diff options
Diffstat (limited to 'arch/x86/net/bpf_jit_comp.c')
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index b8be18427277..4c8a2d1f8470 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -10,10 +10,12 @@ #include <linux/if_vlan.h> #include <linux/bpf.h> #include <linux/memory.h> +#include <linux/sort.h> #include <asm/extable.h> #include <asm/set_memory.h> #include <asm/nospec-branch.h> #include <asm/text-patching.h> +#include <asm/asm-prototypes.h> static u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len) { @@ -1530,6 +1532,154 @@ int arch_prepare_bpf_trampoline(void *image, struct btf_func_model *m, u32 flags return 0; } +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; + int err = 0; + +#ifdef CONFIG_RETPOLINE + /* Note that this assumes the the compiler uses external + * thunks for indirect calls. Both clang and GCC use the same + * naming convention for external thunks. + */ + err = emit_jump(&prog, __x86_indirect_thunk_rdx, prog); +#else + int cnt = 0; + + EMIT2(0xFF, 0xE2); /* jmp rdx */ +#endif + *pprog = prog; + return err; +} + +static int emit_bpf_dispatcher(u8 **pprog, int a, int b, s64 *progs) +{ + u8 *jg_reloc, *jg_target, *prog = *pprog; + int pivot, err, jg_bytes = 1, cnt = 0; + s64 jg_offset; + + if (a == b) { + /* Leaf node of recursion, i.e. not a range of indices + * anymore. + */ + EMIT1(add_1mod(0x48, BPF_REG_3)); /* cmp rdx,func */ + if (!is_simm32(progs[a])) + return -1; + EMIT2_off32(0x81, add_1reg(0xF8, BPF_REG_3), + progs[a]); + err = emit_cond_near_jump(&prog, /* je func */ + (void *)progs[a], prog, + X86_JE); + if (err) + return err; + + err = emit_fallback_jump(&prog); /* jmp thunk/indirect */ + if (err) + return err; + + *pprog = prog; + return 0; + } + + /* Not a leaf node, so we pivot, and recursively descend into + * the lower and upper ranges. + */ + pivot = (b - a) / 2; + EMIT1(add_1mod(0x48, BPF_REG_3)); /* cmp rdx,func */ + if (!is_simm32(progs[a + pivot])) + return -1; + EMIT2_off32(0x81, add_1reg(0xF8, BPF_REG_3), progs[a + pivot]); + + if (pivot > 2) { /* jg upper_part */ + /* Require near jump. */ + jg_bytes = 4; + EMIT2_off32(0x0F, X86_JG + 0x10, 0); + } else { + EMIT2(X86_JG, 0); + } + jg_reloc = prog; + + err = emit_bpf_dispatcher(&prog, a, a + pivot, /* emit lower_part */ + progs); + if (err) + return err; + + /* From Intel 64 and IA-32 Architectures Optimization + * Reference Manual, 3.4.1.4 Code Alignment, Assembly/Compiler + * 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); + jg_offset = prog - jg_reloc; + emit_code(jg_reloc - jg_bytes, jg_offset, jg_bytes); + + err = emit_bpf_dispatcher(&prog, a + pivot + 1, /* emit upper_part */ + b, progs); + if (err) + return err; + + *pprog = prog; + return 0; +} + +static int cmp_ips(const void *a, const void *b) +{ + const s64 *ipa = a; + const s64 *ipb = b; + + if (*ipa > *ipb) + return 1; + if (*ipa < *ipb) + return -1; + return 0; +} + +int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, int num_funcs) +{ + u8 *prog = image; + + sort(funcs, num_funcs, sizeof(funcs[0]), cmp_ips, NULL); + return emit_bpf_dispatcher(&prog, 0, num_funcs - 1, funcs); +} + struct x64_jit_data { struct bpf_binary_header *header; int *addrs; |