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bpf, x86: Remove unused cnt increase from EMIT macro 

Removing unused cnt increase from EMIT macro together with cnt declarations.
This was introduced in commit [1] to ensure proper code generation. But that
code was removed in commit [2] and this extra code was left in.

  [1] b52f00e6a7 ("x86: bpf_jit: implement bpf_tail_call() helper")
  [2] ebf7d1f508 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT")

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210623112504.709856-1-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2021-06-23 13:25:04 +02:00 committed by Daniel Borkmann
parent 4b9718b5a2
commit ced50fc49f
1 changed files with 12 additions and 32 deletions
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44
arch/x86/net/bpf_jit_comp.c
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@ -31,7 +31,7 @@ static u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
}
#define EMIT(bytes, len) \
do { prog = emit_code(prog, bytes, len); cnt += len; } while (0)
do { prog = emit_code(prog, bytes, len); } while (0)
#define EMIT1(b1) EMIT(b1, 1)
#define EMIT2(b1, b2) EMIT((b1) + ((b2) << 8), 2)
@ -239,7 +239,6 @@ struct jit_context {
static void push_callee_regs(u8 **pprog, bool *callee_regs_used)
{
u8 *prog = *pprog;
int cnt = 0;
if (callee_regs_used[0])
EMIT1(0x53); /* push rbx */
@ -255,7 +254,6 @@ static void push_callee_regs(u8 **pprog, bool *callee_regs_used)
static void pop_callee_regs(u8 **pprog, bool *callee_regs_used)
{
u8 *prog = *pprog;
int cnt = 0;
if (callee_regs_used[3])
EMIT2(0x41, 0x5F); /* pop r15 */
@ -277,13 +275,12 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf,
bool tail_call_reachable, bool is_subprog)
{
u8 *prog = *pprog;
int cnt = X86_PATCH_SIZE;
/* BPF trampoline can be made to work without these nops,
* but let's waste 5 bytes for now and optimize later
*/
memcpy(prog, x86_nops[5], cnt);
prog += cnt;
memcpy(prog, x86_nops[5], X86_PATCH_SIZE);
prog += X86_PATCH_SIZE;
if (!ebpf_from_cbpf) {
if (tail_call_reachable && !is_subprog)
EMIT2(0x31, 0xC0); /* xor eax, eax */
@ -303,7 +300,6 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf,
static int emit_patch(u8 **pprog, void *func, void *ip, u8 opcode)
{
u8 *prog = *pprog;
int cnt = 0;
s64 offset;
offset = func - (ip + X86_PATCH_SIZE);
@ -423,7 +419,6 @@ static void emit_bpf_tail_call_indirect(u8 **pprog, bool *callee_regs_used,
int off1 = 42;
int off2 = 31;
int off3 = 9;
int cnt = 0;
/* count the additional bytes used for popping callee regs from stack
* that need to be taken into account for each of the offsets that
@ -513,7 +508,6 @@ static void emit_bpf_tail_call_direct(struct bpf_jit_poke_descriptor *poke,
int pop_bytes = 0;
int off1 = 20;
int poke_off;
int cnt = 0;
/* count the additional bytes used for popping callee regs to stack
* that need to be taken into account for jump offset that is used for
@ -615,7 +609,6 @@ static void emit_mov_imm32(u8 **pprog, bool sign_propagate,
{
u8 *prog = *pprog;
u8 b1, b2, b3;
int cnt = 0;
/*
* Optimization: if imm32 is positive, use 'mov %eax, imm32'
@ -655,7 +648,6 @@ static void emit_mov_imm64(u8 **pprog, u32 dst_reg,
const u32 imm32_hi, const u32 imm32_lo)
{
u8 *prog = *pprog;
int cnt = 0;
if (is_uimm32(((u64)imm32_hi << 32) | (u32)imm32_lo)) {
/*
@ -678,7 +670,6 @@ static void emit_mov_imm64(u8 **pprog, u32 dst_reg,
static void emit_mov_reg(u8 **pprog, bool is64, u32 dst_reg, u32 src_reg)
{
u8 *prog = *pprog;
int cnt = 0;
if (is64) {
/* mov dst, src */
@ -697,7 +688,6 @@ static void emit_mov_reg(u8 **pprog, bool is64, u32 dst_reg, u32 src_reg)
static void emit_insn_suffix(u8 **pprog, u32 ptr_reg, u32 val_reg, int off)
{
u8 *prog = *pprog;
