selftests/x86/fsgsbase: Test ptracer-induced GSBASE write with FSGSBASE (a87730cc) · Commits · 戴 / test

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

tools/testing/selftests/x86/fsgsbase.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -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");
		}
		}