[PATCH] x32/cet: Enable shadow stack during startup for Linux 6.10-rc4

[PATCH] x32/cet: Enable shadow stack during startup for Linux 6.10-rc4

[H.J. Lu]

Enable shadow stack during startup for Linux 6.10-rc4:

commit 2883f01ec37dd8668e7222dfdb5980c86fdfe277
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Fri Mar 15 07:04:33 2024 -0700

    x86/shstk: Enable shadow stacks for x32

    1. Add shadow stack support to x32 signal.
    2. Use the 64-bit map_shadow_stack syscall for x32.
    3. Set up shadow stack for x32.

Add the map_shadow_stack system call to <fixup-asm-unistd.h> and regenerate
arch-syscall.h.  Tested on Intel Tiger Lake.
---
 sysdeps/unix/sysv/linux/x86_64/x32/arch-syscall.h     | 1 +
 sysdeps/unix/sysv/linux/x86_64/x32/fixup-asm-unistd.h | 4 ++++
 sysdeps/x86_64/x32/dl-machine.h                       | 7 +++++--
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/arch-syscall.h b/sysdeps/unix/sysv/linux/x86_64/x32/arch-syscall.h
index 3040a47d72..df3e22236d 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/arch-syscall.h
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/arch-syscall.h
@@ -155,6 +155,7 @@
 #define __NR_lsm_set_self_attr 1073742284
 #define __NR_lstat 1073741830
 #define __NR_madvise 1073741852
+#define __NR_map_shadow_stack 1073742277
 #define __NR_mbind 1073742061
 #define __NR_membarrier 1073742148
 #define __NR_memfd_create 1073742143
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/fixup-asm-unistd.h b/sysdeps/unix/sysv/linux/x86_64/x32/fixup-asm-unistd.h
index 98124169e6..47fa8af4ce 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/fixup-asm-unistd.h
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/fixup-asm-unistd.h
@@ -15,6 +15,10 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#ifndef __NR_map_shadow_stack
+# define __NR_map_shadow_stack 1073742277
+#endif
+
 /* X32 uses the same 64-bit syscall interface for set_thread_area.   */
 #ifndef __NR_set_thread_area
 # define __NR_set_thread_area 1073742029
diff --git a/sysdeps/x86_64/x32/dl-machine.h b/sysdeps/x86_64/x32/dl-machine.h
index c35cee9261..3eb59bde7c 100644
--- a/sysdeps/x86_64/x32/dl-machine.h
+++ b/sysdeps/x86_64/x32/dl-machine.h
@@ -45,13 +45,16 @@ _start:\n\
 _dl_start_user:\n\
 	# Save the user entry point address in %r12.\n\
 	movl %eax, %r12d\n\
+	# Save %rsp value in %r13.\n\
+	movl %esp, %r13d\n\
+"\
+	RTLD_START_ENABLE_X86_FEATURES \
+"\
 	# Read the original argument count.\n\
 	movl (%rsp), %edx\n\
 	# Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
 	# argc -> rsi\n\
 	movl %edx, %esi\n\
-	# Save %rsp value in %r13.\n\
-	movl %esp, %r13d\n\
 	# And align stack for the _dl_init call.\n\
 	and $-16, %esp\n\
 	# _dl_loaded -> rdi\n\
-- 
2.45.2