This is a note to let you know that I've just added the patch titled
x86: bpf_jit: fix FROM_BE16 and FROM_LE16/32 instructions
to the 4.0-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:
x86-bpf_jit-fix-from_be16-and-from_le16-32-instructions.patch
and it can be found in the queue-4.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From foo@baz Sat Jun 13 09:48:35 PDT 2015
From: Alexei Starovoitov <[email protected]>
Date: Mon, 11 May 2015 23:25:16 -0700
Subject: x86: bpf_jit: fix FROM_BE16 and FROM_LE16/32 instructions
From: Alexei Starovoitov <[email protected]>
[ Upstream commit 343f845b375989f1753f605902931fa939aa2223 ]
FROM_BE16:
'ror %reg, 8' doesn't clear upper bits of the register,
so use additional 'movzwl' insn to zero extend 16 bits into 64
FROM_LE16:
should zero extend lower 16 bits into 64 bit
FROM_LE32:
should zero extend lower 32 bits into 64 bit
Fixes: 89aa075832b0 ("net: sock: allow eBPF programs to be attached to sockets")
Signed-off-by: Alexei Starovoitov <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/x86/net/bpf_jit_comp.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -559,6 +559,13 @@ static int do_jit(struct bpf_prog *bpf_p
if (is_ereg(dst_reg))
EMIT1(0x41);
EMIT3(0xC1, add_1reg(0xC8, dst_reg), 8);
+
+ /* emit 'movzwl eax, ax' */
+ if (is_ereg(dst_reg))
+ EMIT3(0x45, 0x0F, 0xB7);
+ else
+ EMIT2(0x0F, 0xB7);
+ EMIT1(add_2reg(0xC0, dst_reg, dst_reg));
break;
case 32:
/* emit 'bswap eax' to swap lower 4 bytes */
@@ -577,6 +584,27 @@ static int do_jit(struct bpf_prog *bpf_p
break;
case BPF_ALU | BPF_END | BPF_FROM_LE:
+ switch (imm32) {
+ case 16:
+ /* emit 'movzwl eax, ax' to zero extend 16-bit
+ * into 64 bit
+ */
+ if (is_ereg(dst_reg))
+ EMIT3(0x45, 0x0F, 0xB7);
+ else
+ EMIT2(0x0F, 0xB7);
+ EMIT1(add_2reg(0xC0, dst_reg, dst_reg));
+ break;
+ case 32:
+ /* emit 'mov eax, eax' to clear upper 32-bits */
+ if (is_ereg(dst_reg))
+ EMIT1(0x45);
+ EMIT2(0x89, add_2reg(0xC0, dst_reg, dst_reg));
+ break;
+ case 64:
+ /* nop */
+ break;
+ }
break;
/* ST: *(u8*)(dst_reg + off) = imm */
Patches currently in stable-queue which might be from [email protected] are
queue-4.0/x86-bpf_jit-fix-from_be16-and-from_le16-32-instructions.patch
queue-4.0/x86-bpf_jit-fix-compilation-of-large-bpf-programs.patch
queue-4.0/net-sched-fix-call_rcu-race-on-classifier-module-unloads.patch
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