Patch "ARM: net: bpf: fix stack alignment" has been added to the 4.14-stable tree

Patch "ARM: net: bpf: fix stack alignment" has been added to the 4.14-stable tree

[gregkh]

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

    ARM: net: bpf: fix stack alignment

to the 4.14-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:
     arm-net-bpf-fix-stack-alignment.patch
and it can be found in the queue-4.14 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 d1220efd23484c72c82d5471f05daeb35b5d1916 Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@armlinux.org.uk>
Date: Sat, 13 Jan 2018 16:10:07 +0000
Subject: ARM: net: bpf: fix stack alignment

From: Russell King <rmk+kernel@armlinux.org.uk>

commit d1220efd23484c72c82d5471f05daeb35b5d1916 upstream.

As per 2dede2d8e925 ("ARM EABI: stack pointer must be 64-bit aligned
after a CPU exception") the stack should be aligned to a 64-bit boundary
on EABI systems.  Ensure that the eBPF JIT appropraitely aligns the
stack.

Fixes: 39c13c204bb1 ("arm: eBPF JIT compiler")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm/net/bpf_jit_32.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -179,8 +179,13 @@ static void jit_fill_hole(void *area, un
 		*ptr++ = __opcode_to_mem_arm(ARM_INST_UDF);
 }
 
-/* Stack must be multiples of 16 Bytes */
-#define STACK_ALIGN(sz) (((sz) + 3) & ~3)
+#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5)
+/* EABI requires the stack to be aligned to 64-bit boundaries */
+#define STACK_ALIGNMENT	8
+#else
+/* Stack must be aligned to 32-bit boundaries */
+#define STACK_ALIGNMENT	4
+#endif
 
 /* Stack space for BPF_REG_2, BPF_REG_3, BPF_REG_4,
  * BPF_REG_5, BPF_REG_7, BPF_REG_8, BPF_REG_9,
@@ -194,7 +199,7 @@ static void jit_fill_hole(void *area, un
 	 + SCRATCH_SIZE + \
 	 + 4 /* extra for skb_copy_bits buffer */)
 
-#define STACK_SIZE STACK_ALIGN(_STACK_SIZE)
+#define STACK_SIZE ALIGN(_STACK_SIZE, STACK_ALIGNMENT)
 
 /* Get the offset of eBPF REGISTERs stored on scratch space. */
 #define STACK_VAR(off) (STACK_SIZE-off-4)


Patches currently in stable-queue which might be from rmk+kernel@armlinux.org.uk are

queue-4.14/arm-net-bpf-fix-stack-alignment.patch
queue-4.14/arm-net-bpf-fix-ldx-instructions.patch
queue-4.14/arm-net-bpf-fix-register-saving.patch
queue-4.14/arm-net-bpf-move-stack-documentation.patch
queue-4.14/arm-net-bpf-correct-stack-layout-documentation.patch
queue-4.14/arm-net-bpf-clarify-tail_call-index.patch
queue-4.14/arm-net-bpf-avoid-bx-instruction-on-non-thumb-capable-cpus.patch
queue-4.14/arm-net-bpf-fix-tail-call-jumps.patch