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* [glibc] i386: Honor I386_USE_SYSENTER for 6-argument Linux system calls
@ 2022-05-04 14:54 Florian Weimer
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From: Florian Weimer @ 2022-05-04 14:54 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=60f0f2130d30cfd008ca39743027f1e200592dff
commit 60f0f2130d30cfd008ca39743027f1e200592dff
Author: Florian Weimer <fweimer@redhat.com>
Date: Wed May 4 15:37:21 2022 +0200
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:
---
sysdeps/unix/sysv/linux/i386/Makefile | 2 +-
.../unix/sysv/linux/i386/libc-do-syscall-int80.S | 25 ++++++++++++++++++++++
sysdeps/unix/sysv/linux/i386/sysdep.h | 13 +++++++++--
3 files changed, 37 insertions(+), 3 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/i386/Makefile b/sysdeps/unix/sysv/linux/i386/Makefile
index fcab129fc1..598e27dcda 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 0000000000..2c472f2557
--- /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 4558ab66cb..7085f7e19a 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")
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