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MIPS: Save static registers before sysmips

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commit 49955d84cd9ccdca5a16a495e448e1a06fad9e49 upstream.

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: f1e39a4a616c ("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
Patchwork: https://patchwork.linux-mips.org/patch/16149/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
James Hogan 2017-05-31 16:19:48 +01:00 committed by Greg Kroah-Hartman
parent a0ee412989
commit f87aa12039
5 changed files with 10 additions and 4 deletions
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2
arch/mips/kernel/scall32-o32.S
View File

@ -372,7 +372,7 @@ 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

@ -312,7 +312,7 @@ 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

@ -298,7 +298,7 @@ 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

@ -367,7 +367,7 @@ 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

@ -202,6 +202,12 @@ 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) {