This is a note to let you know that I've just added the patch titled
selftests/x86/amx: Add a ptrace test
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
selftests-x86-amx-add-a-ptrace-test.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 62faca1ca10cc84e99ae7f38aa28df2bc945369b Mon Sep 17 00:00:00 2001
From: "Chang S. Bae" <chang.seok.bae@xxxxxxxxx>
Date: Mon, 27 Feb 2023 13:05:04 -0800
Subject: selftests/x86/amx: Add a ptrace test
From: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
commit 62faca1ca10cc84e99ae7f38aa28df2bc945369b upstream.
Include a test case to validate the XTILEDATA injection to the target.
Also, it ensures the kernel's ability to copy states between different
XSAVE formats.
Refactor the memcmp() code to be usable for the state validation.
Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/all/20230227210504.18520-3-chang.seok.bae%40intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/x86/amx.c | 108 ++++++++++++++++++++++++++++++++++++--
1 file changed, 105 insertions(+), 3 deletions(-)
--- 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_r
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();
Patches currently in stable-queue which might be from chang.seok.bae@xxxxxxxxx are
queue-6.2/selftests-x86-amx-add-a-ptrace-test.patch
queue-6.2/x86-fpu-xstate-prevent-false-positive-warning-in-__copy_xstate_uabi_buf.patch
