multiplier', after skipping the mapping symbols
seen in between. However, the offending commit cuts the list short and
faddr2line incorrectly assumes 'update_irq_load_avg' is the last symbol
in the section, resulting in:
$ scripts/faddr2line vmlinux update_irq_load_avg+0x1c/0x1c4
skipping update_irq_load_avg address at 0xffffffc0081cca4c due to size mismatch (0x1c4 != 0x3ff9a59988)
no match for update_irq_load_avg+0x1c/0x1c4
After reverting the commit the issue is resolved:
$ scripts/faddr2line vmlinux update_irq_load_avg+0x1c/0x1c4
update_irq_load_avg+0x1c/0x1c4:
cpu_of at kernel/sched/sched.h:1109
(inlined by) update_irq_load_avg at kernel/sched/pelt.c:481
Fixes: c02904f05f ("scripts/faddr2line: Check only two symbols when calculating symbol size")
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Brian Johannesmeyer <bjohannesmeyer@gmail.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Rather than invoking a separate addr2line process for each address, invoke
a single addr2line coprocess, and pass each address to its stdin. Previous
work [0] applied a similar change to perf, leading to a ~60x speed-up [1].
If using an object file that is _not_ vmlinux, faddr2line passes a section
name argument to addr2line. Because we do not know until runtime which
section names will be passed to addr2line, we cannot apply this change to
non-vmlinux object files. Hence, it only applies to vmlinux.
[0] commit be8ecc57f1 ("perf srcline: Use long-running addr2line per
DSO")
[1] Link:
https://eighty-twenty.org/2021/09/09/perf-addr2line-speed-improvement
Signed-off-by: Brian Johannesmeyer <bjohannesmeyer@gmail.com>
Link: https://lore.kernel.org/r/20240415145538.1938745-6-bjohannesmeyer@gmail.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
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 <masahiroy@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20231002165750.1661-4-will@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
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 <masahiroy@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20231002165750.1661-3-will@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Commit 1d1a0e7c51 ("scripts/faddr2line: Fix overlapping text section
failures") can cause faddr2line to fail on ppc64le on some
distributions, while it works fine on other distributions. The failure
can be attributed to differences in the readelf output.
$ ./scripts/faddr2line vmlinux find_busiest_group+0x00
no match for find_busiest_group+0x00
On ppc64le, readelf adds the localentry tag before the symbol name on
some distributions, and adds the localentry tag after the symbol name on
other distributions. This problem has been discussed previously:
https://lore.kernel.org/bpf/20191211160133.GB4580@calabresa/
This problem can be overcome by filtering out the localentry tags in the
readelf output. Similar fixes are already present in the kernel by way
of the following commits:
1fd6cee127 ("libbpf: Fix VERSIONED_SYM_COUNT number parsing")
aa915931ac ("libbpf: Fix readelf output parsing for Fedora")
[jpoimboe: rework commit log]
Fixes: 1d1a0e7c51 ("scripts/faddr2line: Fix overlapping text section failures")
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Link: https://lore.kernel.org/r/20220927075211.897152-1-srikar@linux.vnet.ibm.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
If a function lives in a section other than .text, but .text also exists
in the object, faddr2line may wrongly assume .text. This can result in
comically wrong output. For example:
$ scripts/faddr2line vmlinux.o enter_from_user_mode+0x1c
enter_from_user_mode+0x1c/0x30:
find_next_bit at /home/jpoimboe/git/linux/./include/linux/find.h:40
(inlined by) perf_clear_dirty_counters at /home/jpoimboe/git/linux/arch/x86/events/core.c:2504
Fix it by passing the section name to addr2line, unless the object file
is vmlinux, in which case the symbol table uses absolute addresses.
Fixes: 1d1a0e7c51 ("scripts/faddr2line: Fix overlapping text section failures")
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/7d25bc1408bd3a750ac26e60d2f2815a5f4a8363.1654130536.git.jpoimboe@kernel.org
There have been some recent reports of faddr2line failures:
$ scripts/faddr2line sound/soundcore.ko sound_devnode+0x5/0x35
bad symbol size: base: 0x0000000000000000 end: 0x0000000000000000
$ ./scripts/faddr2line vmlinux.o enter_from_user_mode+0x24
bad symbol size: base: 0x0000000000005fe0 end: 0x0000000000005fe0
The problem is that faddr2line is based on 'nm', which has a major
limitation: it doesn't know how to distinguish between different text
sections. So if an offset exists in multiple text sections in the
object, it may fail.
Rewrite faddr2line to be section-aware, by basing it on readelf.
Fixes: 67326666e2 ("scripts: add script for translating stack dump function offsets")
Reported-by: Kaiwan N Billimoria <kaiwan.billimoria@gmail.com>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/29ff99f86e3da965b6e46c1cc2d72ce6528c17c3.1652382321.git.jpoimboe@kernel.org
Commit 6870c0165f ("scripts/faddr2line: show the code context")
radically altered the output format of the faddr2line tool. And while
the new list output format might have merit it broke my vim usage and
was hard to read.
Make the new format optional; using a '--list' argument and attempt to
make the output slightly easier to read by adding a little whitespace to
separate the different files and explicitly mark the line in question.
Cc: Changbin Du <changbin.du@intel.com>
Fixes: 6870c0165f ("scripts/faddr2line: show the code context")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
