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authorDmitry Safonov <dsafonov@virtuozzo.com>2017-02-13 13:13:36 +0300
committerIngo Molnar <mingo@kernel.org>2017-03-01 12:24:56 +0300
commit2a4d0c627f5374f365a873dea4e10ae0bb437680 (patch)
treef3ca0fb9ee40b75e6687e7b08d6ea7330a85b87f /tools/testing/selftests/x86/ptrace_syscall.c
parent11277aabcbbe13916151af897d29a5e9f71ca73f (diff)
downloadlinux-2a4d0c627f5374f365a873dea4e10ae0bb437680.tar.xz
x86/selftests: Add clobbers for int80 on x86_64
Kernel erases R8..R11 registers prior returning to userspace from int80: https://lkml.org/lkml/2009/10/1/164 GCC can reuse these registers and doesn't expect them to change during syscall invocation. I met this kind of bug in CRIU once GCC 6.1 and CLANG stored local variables in those registers and the kernel zerofied them during syscall: https://github.com/xemul/criu/commit/990d33f1a1cdd17bca6c2eb059ab3be2564f7fa2 By that reason I suggest to add those registers to clobbers in selftests. Also, as noted by Andy - removed unneeded clobber for flags in INT $0x80 inline asm. Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: 0x7f454c46@gmail.com Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bp@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Shuah Khan <shuah@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kselftest@vger.kernel.org Link: http://lkml.kernel.org/r/20170213101336.20486-1-dsafonov@virtuozzo.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'tools/testing/selftests/x86/ptrace_syscall.c')
-rw-r--r--tools/testing/selftests/x86/ptrace_syscall.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/tools/testing/selftests/x86/ptrace_syscall.c b/tools/testing/selftests/x86/ptrace_syscall.c
index b037ce9cf116..eaea92439708 100644
--- a/tools/testing/selftests/x86/ptrace_syscall.c
+++ b/tools/testing/selftests/x86/ptrace_syscall.c
@@ -58,7 +58,8 @@ static void do_full_int80(struct syscall_args32 *args)
asm volatile ("int $0x80"
: "+a" (args->nr),
"+b" (args->arg0), "+c" (args->arg1), "+d" (args->arg2),
- "+S" (args->arg3), "+D" (args->arg4), "+r" (bp));
+ "+S" (args->arg3), "+D" (args->arg4), "+r" (bp)
+ : : "r8", "r9", "r10", "r11");
args->arg5 = bp;
#else
sys32_helper(args, int80_and_ret);