This is a note to let you know that I've just added the patch titled MIPS: Save static registers before sysmips to the 3.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mips-save-static-registers-before-sysmips.patch and it can be found in the queue-3.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 49955d84cd9ccdca5a16a495e448e1a06fad9e49 Mon Sep 17 00:00:00 2001 From: James Hogan <james.hogan@xxxxxxxxxx> Date: Wed, 31 May 2017 16:19:48 +0100 Subject: MIPS: Save static registers before sysmips From: James Hogan <james.hogan@xxxxxxxxxx> 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@xxxxxxxxxx> Cc: linux-mips@xxxxxxxxxxxxxx Patchwork: https://patchwork.linux-mips.org/patch/16149/ Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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(-) --- a/arch/mips/kernel/scall32-o32.S +++ b/arch/mips/kernel/scall32-o32.S @@ -361,7 +361,7 @@ 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 --- a/arch/mips/kernel/scall64-64.S +++ b/arch/mips/kernel/scall64-64.S @@ -318,7 +318,7 @@ 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 --- a/arch/mips/kernel/scall64-n32.S +++ b/arch/mips/kernel/scall64-n32.S @@ -307,7 +307,7 @@ 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 --- a/arch/mips/kernel/scall64-o32.S +++ b/arch/mips/kernel/scall64-o32.S @@ -358,7 +358,7 @@ 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 --- a/arch/mips/kernel/syscall.c +++ b/arch/mips/kernel/syscall.c @@ -200,6 +200,12 @@ static inline int mips_atomic_set(unsign 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) { Patches currently in stable-queue which might be from james.hogan@xxxxxxxxxx are queue-3.18/mips-actually-decode-jalx-in-__compute_return_epc_for_insn.patch queue-3.18/mips-fix-mips_atomic_set-retry-condition.patch queue-3.18/mips-fix-mips_atomic_set-with-eva.patch queue-3.18/mips-save-static-registers-before-sysmips.patch queue-3.18/mips-fix-unaligned-pc-interpretation-in-compute_return_epc.patch queue-3.18/mips-negate-error-syscall-return-in-trace.patch queue-3.18/mips-math-emu-prevent-wrong-isa-mode-instruction-emulation.patch