Patch "MIPS: Save static registers before sysmips" has been added to the 3.18-stable tree

PATCH [email protected] 1 participant 1 message Jul 25, 2017

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2017-07-25 04:32 UTC #0 lore raw

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 <[email protected]> know about it.

Quoted 1 line

From 49955d84cd9ccdca5a16a495e448e1a06fad9e49 Mon Sep 17 00:00:00 2001

From: James Hogan <[email protected]>
Date: Wed, 31 May 2017 16:19:48 +0100
Subject: MIPS: Save static registers before sysmips

From: James Hogan <[email protected]>

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 <[email protected]>

Cc [email protected]

Patchwork: https://patchwork.linux-mips.org/patch/16149/

Signed-off-by Ralf Baechle <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 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(-)

arch/mips/kernel/scall32-o32.S +1 -1

@@ -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

arch/mips/kernel/scall64-64.S +1 -1

@@ -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

arch/mips/kernel/scall64-n32.S +1 -1

@@ -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

arch/mips/kernel/scall64-o32.S +1 -1

@@ -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

arch/mips/kernel/syscall.c +6 -0

@@ -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 [email protected] 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