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authorAlexei Starovoitov <ast@plumgrid.com>2015-05-11 23:25:16 -0700
committerDavid S. Miller <davem@davemloft.net>2015-05-12 23:13:08 -0400
commit343f845b375989f1753f605902931fa939aa2223 (patch)
treefd2f63ee5b1cf7921993a4f9a0f35c80ac2e5485 /arch
parente3d8ecb70e16412b14fb11c1b68ecb533bd4ea64 (diff)
x86: bpf_jit: fix FROM_BE16 and FROM_LE16/32 instructions
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 <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/net/bpf_jit_comp.c28
1 files changed, 28 insertions, 0 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 987514396c1e..99f76103c6b7 100644
--- 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_prog, int *addrs, u8 *image,
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_prog, int *addrs, u8 *image,
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 */

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