Commit 343f845b authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by David S. Miller

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: 89aa0758 ("net: sock: allow eBPF programs to be attached to sockets")
Signed-off-by: default avatarAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e3d8ecb7
......@@ -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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