x86_64: Suppress false positive valgrind error
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Commit Message
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.
---
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(-)
create mode 100644 sysdeps/x86_64/tst-valgrind-smoke.supp
Comments
On Sun, Feb 25, 2024 at 4:03 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> 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.
> ---
> 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(-)
> create mode 100644 sysdeps/x86_64/tst-valgrind-smoke.supp
>
> diff --git a/elf/Makefile b/elf/Makefile
> index 36c04baf02..9d7190f708 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -616,7 +616,8 @@ 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 145f25e7f6..07b4a532ae 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
> +}
> --
> 2.43.2
>
LGTM
Reviewed-by: Sunil K Pandey <skpgkp2@gmail.com>
@@ -616,7 +616,8 @@ 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)
@@ -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}"
@@ -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)
new file mode 100644
@@ -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
+}