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commit 2952c70804b48bb5c87eea21df5e401969dc4ec1
Author: Kevin Cernekee <cernekee@gmail.com>
Date: Tue Jun 5 15:05:20 2012 -0700
MIPS: Use $a0 instead of $v0 for __syscall_error() argument
$a0 is saved across _dl_runtime_resolve(); $v0 is not. Unfortunately,
__syscall_error() uses $v0 for its argument, not $a0 as is the MIPS ABI
standard. This means that if lazy binding was used for __syscall_error(),
the errno value in $v0 could get corrupted.
The problem can be easily seen in testcases where syscalls in librt fail;
when librt tries to call __syscall_error() in libc, the argument gets
lost and errno gets set to a bogus value:
# ./tst-mqueue1 ; echo $?
mq_receive on O_WRONLY mqd_t did not fail with EBADF: Unknown error 2004684208
1
# ./tst-mqueue2 ; echo $?
mq_timedreceive with too small msg_len did not fail with EMSGSIZE: Unknown error 1997360560
1
# ./tst-mqueue4 ; echo $?
mq_timedsend did not fail with ETIMEDOUT: Unknown error 2008747440
1
When _dl_runtime_resolve() was taken out of the equation, the same test
cases passed:
# LD_BIND_NOW=y ./tst-mqueue1 ; echo $?
0
# LD_BIND_NOW=y ./tst-mqueue2 ; echo $?
0
# LD_BIND_NOW=y ./tst-mqueue4 ; echo $?
0
Changing __syscall_error() to look at $a0 instead of $v0 fixed the
problem.
(Note that there is also a "__syscall_error.c" file which presumably
uses the standard C calling conventions, but I do not think it is used
on MIPS.)
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
commit 3c58d95d918c7e2fda374c37a52f81b34b81e4ca
Author: Kevin Cernekee <cernekee@gmail.com>
Date: Tue Jun 5 15:05:19 2012 -0700
MIPS: Convert __syscall_error() callers to use $a0 for argument
Some callers passed the first argument in $v0, while others used $a0.
Change the callers to use $a0 consistently.
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
--- a/libc/sysdeps/linux/mips/vfork.S
+++ b/libc/sysdeps/linux/mips/vfork.S
@@ -84,6 +84,7 @@ NESTED(__vfork,FRAMESZ,sp)
/* Something bad happened -- no child created. */
L(error):
+ move a0, v0
#ifdef __PIC__
PTR_LA t9, __syscall_error
RESTORE_GP64
--- a/libpthread/linuxthreads/sysdeps/unix/sysv/linux/mips/mips64/sysdep-cancel.h
+++ b/libpthread/linuxthreads/sysdeps/unix/sysv/linux/mips/mips64/sysdep-cancel.h
@@ -31,7 +31,7 @@
# undef PSEUDO
# define PSEUDO(name, syscall_name, args) \
.align 2; \
- 99: \
+ 99: move a0, v0; \
PTR_LA t9,__syscall_error; \
/* manual cpreturn. */ \
REG_L gp, STKOFF_GP(sp); \
--- a/libpthread/linuxthreads/sysdeps/unix/sysv/linux/mips/vfork.S
+++ b/libpthread/linuxthreads/sysdeps/unix/sysv/linux/mips/vfork.S
@@ -80,6 +80,7 @@ NESTED(__vfork,FRAMESZ,sp)
/* Something bad happened -- no child created. */
L(error):
+ move a0, v0
#ifdef __PIC__
PTR_LA t9, __syscall_error
RESTORE_GP64
--- a/libc/sysdeps/linux/mips/syscall_error.S
+++ b/libc/sysdeps/linux/mips/syscall_error.S
@@ -43,7 +43,7 @@ ENTRY(__syscall_error)
#ifdef __PIC__
SAVE_GP(GPOFF)
#endif
- REG_S v0, V0OFF(sp)
+ REG_S a0, V0OFF(sp)
REG_S ra, RAOFF(sp)
/* Find our per-thread errno address */
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