From 7e639208e88d60abf83d48dfda4c0ad325a77b58 Mon Sep 17 00:00:00 2001 From: KP Singh Date: Wed, 4 Mar 2020 20:18:48 +0100 Subject: [PATCH] bpf: JIT helpers for fmod_ret progs * Split the invoke_bpf program to prepare for special handling of fmod_ret programs introduced in a subsequent patch. * Move the definition of emit_cond_near_jump and emit_nops as they are needed for fmod_ret. * Refactor branch target alignment into its own generic helper function i.e. emit_align. Signed-off-by: KP Singh Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Acked-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20200304191853.1529-3-kpsingh@chromium.org --- arch/x86/net/bpf_jit_comp.c | 148 +++++++++++++++++++++--------------- 1 file changed, 85 insertions(+), 63 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 15c7d28bc05c..d6349e930b06 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -1361,35 +1361,95 @@ static void restore_regs(const struct btf_func_model *m, u8 **prog, int nr_args, -(stack_size - i * 8)); } +static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog, + struct bpf_prog *p, int stack_size) +{ + u8 *prog = *pprog; + int cnt = 0; + + if (emit_call(&prog, __bpf_prog_enter, prog)) + return -EINVAL; + /* remember prog start time returned by __bpf_prog_enter */ + emit_mov_reg(&prog, true, BPF_REG_6, BPF_REG_0); + + /* arg1: lea rdi, [rbp - stack_size] */ + EMIT4(0x48, 0x8D, 0x7D, -stack_size); + /* arg2: progs[i]->insnsi for interpreter */ + if (!p->jited) + emit_mov_imm64(&prog, BPF_REG_2, + (long) p->insnsi >> 32, + (u32) (long) p->insnsi); + /* call JITed bpf program or interpreter */ + if (emit_call(&prog, p->bpf_func, prog)) + return -EINVAL; + + /* arg1: mov rdi, progs[i] */ + emit_mov_imm64(&prog, BPF_REG_1, (long) p >> 32, + (u32) (long) p); + /* arg2: mov rsi, rbx <- start time in nsec */ + emit_mov_reg(&prog, true, BPF_REG_2, BPF_REG_6); + if (emit_call(&prog, __bpf_prog_exit, prog)) + return -EINVAL; + + *pprog = prog; + return 0; +} + +static void emit_nops(u8 **pprog, unsigned int len) +{ + unsigned int i, noplen; + u8 *prog = *pprog; + int cnt = 0; + + while (len > 0) { + noplen = len; + + if (noplen > ASM_NOP_MAX) + noplen = ASM_NOP_MAX; + + for (i = 0; i < noplen; i++) + EMIT1(ideal_nops[noplen][i]); + len -= noplen; + } + + *pprog = prog; +} + +static void emit_align(u8 **pprog, u32 align) +{ + u8 *target, *prog = *pprog; + + target = PTR_ALIGN(prog, align); + if (target != prog) + emit_nops(&prog, target - prog); + + *pprog = prog; +} + +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); + if (!is_simm32(offset)) { + pr_err("Target %p is out of range\n", func); + return -EINVAL; + } + EMIT2_off32(0x0F, jmp_cond + 0x10, offset); + *pprog = prog; + return 0; +} + static int invoke_bpf(const struct btf_func_model *m, u8 **pprog, struct bpf_tramp_progs *tp, int stack_size) { + int i; u8 *prog = *pprog; - int cnt = 0, i; for (i = 0; i < tp->nr_progs; i++) { - if (emit_call(&prog, __bpf_prog_enter, prog)) - return -EINVAL; - /* remember prog start time returned by __bpf_prog_enter */ - emit_mov_reg(&prog, true, BPF_REG_6, BPF_REG_0); - - /* arg1: lea rdi, [rbp - stack_size] */ - EMIT4(0x48, 0x8D, 0x7D, -stack_size); - /* arg2: progs[i]->insnsi for interpreter */ - if (!tp->progs[i]->jited) - emit_mov_imm64(&prog, BPF_REG_2, - (long) tp->progs[i]->insnsi >> 32, - (u32) (long) tp->progs[i]->insnsi); - /* call JITed bpf program or interpreter */ - if (emit_call(&prog, tp->progs[i]->bpf_func, prog)) - return -EINVAL; - - /* arg1: mov rdi, progs[i] */ - emit_mov_imm64(&prog, BPF_REG_1, (long) tp->progs[i] >> 32, - (u32) (long) tp->progs[i]); - /* arg2: mov rsi, rbx <- start time in nsec */ - emit_mov_reg(&prog, true, BPF_REG_2, BPF_REG_6); - if (emit_call(&prog, __bpf_prog_exit, prog)) + if (invoke_bpf_prog(m, &prog, tp->progs[i], stack_size)) return -EINVAL; } *pprog = prog; @@ -1531,42 +1591,6 @@ int arch_prepare_bpf_trampoline(void *image, void *image_end, return prog - (u8 *)image; } -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); - if (!is_simm32(offset)) { - pr_err("Target %p is out of range\n", func); - return -EINVAL; - } - EMIT2_off32(0x0F, jmp_cond + 0x10, offset); - *pprog = prog; - return 0; -} - -static void emit_nops(u8 **pprog, unsigned int len) -{ - unsigned int i, noplen; - u8 *prog = *pprog; - int cnt = 0; - - while (len > 0) { - noplen = len; - - if (noplen > ASM_NOP_MAX) - noplen = ASM_NOP_MAX; - - for (i = 0; i < noplen; i++) - EMIT1(ideal_nops[noplen][i]); - len -= noplen; - } - - *pprog = prog; -} - static int emit_fallback_jump(u8 **pprog) { u8 *prog = *pprog; @@ -1589,7 +1613,7 @@ static int emit_fallback_jump(u8 **pprog) static int emit_bpf_dispatcher(u8 **pprog, int a, int b, s64 *progs) { - u8 *jg_reloc, *jg_target, *prog = *pprog; + u8 *jg_reloc, *prog = *pprog; int pivot, err, jg_bytes = 1, cnt = 0; s64 jg_offset; @@ -1644,9 +1668,7 @@ static int emit_bpf_dispatcher(u8 **pprog, int a, int b, s64 *progs) * Coding Rule 11: All branch targets should be 16-byte * aligned. */ - jg_target = PTR_ALIGN(prog, 16); - if (jg_target != prog) - emit_nops(&prog, jg_target - prog); + emit_align(&prog, 16); jg_offset = prog - jg_reloc; emit_code(jg_reloc - jg_bytes, jg_offset, jg_bytes);