Patch "MIPS: BPF: Fix build on pre-R2 little endian CPUs" has been added to the 4.2-stable tree

Patch "MIPS: BPF: Fix build on pre-R2 little endian CPUs" has been added to the 4.2-stable tree

[gregkh]

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

    MIPS: BPF: Fix build on pre-R2 little endian CPUs

to the 4.2-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-bpf-fix-build-on-pre-r2-little-endian-cpus.patch
and it can be found in the queue-4.2 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 b259e51f2e29390518021f9b8df55a3de42f371b Mon Sep 17 00:00:00 2001
From: Aurelien Jarno <aurelien@aurel32.net>
Date: Sat, 5 Sep 2015 18:46:57 +0200
Subject: MIPS: BPF: Fix build on pre-R2 little endian CPUs

From: Aurelien Jarno <aurelien@aurel32.net>

commit b259e51f2e29390518021f9b8df55a3de42f371b upstream.

The rotr, seh and wsbh instructions have been introduced with the R2
ISA. Thus the current BPF code fails to build on pre-R2 little endian
CPUs:

    CC      arch/mips/net/bpf_jit.o
    AS      arch/mips/net/bpf_jit_asm.o
  /home/aurel32/linux-4.2/arch/mips/net/bpf_jit_asm.S: Assembler messages:
  /home/aurel32/linux-4.2/arch/mips/net/bpf_jit_asm.S:67: Error: opcode not supported on this processor: mips32 (mips32) `wsbh $8,$19'
  /home/aurel32/linux-4.2/arch/mips/net/bpf_jit_asm.S:68: Error: opcode not supported on this processor: mips32 (mips32) `rotr $19,$8,16'
  /home/aurel32/linux-4.2/arch/mips/net/bpf_jit_asm.S:83: Error: opcode not supported on this processor: mips32 (mips32) `wsbh $8,$19'
  /home/aurel32/linux-4.2/arch/mips/net/bpf_jit_asm.S:84: Error: opcode not supported on this processor: mips32 (mips32) `seh $19,$8'
  /home/aurel32/linux-4.2/arch/mips/net/bpf_jit_asm.S:151: Error: opcode not supported on this processor: mips32 (mips32) `wsbh $8,$12'
  /home/aurel32/linux-4.2/arch/mips/net/bpf_jit_asm.S:153: Error: opcode not supported on this processor: mips32 (mips32) `rotr $19,$8,16'
  /home/aurel32/linux-4.2/arch/mips/net/bpf_jit_asm.S:164: Error: opcode not supported on this processor: mips32 (mips32) `wsbh $19,$12'
  /home/aurel32/linux-4.2/scripts/Makefile.build:294: recipe for target 'arch/mips/net/bpf_jit_asm.o' failed

Fix that by providing equivalent code for these CPUs.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11098/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/net/bpf_jit_asm.S |   42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

--- a/arch/mips/net/bpf_jit_asm.S
+++ b/arch/mips/net/bpf_jit_asm.S
@@ -64,8 +64,20 @@ sk_load_word_positive:
 	PTR_ADDU t1, $r_skb_data, offset
 	lw	$r_A, 0(t1)
 #ifdef CONFIG_CPU_LITTLE_ENDIAN
+# if defined(__mips_isa_rev) && (__mips_isa_rev >= 2)
 	wsbh	t0, $r_A
 	rotr	$r_A, t0, 16
+# else
+	sll	t0, $r_A, 24
+	srl	t1, $r_A, 24
+	srl	t2, $r_A, 8
+	or	t0, t0, t1
+	andi	t2, t2, 0xff00
+	andi	t1, $r_A, 0xff00
+	or	t0, t0, t2
+	sll	t1, t1, 8
+	or	$r_A, t0, t1
+# endif
 #endif
 	jr	$r_ra
 	 move	$r_ret, zero
@@ -80,8 +92,16 @@ sk_load_half_positive:
 	PTR_ADDU t1, $r_skb_data, offset
 	lh	$r_A, 0(t1)
 #ifdef CONFIG_CPU_LITTLE_ENDIAN
+# if defined(__mips_isa_rev) && (__mips_isa_rev >= 2)
 	wsbh	t0, $r_A
 	seh	$r_A, t0
+# else
+	sll	t0, $r_A, 24
+	andi	t1, $r_A, 0xff00
+	sra	t0, t0, 16
+	srl	t1, t1, 8
+	or	$r_A, t0, t1
+# endif
 #endif
 	jr	$r_ra
 	 move	$r_ret, zero
@@ -148,9 +168,22 @@ sk_load_byte_positive:
 NESTED(bpf_slow_path_word, (6 * SZREG), $r_sp)
 	bpf_slow_path_common(4)
 #ifdef CONFIG_CPU_LITTLE_ENDIAN
+# if defined(__mips_isa_rev) && (__mips_isa_rev >= 2)
 	wsbh	t0, $r_s0
 	jr	$r_ra
 	 rotr	$r_A, t0, 16
+# else
+	sll	t0, $r_s0, 24
+	srl	t1, $r_s0, 24
+	srl	t2, $r_s0, 8
+	or	t0, t0, t1
+	andi	t2, t2, 0xff00
+	andi	t1, $r_s0, 0xff00
+	or	t0, t0, t2
+	sll	t1, t1, 8
+	jr	$r_ra
+	 or	$r_A, t0, t1
+# endif
 #else
 	jr	$r_ra
 	 move	$r_A, $r_s0
@@ -161,8 +194,17 @@ NESTED(bpf_slow_path_word, (6 * SZREG),
 NESTED(bpf_slow_path_half, (6 * SZREG), $r_sp)
 	bpf_slow_path_common(2)
 #ifdef CONFIG_CPU_LITTLE_ENDIAN
+# if defined(__mips_isa_rev) && (__mips_isa_rev >= 2)
 	jr	$r_ra
 	 wsbh	$r_A, $r_s0
+# else
+	sll	t0, $r_s0, 8
+	andi	t1, $r_s0, 0xff00
+	andi	t0, t0, 0xff00
+	srl	t1, t1, 8
+	jr	$r_ra
+	 or	$r_A, t0, t1
+# endif
 #else
 	jr	$r_ra
 	 move	$r_A, $r_s0


Patches currently in stable-queue which might be from aurelien@aurel32.net are

queue-4.2/mips-bpf-fix-build-on-pre-r2-little-endian-cpus.patch
queue-4.2/mips-bpf-avoid-unreachable-code-on-little-endian.patch