int cnt = 0;
if (is_imm8(off)) {
/* 1-byte signed displacement.
@ -720,7 +710,6 @@ static void emit_insn_suffix(u8 **pprog, u32 ptr_reg, u32 val_reg, int off)
static void maybe_emit_mod(u8 **pprog, u32 dst_reg, u32 src_reg, bool is64)
{
u8 *prog = *pprog;
int cnt = 0;
if (is64)
EMIT1(add_2mod(0x48, dst_reg, src_reg));
@ -733,7 +722,6 @@ static void maybe_emit_mod(u8 **pprog, u32 dst_reg, u32 src_reg, bool is64)
static void emit_ldx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off)
{
u8 *prog = *pprog;
int cnt = 0;
switch (size) {
case BPF_B:
@ -764,7 +752,6 @@ static void emit_ldx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off)
static void emit_stx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off)
{
u8 *prog = *pprog;
int cnt = 0;
switch (size) {
case BPF_B:
@ -799,7 +786,6 @@ static int emit_atomic(u8 **pprog, u8 atomic_op,
u32 dst_reg, u32 src_reg, s16 off, u8 bpf_size)
{
u8 *prog = *pprog;
int cnt = 0;
EMIT1(0xF0); /* lock prefix */
@ -869,10 +855,10 @@ static void detect_reg_usage(struct bpf_insn *insn, int insn_cnt,
}
}
static int emit_nops(u8 **pprog, int len)
static void emit_nops(u8 **pprog, int len)
{
u8 *prog = *pprog;
int i, noplen, cnt = 0;
int i, noplen;
while (len > 0) {
noplen = len;
@ -886,8 +872,6 @@ static int emit_nops(u8 **pprog, int len)
}
*pprog = prog;
return cnt;
}
#define INSN_SZ_DIFF (((addrs[i] - addrs[i - 1]) - (prog - temp)))
@ -902,7 +886,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
bool tail_call_seen = false;
bool seen_exit = false;
u8 temp[BPF_MAX_INSN_SIZE + BPF_INSN_SAFETY];
int i, cnt = 0, excnt = 0;
int i, excnt = 0;
int ilen, proglen = 0;
u8 *prog = temp;
int err;
@ -1576,7 +1560,7 @@ emit_cond_jmp: /* Convert BPF opcode to x86 */
nops);
return -EFAULT;
}
cnt += emit_nops(&prog, nops);
emit_nops(&prog, nops);
}
EMIT2(jmp_cond, jmp_offset);
} else if (is_simm32(jmp_offset)) {
@ -1622,7 +1606,7 @@ emit_cond_jmp: /* Convert BPF opcode to x86 */
nops);
return -EFAULT;
}
cnt += emit_nops(&prog, nops);
emit_nops(&prog, nops);
}
break;
}
@ -1647,7 +1631,7 @@ emit_jmp:
nops);
return -EFAULT;
}
cnt += emit_nops(&prog, INSN_SZ_DIFF - 2);
emit_nops(&prog, INSN_SZ_DIFF - 2);
}
EMIT2(0xEB, jmp_offset);
} else if (is_simm32(jmp_offset)) {
@ -1754,7 +1738,6 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
{
u8 *prog = *pprog;
u8 *jmp_insn;
int cnt = 0;
/* arg1: mov rdi, progs[i] */
emit_mov_imm64(&prog, BPF_REG_1, (long) p >> 32, (u32) (long) p);
@ -1822,7 +1805,6 @@ static void emit_align(u8 **pprog, u32 align)
static int emit_cond_near_jump(u8 **pprog, void *func, void *ip, u8 jmp_cond)
{
u8 *prog = *pprog;
int cnt = 0;
s64 offset;
offset = func - (ip + 2 + 4);
@ -1854,7 +1836,7 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
u8 **branches)
{
u8 *prog = *pprog;
int i, cnt = 0;
int i;
/* The first fmod_ret program will receive a garbage return value.
* Set this to 0 to avoid confusing the program.
@ -1950,7 +1932,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
struct bpf_tramp_progs *tprogs,
void *orig_call)
{
int ret, i, cnt = 0, nr_args = m->nr_args;
int ret, i, nr_args = m->nr_args;
int stack_size = nr_args * 8;
struct bpf_tramp_progs *fentry = &tprogs[BPF_TRAMP_FENTRY];
struct bpf_tramp_progs *fexit = &tprogs[BPF_TRAMP_FEXIT];
@ -2095,8 +2077,6 @@ static int emit_fallback_jump(u8 **pprog)
*/
err = emit_jump(&prog, __x86_indirect_thunk_rdx, prog);
#else
int cnt = 0;
EMIT2(0xFF, 0xE2); /* jmp rdx */
#endif
*pprog = prog;
@ -2106,7 +2086,7 @@ static int emit_fallback_jump(u8 **pprog)
static int emit_bpf_dispatcher(u8 **pprog, int a, int b, s64 *progs)
{
u8 *jg_reloc, *prog = *pprog;
int pivot, err, jg_bytes = 1, cnt = 0;
int pivot, err, jg_bytes = 1;
s64 jg_offset;
if (a == b) {