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From: H.J. Lu <hjl@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc] x86_64: Suppress false positive valgrind error Date: Wed, 28 Feb 2024 21:41:14 +0000 (GMT) [thread overview] Message-ID: <20240228214114.20E4A3858CD1@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a1735e0aa858f0c8b15e5ee9975bff4279423680 commit a1735e0aa858f0c8b15e5ee9975bff4279423680 Author: H.J. Lu <hjl.tools@gmail.com> Date: Sun Feb 25 16:03:26 2024 -0800 x86_64: Suppress false positive valgrind error When strcmp-avx2.S is used as the default, elf/tst-valgrind-smoke fails with ==1272761== Conditional jump or move depends on uninitialised value(s) ==1272761== at 0x4022C98: strcmp (strcmp-avx2.S:462) ==1272761== by 0x400B05B: _dl_name_match_p (dl-misc.c:75) ==1272761== by 0x40085F3: _dl_map_object (dl-load.c:1966) ==1272761== by 0x401AEA4: map_doit (rtld.c:644) ==1272761== by 0x4001488: _dl_catch_exception (dl-catch.c:237) ==1272761== by 0x40015AE: _dl_catch_error (dl-catch.c:256) ==1272761== by 0x401B38F: do_preload (rtld.c:816) ==1272761== by 0x401C116: handle_preload_list (rtld.c:892) ==1272761== by 0x401EDF5: dl_main (rtld.c:1842) ==1272761== by 0x401A79E: _dl_sysdep_start (dl-sysdep.c:140) ==1272761== by 0x401BEEE: _dl_start_final (rtld.c:494) ==1272761== by 0x401BEEE: _dl_start (rtld.c:581) ==1272761== by 0x401AD87: ??? (in */elf/ld.so) The assembly codes are: 0x0000000004022c80 <+144>: vmovdqu 0x20(%rdi),%ymm0 0x0000000004022c85 <+149>: vpcmpeqb 0x20(%rsi),%ymm0,%ymm1 0x0000000004022c8a <+154>: vpcmpeqb %ymm0,%ymm15,%ymm2 0x0000000004022c8e <+158>: vpandn %ymm1,%ymm2,%ymm1 0x0000000004022c92 <+162>: vpmovmskb %ymm1,%ecx 0x0000000004022c96 <+166>: inc %ecx => 0x0000000004022c98 <+168>: jne 0x4022c32 <strcmp+66> strcmp-avx2.S has 32-byte vector loads of strings which are shorter than 32 bytes: (gdb) p (char *) ($rdi + 0x20) $6 = 0x1ffeffea20 "memcheck-amd64-linux.so" (gdb) p (char *) ($rsi + 0x20) $7 = 0x4832640 "core-amd64-linux.so" (gdb) call (int) strlen ((char *) ($rsi + 0x20)) $8 = 19 (gdb) call (int) strlen ((char *) ($rdi + 0x20)) $9 = 23 (gdb) It triggers the valgrind error. The above code is safe since the loads don't cross the page boundary. Update tst-valgrind-smoke.sh to accept an optional suppression file and pass a suppression file to valgrind when strcmp-avx2.S is the default implementation of strcmp. Reviewed-by: Sunil K Pandey <skpgkp2@gmail.com> Diff: --- elf/Makefile | 3 ++- elf/tst-valgrind-smoke.sh | 5 +++-- sysdeps/x86_64/Makefile | 6 ++++++ sysdeps/x86_64/tst-valgrind-smoke.supp | 17 +++++++++++++++++ 4 files changed, 28 insertions(+), 3 deletions(-) diff --git a/elf/Makefile b/elf/Makefile index 02dc476e27..f0439ef634 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -617,7 +617,8 @@ tests-special += $(objpfx)tst-valgrind-smoke.out endif $(objpfx)tst-valgrind-smoke.out: tst-valgrind-smoke.sh $(objpfx)ld.so $(objpfx)valgrind-test $(SHELL) $< $(objpfx)ld.so $(rtlddir)/$(rtld-installed-name) '$(test-wrapper-env)' \ - '$(run-program-env)' '$(rpath-link)' $(objpfx)valgrind-test > $@; $(evaluate-test) + '$(run-program-env)' '$(rpath-link)' $(objpfx)valgrind-test \ + '$(valgrind-suppressions-tst-valgrind-smoke)' > $@; $(evaluate-test) tests += $(tests-execstack-$(have-z-execstack)) ifeq ($(run-built-tests),yes) diff --git a/elf/tst-valgrind-smoke.sh b/elf/tst-valgrind-smoke.sh index e33b2fa1d7..7d0ceac6b1 100644 --- a/elf/tst-valgrind-smoke.sh +++ b/elf/tst-valgrind-smoke.sh @@ -25,6 +25,7 @@ test_wrapper_env="$3" run_program_env="$4" library_path="$5" test_prog="$6" +valgrind_suppressions="$7" # Test whether valgrind is available in the test # environment. If not, skip the test. @@ -34,7 +35,7 @@ ${test_wrapper_env} ${run_program_env} \ # Test valgrind works with the system ld.so in the test environment /bin/sh -c \ "${test_wrapper_env} ${run_program_env} \ - valgrind -q --error-exitcode=1 \ + valgrind -q --error-exitcode=1 ${valgrind_suppressions} \ ${system_rtld} /bin/echo ${system_rtld}" || exit 77 # Finally the actual test inside the test environment, @@ -42,5 +43,5 @@ ${test_wrapper_env} ${run_program_env} \ # the smoke test under valgrind. /bin/sh -c \ "${test_wrapper_env} ${run_program_env} \ - valgrind -q --error-exitcode=1 \ + valgrind -q --error-exitcode=1 ${valgrind_suppressions} \ ${rtld} --library-path ${library_path} ${test_prog} ${rtld}" diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile index 9337e95093..66b21954f3 100644 --- a/sysdeps/x86_64/Makefile +++ b/sysdeps/x86_64/Makefile @@ -211,6 +211,12 @@ tst-plt-rewrite2-ENV = GLIBC_TUNABLES=glibc.cpu.plt_rewrite=2 $(objpfx)tst-plt-rewrite2: $(objpfx)tst-plt-rewritemod2.so endif +# Check if ISA level is 3 or above. +ifneq (,$(filter $(have-x86-isa-level),$(x86-isa-level-3-or-above))) +valgrind-suppressions-tst-valgrind-smoke = \ + --suppressions=$(..)sysdeps/x86_64/tst-valgrind-smoke.supp +endif + endif # $(subdir) == elf ifeq ($(subdir),csu) diff --git a/sysdeps/x86_64/tst-valgrind-smoke.supp b/sysdeps/x86_64/tst-valgrind-smoke.supp new file mode 100644 index 0000000000..533c2deaff --- /dev/null +++ b/sysdeps/x86_64/tst-valgrind-smoke.supp @@ -0,0 +1,17 @@ +{ + False positive at strcmp-avx2.S:462 + Memcheck:Cond + fun:strcmp + fun:_dl_name_match_p + fun:_dl_map_object + fun:map_doit + fun:_dl_catch_exception + fun:_dl_catch_error + fun:do_preload + fun:handle_preload_list + fun:dl_main + fun:_dl_sysdep_start + fun:_dl_start_final + fun:_dl_start + obj:*/elf/ld.so +}
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