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MIPS: Save static registers before sysmips 

The MIPS sysmips system call handler may return directly from the
MIPS_ATOMIC_SET case (mips_atomic_set()) to syscall_exit. This path
restores the static (callee saved) registers, however they won't have
been saved on entry to the system call.

Use the save_static_function() macro to create a __sys_sysmips wrapper
function which saves the static registers before calling sys_sysmips, so
that the correct static register state is restored by syscall_exit.

Fixes: f1e39a4a61 ("MIPS: Rewrite sysmips(MIPS_ATOMIC_SET, ...) in C with inline assembler")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/16149/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
James Hogan 2017-05-31 16:19:48 +01:00 committed by Ralf Baechle
parent 2ec420b26f
commit 49955d84cd
5 changed files with 10 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/mips/kernel/scall32-o32.S
View File

@ -371,7 +371,7 @@ EXPORT(sys_call_table)
PTR sys_writev
PTR sys_cacheflush
PTR sys_cachectl
PTR sys_sysmips
PTR __sys_sysmips
PTR sys_ni_syscall /* 4150 */
PTR sys_getsid
PTR sys_fdatasync

2
arch/mips/kernel/scall64-64.S
View File

@ -311,7 +311,7 @@ EXPORT(sys_call_table)
PTR sys_sched_getaffinity
PTR sys_cacheflush
PTR sys_cachectl
PTR sys_sysmips
PTR __sys_sysmips
PTR sys_io_setup /* 5200 */
PTR sys_io_destroy
PTR sys_io_getevents

2
arch/mips/kernel/scall64-n32.S
View File

@ -302,7 +302,7 @@ EXPORT(sysn32_call_table)
PTR compat_sys_sched_getaffinity
PTR sys_cacheflush
PTR sys_cachectl
PTR sys_sysmips
PTR __sys_sysmips
PTR compat_sys_io_setup /* 6200 */
PTR sys_io_destroy
PTR compat_sys_io_getevents

2
arch/mips/kernel/scall64-o32.S
View File

@ -371,7 +371,7 @@ EXPORT(sys32_call_table)
PTR compat_sys_writev
PTR sys_cacheflush
PTR sys_cachectl
PTR sys_sysmips
PTR __sys_sysmips
PTR sys_ni_syscall /* 4150 */
PTR sys_getsid
PTR sys_fdatasync

6
arch/mips/kernel/syscall.c
View File

@ -192,6 +192,12 @@ static inline int mips_atomic_set(unsigned long addr, unsigned long new)
unreachable();
}
/*
* mips_atomic_set() normally returns directly via syscall_exit potentially
* clobbering static registers, so be sure to preserve them.
*/
save_static_function(sys_sysmips);
SYSCALL_DEFINE3(sysmips, long, cmd, long, arg1, long, arg2)
{
switch (cmd) {