Messages in this thread | | | Subject | Re: [PATCH v13 16/16] selftests/x86/fsgsbase: Test ptracer-induced GS base write with FSGSBASE | From | Shuah Khan <> | Date | Fri, 29 May 2020 08:42:16 -0600 |
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On 5/28/20 2:14 PM, Sasha Levin wrote: > From: "Chang S. Bae" <chang.seok.bae@intel.com> > > This validates that GS selector and base are independently preserved in > ptrace commands. > > Suggested-by: Andy Lutomirski <luto@kernel.org> > Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> > Reviewed-by: Tony Luck <tony.luck@intel.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Borislav Petkov <bp@alien8.de> > Cc: Andy Lutomirski <luto@kernel.org> > Cc: H. Peter Anvin <hpa@zytor.com> > Cc: Dave Hansen <dave.hansen@intel.com> > Cc: Tony Luck <tony.luck@intel.com> > Cc: Andi Kleen <ak@linux.intel.com> > Signed-off-by: Sasha Levin <sashal@kernel.org> > --- > tools/testing/selftests/x86/fsgsbase.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/x86/fsgsbase.c b/tools/testing/selftests/x86/fsgsbase.c > index 950a48b2e366..9a4349813a30 100644 > --- a/tools/testing/selftests/x86/fsgsbase.c > +++ b/tools/testing/selftests/x86/fsgsbase.c > @@ -465,7 +465,7 @@ static void test_ptrace_write_gsbase(void) > wait(&status); > > if (WSTOPSIG(status) == SIGTRAP) { > - unsigned long gs; > + unsigned long gs, base; > unsigned long gs_offset = USER_REGS_OFFSET(gs); > unsigned long base_offset = USER_REGS_OFFSET(gs_base); > > @@ -481,6 +481,7 @@ static void test_ptrace_write_gsbase(void) > err(1, "PTRACE_POKEUSER"); > > gs = ptrace(PTRACE_PEEKUSER, child, gs_offset, NULL); > + base = ptrace(PTRACE_PEEKUSER, child, base_offset, NULL); > > /* > * In a non-FSGSBASE system, the nonzero selector will load > @@ -501,8 +502,14 @@ static void test_ptrace_write_gsbase(void) > */ > if (gs == 0) > printf("\tNote: this is expected behavior on older kernels.\n");
I know this hasn't changed. Please clarify what is "this" in this message.
> + } else if (have_fsgsbase && (base != 0xFF)) { > + nerrs++; > + printf("[FAIL]\tGSBASE changed to %lx\n", base); > } else { > - printf("[OK]\tGS remained 0x%hx\n", *shared_scratch); > + printf("[OK]\tGS remained 0x%hx", *shared_scratch); > + if (have_fsgsbase) > + printf(" and GSBASE changed to 0xFF"); > + printf("\n"); > } > } > >
thanks, -- Shuah
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