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Re: valgrind support for glibc master
- From: Mark Wielaard <mark at klomp dot org>
- To: Siddhesh Poyarekar <siddhesh at gotplt dot org>
- Cc: Florian Weimer <fweimer at redhat dot com>, GNU C Library <libc-alpha at sourceware dot org>, The GNU C Library support for Fedora <glibc at lists dot fedoraproject dot org>
- Date: Thu, 22 Jun 2017 13:39:31 +0200
- Subject: Re: valgrind support for glibc master
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On Thu, 2017-06-22 at 16:58 +0530, Siddhesh Poyarekar wrote:
> On Thursday 22 June 2017 04:44 PM, Florian Weimer wrote:
> > glibc performs a quick test run using valgrind as part of the build process.
> > Lately, this started crashing:
> > + elf/ld.so --library-path .:elf:nptl:dlfcn /usr/bin/valgrind elf/ld.so
> > --library-path .:elf:nptl:dlfcn /usr/bin/true
> > ==924== Memcheck, a memory error detector
> > ==924== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
> > ==924== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
> > ==924== Command: elf/ld.so --library-path .:elf:nptl:dlfcn /usr/bin/true
> > ==924==
> > ARM64 front end: branch_etc
> > disInstr(arm64): unhandled instruction 0xD5380000
> > disInstr(arm64): 1101'0101 0011'1000 0000'0000 0000'0000
> > ==924== valgrind: Unrecognised instruction at address 0x11f548.
> > ==924== at 0x11F548: init_cpu_features (cpu-features.c:32)
> > ==924== by 0x11F548: dl_platform_init (dl-machine.h:241)
> > ==924== by 0x11F548: _dl_sysdep_start (dl-sysdep.c:231)
> > ==924== by 0x10981B: _dl_start_final (rtld.c:412)
> > ==924== by 0x109AAB: _dl_start (rtld.c:520)
> > ==924== by 0x108F47: ??? (in
> > /builddir/build/BUILD/glibc-2.25-545-g9649350/build-aarch64-redhat-linux/elf/ld.so)
> > The line in question is:
> > asm volatile ("mrs %0, midr_el1" : "=r"(id));
> > That seems to match the instruction bit pattern, too. There is a check
> > around it:
> This needs a valgrind patch to identify reading midr_el1 (in
> VEX/priv/guest_arm64_toIR.c AFAICT), which is trapped and emulated by
> the kernel since 4.11.
> Is someone already working on this or would you like me to do this?
As far as I know, nobody is working on this yet. So if you can then
please do. Even if you don't know how to fix the valgrind side just
filing a bug report with the expected behavior of the missing emulation
would be appreciated.
Maybe valgrind should just filter out the HWCAP_CPUID? Trying to figure
out why this started failing. I assume 4.10 didn't set that, but that it
is now set by the 4.11 kernel?