Patch "MIPS: Avoid BUG warning in arch_check_elf" has been added to the 4.9-stable tree

Patch "MIPS: Avoid BUG warning in arch_check_elf" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    MIPS: Avoid BUG warning in arch_check_elf

to the 4.9-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-avoid-bug-warning-in-arch_check_elf.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From c46f59e90226fa5bfcc83650edebe84ae47d454b Mon Sep 17 00:00:00 2001
From: James Cowgill <James.Cowgill@imgtec.com>
Date: Tue, 11 Apr 2017 13:51:07 +0100
Subject: MIPS: Avoid BUG warning in arch_check_elf

From: James Cowgill <James.Cowgill@imgtec.com>

commit c46f59e90226fa5bfcc83650edebe84ae47d454b upstream.

arch_check_elf contains a usage of current_cpu_data that will call
smp_processor_id() with preemption enabled and therefore triggers a
"BUG: using smp_processor_id() in preemptible" warning when an fpxx
executable is loaded.

As a follow-up to commit b244614a60ab ("MIPS: Avoid a BUG warning during
prctl(PR_SET_FP_MODE, ...)"), apply the same fix to arch_check_elf by
using raw_current_cpu_data instead. The rationale quoted from the previous
commit:

"It is assumed throughout the kernel that if any CPU has an FPU, then
all CPUs would have an FPU as well, so it is safe to perform the check
with preemption enabled - change the code to use raw_ variant of the
check to avoid the warning."

Fixes: 46490b572544 ("MIPS: kernel: elf: Improve the overall ABI and FPU mode checks")
Signed-off-by: James Cowgill <James.Cowgill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15951/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/kernel/elf.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/mips/kernel/elf.c
+++ b/arch/mips/kernel/elf.c
@@ -257,7 +257,7 @@ int arch_check_elf(void *_ehdr, bool has
 	else if ((prog_req.fr1 && prog_req.frdefault) ||
 		 (prog_req.single && !prog_req.frdefault))
 		/* Make sure 64-bit MIPS III/IV/64R1 will not pick FR1 */
-		state->overall_fp_mode = ((current_cpu_data.fpu_id & MIPS_FPIR_F64) &&
+		state->overall_fp_mode = ((raw_current_cpu_data.fpu_id & MIPS_FPIR_F64) &&
 					  cpu_has_mips_r2_r6) ?
 					  FP_FR1 : FP_FR0;
 	else if (prog_req.fr1)


Patches currently in stable-queue which might be from James.Cowgill@imgtec.com are

queue-4.9/mips-avoid-bug-warning-in-arch_check_elf.patch