From: Florian Weimer <fweimer@redhat.com>
Date: Wed, 4 May 2022 13:37:21 +0000 (+0200)
Subject: i386: Honor I386_USE_SYSENTER for 6-argument Linux system calls
X-Git-Tag: glibc-2.36~314
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=60f0f2130d30cfd008ca39743027f1e200592dff;p=thirdparty%2Fglibc.git

i386: Honor I386_USE_SYSENTER for 6-argument Linux system calls

Introduce an int-80h-based version of __libc_do_syscall and use
it if I386_USE_SYSENTER is defined as 0.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
---

diff --git a/sysdeps/unix/sysv/linux/i386/Makefile b/sysdeps/unix/sysv/linux/i386/Makefile
index fcab129fc1d..598e27dcdae 100644
--- a/sysdeps/unix/sysv/linux/i386/Makefile
+++ b/sysdeps/unix/sysv/linux/i386/Makefile
@@ -13,7 +13,7 @@ install-bin += lddlibc4
 endif
 
 ifeq ($(subdir),io)
-sysdep_routines += libc-do-syscall
+sysdep_routines += libc-do-syscall libc-do-syscall-int80
 endif
 
 ifeq ($(subdir),stdlib)
diff --git a/sysdeps/unix/sysv/linux/i386/libc-do-syscall-int80.S b/sysdeps/unix/sysv/linux/i386/libc-do-syscall-int80.S
new file mode 100644
index 00000000000..2c472f25573
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/i386/libc-do-syscall-int80.S
@@ -0,0 +1,25 @@
+/* Out-of-line syscall stub for six-argument syscalls from C.  For static PIE.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef SHARED
+# define I386_USE_SYSENTER 0
+# include <sysdep.h>
+
+# define __libc_do_syscall __libc_do_syscall_int80
+# include "libc-do-syscall.S"
+#endif
diff --git a/sysdeps/unix/sysv/linux/i386/sysdep.h b/sysdeps/unix/sysv/linux/i386/sysdep.h
index 4558ab66cb6..7085f7e19ac 100644
--- a/sysdeps/unix/sysv/linux/i386/sysdep.h
+++ b/sysdeps/unix/sysv/linux/i386/sysdep.h
@@ -42,6 +42,15 @@
 # endif
 #endif
 
+#if !I386_USE_SYSENTER && IS_IN (libc) && !defined SHARED
+/* Inside static libc, we have two versions.  For compilation units
+   with !I386_USE_SYSENTER, the vDSO entry mechanism cannot be
+   used. */
+# define I386_DO_SYSCALL_STRING "__libc_do_syscall_int80"
+#else
+# define I386_DO_SYSCALL_STRING "__libc_do_syscall"
+#endif
+
 #ifdef __ASSEMBLER__
 
 /* Linux uses a negative return value to indicate syscall errors,
@@ -301,7 +310,7 @@ struct libc_do_syscall_args
     };									\
     asm volatile (							\
     "movl %1, %%eax\n\t"						\
-    "call __libc_do_syscall"						\
+    "call " I386_DO_SYSCALL_STRING					\
     : "=a" (resultvar)							\
     : "i" (__NR_##name), "c" (arg2), "d" (arg3), "S" (arg4), "D" (&_xv) \
     : "memory", "cc")
@@ -315,7 +324,7 @@ struct libc_do_syscall_args
     };									\
     asm volatile (							\
     "movl %1, %%eax\n\t"						\
-    "call __libc_do_syscall"						\
+    "call " I386_DO_SYSCALL_STRING					\
     : "=a" (resultvar)							\
     : "a" (name), "c" (arg2), "d" (arg3), "S" (arg4), "D" (&_xv)	\
     : "memory", "cc")