Merge tag 'x86_urgent_for_v6.3_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Borislav Petkov:

 - Add a AMX ptrace self test

 - Prevent a false-positive warning when retrieving the (invalid)
   address of dynamic FPU features in their init state which are not
   saved in init_fpstate at all

 - Randomize per-CPU entry areas only when KASLR is enabled

* tag 'x86_urgent_for_v6.3_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  selftests/x86/amx: Add a ptrace test
  x86/fpu/xstate: Prevent false-positive warning in __copy_xstate_uabi_buf()
  x86/mm: Do not shuffle CPU entry areas without KASLR

1 files changed, 105 insertions, 3 deletions

diff --git a/tools/testing/selftests/x86/amx.c b/tools/testing/selftests/x86/amx.c
index 625e42901237..d884fd69dd51 100644
--- a/tools/testing/selftests/x86/amx.c
+++ b/tools/testing/selftests/x86/amx.c
@@ -14,8 +14,10 @@
 #include <sys/auxv.h>
 #include <sys/mman.h>
 #include <sys/shm.h>
+#include <sys/ptrace.h>
 #include <sys/syscall.h>
 #include <sys/wait.h>
+#include <sys/uio.h>
 
 #include "../kselftest.h" /* For __cpuid_count() */
 
@@ -583,6 +585,13 @@ static void test_dynamic_state(void)
 	_exit(0);
 }
 
+static inline int __compare_tiledata_state(struct xsave_buffer *xbuf1, struct xsave_buffer *xbuf2)
+{
+	return memcmp(&xbuf1->bytes[xtiledata.xbuf_offset],
+		      &xbuf2->bytes[xtiledata.xbuf_offset],
+		      xtiledata.size);
+}
+
 /*
  * Save current register state and compare it to @xbuf1.'
  *
@@ -599,9 +608,7 @@ static inline bool __validate_tiledata_regs(struct xsave_buffer *xbuf1)
 		fatal_error("failed to allocate XSAVE buffer\n");
 
 	xsave(xbuf2, XFEATURE_MASK_XTILEDATA);
-	ret = memcmp(&xbuf1->bytes[xtiledata.xbuf_offset],
-		     &xbuf2->bytes[xtiledata.xbuf_offset],
-		     xtiledata.size);
+	ret = __compare_tiledata_state(xbuf1, xbuf2);
 
 	free(xbuf2);
 
@@ -826,6 +833,99 @@ static void test_context_switch(void)
 	free(finfo);
 }
 
+/* Ptrace test */
+
+/*
+ * Make sure the ptracee has the expanded kernel buffer on the first
+ * use. Then, initialize the state before performing the state
+ * injection from the ptracer.
+ */
+static inline void ptracee_firstuse_tiledata(void)
+{
+	load_rand_tiledata(stashed_xsave);
+	init_xtiledata();
+}
+
+/*
+ * Ptracer injects the randomized tile data state. It also reads
+ * before and after that, which will execute the kernel's state copy
+ * functions. So, the tester is advised to double-check any emitted
+ * kernel messages.
+ */
+static void ptracer_inject_tiledata(pid_t target)
+{
+	struct xsave_buffer *xbuf;
+	struct iovec iov;
+
+	xbuf = alloc_xbuf();
+	if (!xbuf)
+		fatal_error("unable to allocate XSAVE buffer");
+
+	printf("\tRead the init'ed tiledata via ptrace().\n");
+
+	iov.iov_base = xbuf;
+	iov.iov_len = xbuf_size;
+
+	memset(stashed_xsave, 0, xbuf_size);
+
+	if (ptrace(PTRACE_GETREGSET, target, (uint32_t)NT_X86_XSTATE, &iov))
+		fatal_error("PTRACE_GETREGSET");
+
+	if (!__compare_tiledata_state(stashed_xsave, xbuf))
+		printf("[OK]\tThe init'ed tiledata was read from ptracee.\n");
+	else
+		printf("[FAIL]\tThe init'ed tiledata was not read from ptracee.\n");
+
+	printf("\tInject tiledata via ptrace().\n");
+
+	load_rand_tiledata(xbuf);
+
+	memcpy(&stashed_xsave->bytes[xtiledata.xbuf_offset],
+	       &xbuf->bytes[xtiledata.xbuf_offset],
+	       xtiledata.size);
+
+	if (ptrace(PTRACE_SETREGSET, target, (uint32_t)NT_X86_XSTATE, &iov))
+		fatal_error("PTRACE_SETREGSET");
+
+	if (ptrace(PTRACE_GETREGSET, target, (uint32_t)NT_X86_XSTATE, &iov))
+		fatal_error("PTRACE_GETREGSET");
+
+	if (!__compare_tiledata_state(stashed_xsave, xbuf))
+		printf("[OK]\tTiledata was correctly written to ptracee.\n");
+	else
+		printf("[FAIL]\tTiledata was not correctly written to ptracee.\n");
+}
+
+static void test_ptrace(void)
+{
+	pid_t child;
+	int status;
+
+	child = fork();
+	if (child < 0) {
+		err(1, "fork");
+	} else if (!child) {
+		if (ptrace(PTRACE_TRACEME, 0, NULL, NULL))
+			err(1, "PTRACE_TRACEME");
+
+		ptracee_firstuse_tiledata();
+
+		raise(SIGTRAP);
+		_exit(0);
+	}
+
+	do {
+		wait(&status);
+	} while (WSTOPSIG(status) != SIGTRAP);
+
+	ptracer_inject_tiledata(child);
+
+	ptrace(PTRACE_DETACH, child, NULL, NULL);
+	wait(&status);
+	if (!WIFEXITED(status) || WEXITSTATUS(status))
+		err(1, "ptrace test");
+}
+
 int main(void)
 {
 	/* Check hardware availability at first */
@@ -846,6 +946,8 @@ int main(void)
 	ctxtswtest_config.num_threads = 5;
 	test_context_switch();
 
+	test_ptrace();
+
 	clearhandler(SIGILL);
 	free_stashed_xsave();