Merge tag 'x86_core_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 core updates from Borislav Petkov:

 - Do not #GP on userspace use of CLI/STI but pretend it was a NOP to
   keep old userspace from breaking. Adjust the corresponding iopl
   selftest to that.

 - Improve stack overflow warnings to say which stack got overflowed and
   raise the exception stack sizes to 2 pages since overflowing the
   single page of exception stack is very easy to do nowadays with all
   the tracing machinery enabled. With that, rip out the custom mapping
   of AMD SEV's too.

 - A bunch of changes in preparation for FGKASLR like supporting more
   than 64K section headers in the relocs tool, correct ORC lookup table
   size to cover the whole kernel .text and other adjustments.

* tag 'x86_core_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  selftests/x86/iopl: Adjust to the faked iopl CLI/STI usage
  vmlinux.lds.h: Have ORC lookup cover entire _etext - _stext
  x86/boot/compressed: Avoid duplicate malloc() implementations
  x86/boot: Allow a "silent" kaslr random byte fetch
  x86/tools/relocs: Support >64K section headers
  x86/sev: Make the #VC exception stacks part of the default stacks storage
  x86: Increase exception stack sizes
  x86/mm/64: Improve stack overflow warnings
  x86/iopl: Fake iopl(3) CLI/STI usage

1 files changed, 58 insertions, 20 deletions

diff --git a/tools/testing/selftests/x86/iopl.c b/tools/testing/selftests/x86/iopl.c
index bab2f6e06b63..7e3e09c1abac 100644
--- a/tools/testing/selftests/x86/iopl.c
+++ b/tools/testing/selftests/x86/iopl.c
@@ -85,48 +85,88 @@ static void expect_gp_outb(unsigned short port)
 	printf("[OK]\toutb to 0x%02hx failed\n", port);
 }
 
-static bool try_cli(void)
+#define RET_FAULTED	0
+#define RET_FAIL	1
+#define RET_EMUL	2
+
+static int try_cli(void)
 {
+	unsigned long flags;
+
 	sethandler(SIGSEGV, sigsegv, SA_RESETHAND);
 	if (sigsetjmp(jmpbuf, 1) != 0) {
-		return false;
+		return RET_FAULTED;
 	} else {
-		asm volatile ("cli");
-		return true;
+		asm volatile("cli; pushf; pop %[flags]"
+				: [flags] "=rm" (flags));
+
+		/* X86_FLAGS_IF */
+		if (!(flags & (1 << 9)))
+			return RET_FAIL;
+		else
+			return RET_EMUL;
 	}
 	clearhandler(SIGSEGV);
 }
 
-static bool try_sti(void)
+static int try_sti(bool irqs_off)
 {
+	unsigned long flags;
+
 	sethandler(SIGSEGV, sigsegv, SA_RESETHAND);
 	if (sigsetjmp(jmpbuf, 1) != 0) {
-		return false;
+		return RET_FAULTED;
 	} else {
-		asm volatile ("sti");
-		return true;
+		asm volatile("sti; pushf; pop %[flags]"
+				: [flags] "=rm" (flags));
+
+		/* X86_FLAGS_IF */
+		if (irqs_off && (flags & (1 << 9)))
+			return RET_FAIL;
+		else
+			return RET_EMUL;
 	}
 	clearhandler(SIGSEGV);
 }
 
-static void expect_gp_sti(void)
+static void expect_gp_sti(bool irqs_off)
 {
-	if (try_sti()) {
+	int ret = try_sti(irqs_off);
+
+	switch (ret) {
+	case RET_FAULTED:
+		printf("[OK]\tSTI faulted\n");
+		break;
+	case RET_EMUL:
+		printf("[OK]\tSTI NOPped\n");
+		break;
+	default:
 		printf("[FAIL]\tSTI worked\n");
 		nerrs++;
-	} else {
-		printf("[OK]\tSTI faulted\n");
 	}
 }
 
-static void expect_gp_cli(void)
+/*
+ * Returns whether it managed to disable interrupts.
+ */
+static bool test_cli(void)
 {
-	if (try_cli()) {
+	int ret = try_cli();
+
+	switch (ret) {
+	case RET_FAULTED:
+		printf("[OK]\tCLI faulted\n");
+		break;
+	case RET_EMUL:
+		printf("[OK]\tCLI NOPped\n");
+		break;
+	default:
 		printf("[FAIL]\tCLI worked\n");
 		nerrs++;
-	} else {
-		printf("[OK]\tCLI faulted\n");
+		return true;
 	}
+
+	return false;
 }
 
 int main(void)
@@ -152,8 +192,7 @@ int main(void)
 	}
 
 	/* Make sure that CLI/STI are blocked even with IOPL level 3 */
-	expect_gp_cli();
-	expect_gp_sti();
+	expect_gp_sti(test_cli());
 	expect_ok_outb(0x80);
 
 	/* Establish an I/O bitmap to test the restore */
@@ -204,8 +243,7 @@ int main(void)
 	printf("[RUN]\tparent: write to 0x80 (should fail)\n");
 
 	expect_gp_outb(0x80);
-	expect_gp_cli();
-	expect_gp_sti();
+	expect_gp_sti(test_cli());
 
 	/* Test the capability checks. */
 	printf("\tiopl(3)\n");