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bpf: take advantage of stack_depth tracking in x64 JIT

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Take advantage of stack_depth tracking in x64 JIT.
Round up allocated stack by 8 bytes to make sure it stays aligned
for functions called from JITed bpf program.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2017-05-30 13:31:35 -07:00 committed by David S. Miller
parent 177366bf7c
commit 2960ae48c4
1 changed files with 5 additions and 4 deletions
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9
arch/x86/net/bpf_jit_comp.c
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@ -206,7 +206,7 @@ struct jit_context {
/* emit x64 prologue code for BPF program and check it's size. /* emit x64 prologue code for BPF program and check it's size.
* bpf_tail_call helper will skip it while jumping into another program * bpf_tail_call helper will skip it while jumping into another program
*/ */
static void emit_prologue(u8 **pprog) static void emit_prologue(u8 **pprog, u32 stack_depth)
{ {
u8 *prog = *pprog; u8 *prog = *pprog;
int cnt = 0; int cnt = 0;
@ -214,8 +214,9 @@ static void emit_prologue(u8 **pprog)
EMIT1(0x55); /* push rbp */ EMIT1(0x55); /* push rbp */
EMIT3(0x48, 0x89, 0xE5); /* mov rbp,rsp */ EMIT3(0x48, 0x89, 0xE5); /* mov rbp,rsp */
/* sub rsp, MAX_BPF_STACK + AUX_STACK_SPACE */ /* sub rsp, rounded_stack_depth + AUX_STACK_SPACE */
EMIT3_off32(0x48, 0x81, 0xEC, MAX_BPF_STACK + AUX_STACK_SPACE); EMIT3_off32(0x48, 0x81, 0xEC,
round_up(stack_depth, 8) + AUX_STACK_SPACE);
/* sub rbp, AUX_STACK_SPACE */ /* sub rbp, AUX_STACK_SPACE */
EMIT4(0x48, 0x83, 0xED, AUX_STACK_SPACE); EMIT4(0x48, 0x83, 0xED, AUX_STACK_SPACE);
@ -363,7 +364,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
int proglen = 0; int proglen = 0;
u8 *prog = temp; u8 *prog = temp;
emit_prologue(&prog); emit_prologue(&prog, bpf_prog->aux->stack_depth);
if (seen_ld_abs) if (seen_ld_abs)
emit_load_skb_data_hlen(&prog); emit_load_skb_data_hlen(&prog);