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selftests/x86/fsgsbase: Test ptracer-induced GSBASE write with FSGSBASE

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This validates that GS and GSBASE are independently preserved in
ptracer commands.

Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Link: https://lkml.kernel.org/r/1557309753-24073-16-git-send-email-chang.seok.bae@intel.com
This commit is contained in:
Chang S. Bae 2019-05-08 03:02:30 -07:00 committed by Thomas Gleixner
parent 9ad75a0922
commit a87730cc3a
1 changed files with 9 additions and 2 deletions
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11
tools/testing/selftests/x86/fsgsbase.c
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@ -470,7 +470,7 @@ 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);
@ -486,6 +486,7 @@ 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
@ -496,8 +497,14 @@ static void test_ptrace_write_gsbase(void)
if (gs != 0x7) {
nerrs++;
printf("[FAIL]\tGS changed to %lx\n", gs);
} else if (have_fsgsbase && (base != 0xFF)) {
nerrs++;
printf("[FAIL]\tGSBASE changed to %lx\n", base);
} else {
printf("[OK]\tGS remained 0x7\n");
printf("[OK]\tGS remained 0x7 %s");
if (have_fsgsbase)
printf("and GSBASE changed to 0xFF");
printf("\n");
}
}