On 5/28/20 2:14 PM, Sasha Levin wrote:
From: "Chang S. Bae" <[email protected]>
This validates that GS selector and base are independently preserved in
ptrace commands.
Suggested-by: Andy Lutomirski <[email protected]>
Signed-off-by: Chang S. Bae <[email protected]>
Reviewed-by: Tony Luck <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Andi Kleen <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
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
