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authorDaniel Borkmann <daniel@iogearbox.net>2019-11-24 01:39:42 +0100
committerAlexei Starovoitov <ast@kernel.org>2019-11-24 17:12:11 -0800
commitb553a6ec570044fc1ae300c6fb24f9ce204c5894 (patch)
tree6121de7c1e38050fd9d4d46480ae6fddf9d585b2 /arch/x86/net
parentf9a7cf6eb17cd0110c8c47d9e7969fc2716e5772 (diff)
downloadlinux-b553a6ec570044fc1ae300c6fb24f9ce204c5894.tar.bz2
bpf: Simplify __bpf_arch_text_poke poke type handling
Given that we have BPF_MOD_NOP_TO_{CALL,JUMP}, BPF_MOD_{CALL,JUMP}_TO_NOP and BPF_MOD_{CALL,JUMP}_TO_{CALL,JUMP} poke types and that we also pass in old_addr as well as new_addr, it's a bit redundant and unnecessarily complicates __bpf_arch_text_poke() itself since we can derive the same from the *_addr that were passed in. Hence simplify and use BPF_MOD_{CALL,JUMP} as types which also allows to clean up call-sites. In addition to that, __bpf_arch_text_poke() currently verifies that text matches expected old_insn before we invoke text_poke_bp(). Also add a check on new_insn and skip rewrite if it already matches. Reason why this is rather useful is that it avoids making any special casing in prog_array_map_poke_run() when old and new prog were NULL and has the benefit that also for this case we perform a check on text whether it really matches our expectations. Suggested-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/fcb00a2b0b288d6c73de4ef58116a821c8fe8f2f.1574555798.git.daniel@iogearbox.net
Diffstat (limited to 'arch/x86/net')
-rw-r--r--arch/x86/net/bpf_jit_comp.c85
1 files changed, 25 insertions, 60 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 15615c94804f..b8be18427277 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -269,76 +269,42 @@ static int __bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
void *old_addr, void *new_addr,
const bool text_live)
{
- int (*emit_patch_fn)(u8 **pprog, void *func, void *ip);
const u8 *nop_insn = ideal_nops[NOP_ATOMIC5];
- u8 old_insn[X86_PATCH_SIZE] = {};
- u8 new_insn[X86_PATCH_SIZE] = {};
+ u8 old_insn[X86_PATCH_SIZE];
+ u8 new_insn[X86_PATCH_SIZE];
u8 *prog;
int ret;
- switch (t) {
- case BPF_MOD_NOP_TO_CALL ... BPF_MOD_CALL_TO_NOP:
- emit_patch_fn = emit_call;
- break;
- case BPF_MOD_NOP_TO_JUMP ... BPF_MOD_JUMP_TO_NOP:
- emit_patch_fn = emit_jump;
- break;
- default:
- return -ENOTSUPP;
+ memcpy(old_insn, nop_insn, X86_PATCH_SIZE);
+ if (old_addr) {
+ prog = old_insn;
+ ret = t == BPF_MOD_CALL ?
+ emit_call(&prog, old_addr, ip) :
+ emit_jump(&prog, old_addr, ip);
+ if (ret)
+ return ret;
}
- switch (t) {
- case BPF_MOD_NOP_TO_CALL:
- case BPF_MOD_NOP_TO_JUMP:
- if (!old_addr && new_addr) {
- memcpy(old_insn, nop_insn, X86_PATCH_SIZE);
-
- prog = new_insn;
- ret = emit_patch_fn(&prog, new_addr, ip);
- if (ret)
- return ret;
- break;
- }
- return -ENXIO;
- case BPF_MOD_CALL_TO_CALL:
- case BPF_MOD_JUMP_TO_JUMP:
- if (old_addr && new_addr) {
- prog = old_insn;
- ret = emit_patch_fn(&prog, old_addr, ip);
- if (ret)
- return ret;
-
- prog = new_insn;
- ret = emit_patch_fn(&prog, new_addr, ip);
- if (ret)
- return ret;
- break;
- }
- return -ENXIO;
- case BPF_MOD_CALL_TO_NOP:
- case BPF_MOD_JUMP_TO_NOP:
- if (old_addr && !new_addr) {
- memcpy(new_insn, nop_insn, X86_PATCH_SIZE);
-
- prog = old_insn;
- ret = emit_patch_fn(&prog, old_addr, ip);
- if (ret)
- return ret;
- break;
- }
- return -ENXIO;
- default:
- return -ENOTSUPP;
+ memcpy(new_insn, nop_insn, X86_PATCH_SIZE);
+ if (new_addr) {
+ prog = new_insn;
+ ret = t == BPF_MOD_CALL ?
+ emit_call(&prog, new_addr, ip) :
+ emit_jump(&prog, new_addr, ip);
+ if (ret)
+ return ret;
}
ret = -EBUSY;
mutex_lock(&text_mutex);
if (memcmp(ip, old_insn, X86_PATCH_SIZE))
goto out;
- if (text_live)
- text_poke_bp(ip, new_insn, X86_PATCH_SIZE, NULL);
- else
- memcpy(ip, new_insn, X86_PATCH_SIZE);
+ if (memcmp(ip, new_insn, X86_PATCH_SIZE)) {
+ if (text_live)
+ text_poke_bp(ip, new_insn, X86_PATCH_SIZE, NULL);
+ else
+ memcpy(ip, new_insn, X86_PATCH_SIZE);
+ }
ret = 0;
out:
mutex_unlock(&text_mutex);
@@ -465,7 +431,6 @@ static void emit_bpf_tail_call_direct(struct bpf_jit_poke_descriptor *poke,
static void bpf_tail_call_direct_fixup(struct bpf_prog *prog)
{
- static const enum bpf_text_poke_type type = BPF_MOD_NOP_TO_JUMP;
struct bpf_jit_poke_descriptor *poke;
struct bpf_array *array;
struct bpf_prog *target;
@@ -490,7 +455,7 @@ static void bpf_tail_call_direct_fixup(struct bpf_prog *prog)
* read-only. Both modifications on the given image
* are under text_mutex to avoid interference.
*/
- ret = __bpf_arch_text_poke(poke->ip, type, NULL,
+ ret = __bpf_arch_text_poke(poke->ip, BPF_MOD_JUMP, NULL,
(u8 *)target->bpf_func +
poke->adj_off, false);
BUG_ON(ret < 0);