From ced50fc49f3bde2892c3d7fad7b3b6bfbc6ef90e Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 23 Jun 2021 13:25:04 +0200 Subject: [PATCH] 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] b52f00e6a715 ("x86: bpf_jit: implement bpf_tail_call() helper") [2] ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT") Signed-off-by: Jiri Olsa Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20210623112504.709856-1-jolsa@kernel.org --- arch/x86/net/bpf_jit_comp.c | 44 ++++++++++++-------------------------------- 1 file changed, 12 insertions(+), 32 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 2a2e290fa5d8..db1e83813db5 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -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) { -- 2.11.0