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[PATCH] [BZ #19371] Properly handle x32 syscall
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>
- Date: Wed, 16 Dec 2015 07:01:39 -0800
- Subject: [PATCH] [BZ #19371] Properly handle x32 syscall
- Authentication-results: sourceware.org; auth=none
X32 syscall() may return 64-bit integer as lseek, time and times. Its
return type should be __syscall_slong_t instead of long int. We need
to properly return 64-bit error value.
Before the patch:
Dump of assembler code for function syscall:
0x000dab20 <+0>: mov %rdi,%rax
0x000dab23 <+3>: mov %rsi,%rdi
0x000dab26 <+6>: mov %rdx,%rsi
0x000dab29 <+9>: mov %rcx,%rdx
0x000dab2c <+12>: mov %r8,%r10
0x000dab2f <+15>: mov %r9,%r8
0x000dab32 <+18>: mov 0x8(%rsp),%r9
0x000dab37 <+23>: syscall
0x000dab39 <+25>: cmp $0xfffffffffffff001,%rax
0x000dab3f <+31>: jae 0xdab42 <syscall+34>
0x000dab41 <+33>: retq
0x000dab42 <+34>: mov 0x2b3367(%rip),%rcx # 0x38deb0
0x000dab49 <+41>: neg %eax
0x000dab4b <+43>: mov %eax,%fs:(%rcx)
0x000dab4e <+46>: or $0xffffffff,%eax
^^^^^^^^^^^^^^^^^^ This is 32-bit error return.
0x000dab51 <+49>: retq
End of assembler dump.
After the patch:
Dump of assembler code for function syscall:
0x000daaf0 <+0>: mov %rdi,%rax
0x000daaf3 <+3>: mov %rsi,%rdi
0x000daaf6 <+6>: mov %rdx,%rsi
0x000daaf9 <+9>: mov %rcx,%rdx
0x000daafc <+12>: mov %r8,%r10
0x000daaff <+15>: mov %r9,%r8
0x000dab02 <+18>: mov 0x8(%rsp),%r9
0x000dab07 <+23>: syscall
0x000dab09 <+25>: cmp $0xfffffffffffff001,%rax
0x000dab0f <+31>: jae 0xdab12 <syscall+34>
0x000dab11 <+33>: retq
0x000dab12 <+34>: mov 0x2b3397(%rip),%rcx # 0x38deb0
0x000dab19 <+41>: neg %eax
0x000dab1b <+43>: mov %eax,%fs:(%rcx)
0x000dab1e <+46>: or $0xffffffffffffffff,%rax
0x000dab22 <+50>: retq
End of assembler dump.
OK for master?
H.J.
---
[BZ #19371]
* posix/unistd.h (syscall): Use __syscall_slong_t for return
type.
* sysdeps/unix/sysv/linux/x86_64/x32/syscall.S: New file.
---
posix/unistd.h | 2 +-
sysdeps/unix/sysv/linux/x86_64/x32/syscall.S | 33 ++++++++++++++++++++++++++++
2 files changed, 34 insertions(+), 1 deletion(-)
create mode 100644 sysdeps/unix/sysv/linux/x86_64/x32/syscall.S
diff --git a/posix/unistd.h b/posix/unistd.h
index 1b52930..bb61ad7 100644
--- a/posix/unistd.h
+++ b/posix/unistd.h
@@ -1058,7 +1058,7 @@ extern void *sbrk (intptr_t __delta) __THROW;
In Mach, all system calls take normal arguments and always return an
error code (zero for success). */
-extern long int syscall (long int __sysno, ...) __THROW;
+extern __syscall_slong_t syscall (long int __sysno, ...) __THROW;
#endif /* Use misc. */
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/syscall.S b/sysdeps/unix/sysv/linux/x86_64/x32/syscall.S
new file mode 100644
index 0000000..cc5255f
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/syscall.S
@@ -0,0 +1,33 @@
+/* The syscall system call. Linux/x32 version.
+ Copyright (C) 2015 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
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+
+/* Return -1LL in a full 64 bits. */
+#undef SYSCALL_ERROR_HANDLER
+#define SYSCALL_ERROR_HANDLER \
+0: \
+ SYSCALL_SET_ERRNO; \
+ orq $-1, %rax; \
+ ret;
+
+/* Always use our own error handler. */
+#undef SYSCALL_ERROR_LABEL
+#define SYSCALL_ERROR_LABEL 0f
+
+#include <sysdeps/unix/sysv/linux/x86_64/syscall.S>
--
2.5.0