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@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
---
arch/mips/kernel/scall32-o32.S | 2 +-
arch/mips/kernel/scall64-64.S | 2 +-
arch/mips/kernel/scall64-n32.S | 2 +-
arch/mips/kernel/scall64-o32.S | 2 +-
arch/mips/kernel/syscall.c | 6 ++++++
5 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/arch/mips/kernel/scall32-o32.S b/arch/mips/kernel/scall32-o32.S
index 80ed68b2c95e..27c2f90eeb21 100644
--- a/arch/mips/kernel/scall32-o32.S
+++ b/arch/mips/kernel/scall32-o32.S
@@ -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
diff --git a/arch/mips/kernel/scall64-64.S b/arch/mips/kernel/scall64-64.S
index 49765b44aa9b..65d5aeeb9bdb 100644
--- a/arch/mips/kernel/scall64-64.S
+++ b/arch/mips/kernel/scall64-64.S
@@ -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
diff --git a/arch/mips/kernel/scall64-n32.S b/arch/mips/kernel/scall64-n32.S
index 90bad2d1b2d3..cbf190ef9e8a 100644
--- a/arch/mips/kernel/scall64-n32.S
+++ b/arch/mips/kernel/scall64-n32.S
@@ -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
diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
index 2dd70bd104e1..c30bc520885f 100644
--- a/arch/mips/kernel/scall64-o32.S
+++ b/arch/mips/kernel/scall64-o32.S
@@ -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
diff --git a/arch/mips/kernel/syscall.c b/arch/mips/kernel/syscall.c
index 9dd0788fc56d..3971220ea925 100644
--- a/arch/mips/kernel/syscall.c
+++ b/arch/mips/kernel/syscall.c
@@ -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) {
--
git-series 0.8.10