summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--arch/x86/kernel/ptrace.c14
-rw-r--r--tools/testing/selftests/x86/fsgsbase.c22
2 files changed, 16 insertions, 20 deletions
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 71691a8310e7..0fdbe89d0754 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -369,12 +369,22 @@ static int putreg(struct task_struct *child,
case offsetof(struct user_regs_struct,fs_base):
if (value >= TASK_SIZE_MAX)
return -EIO;
- x86_fsbase_write_task(child, value);
+ /*
+ * When changing the FS base, use do_arch_prctl_64()
+ * to set the index to zero and to set the base
+ * as requested.
+ */
+ if (child->thread.fsbase != value)
+ return do_arch_prctl_64(child, ARCH_SET_FS, value);
return 0;
case offsetof(struct user_regs_struct,gs_base):
+ /*
+ * Exactly the same here as the %fs handling above.
+ */
if (value >= TASK_SIZE_MAX)
return -EIO;
- x86_gsbase_write_task(child, value);
+ if (child->thread.gsbase != value)
+ return do_arch_prctl_64(child, ARCH_SET_GS, value);
return 0;
#endif
}
diff --git a/tools/testing/selftests/x86/fsgsbase.c b/tools/testing/selftests/x86/fsgsbase.c
index 5ab4c60c100e..15a329da59fa 100644
--- a/tools/testing/selftests/x86/fsgsbase.c
+++ b/tools/testing/selftests/x86/fsgsbase.c
@@ -489,25 +489,11 @@ static void test_ptrace_write_gsbase(void)
* selector value is changed or not by the GSBASE write in
* a ptracer.
*/
- if (gs != *shared_scratch) {
- nerrs++;
- printf("[FAIL]\tGS changed to %lx\n", gs);
-
- /*
- * On older kernels, poking a nonzero value into the
- * base would zero the selector. On newer kernels,
- * this behavior has changed -- poking the base
- * changes only the base and, if FSGSBASE is not
- * available, this may have no effect.
- */
- if (gs == 0)
- printf("\tNote: this is expected behavior on older kernels.\n");
- } else if (have_fsgsbase && (base != 0xFF)) {
- nerrs++;
- printf("[FAIL]\tGSBASE changed to %lx\n", base);
+ if (gs == 0 && base == 0xFF) {
+ printf("[OK]\tGS was reset as expected\n");
} else {
- printf("[OK]\tGS remained 0x%hx%s", *shared_scratch, have_fsgsbase ? " and GSBASE changed to 0xFF" : "");
- printf("\n");
+ nerrs++;
+ printf("[FAIL]\tGS=0x%lx, GSBASE=0x%lx (should be 0, 0xFF)\n", gs, base);
}
}