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bpf: Optimize recursion detection for arm64 #6287

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bpf: Optimize recursion detection for arm64 #6287

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4 changes: 3 additions & 1 deletion include/linux/bpf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1728,6 +1728,8 @@ struct bpf_prog_aux {
struct bpf_stream stream[2];
};

#define BPF_NR_CONTEXTS 4

struct bpf_prog {
u16 pages; /* Number of allocated pages */
u16 jited:1, /* Is our filter JIT'ed? */
Expand All @@ -1754,7 +1756,7 @@ struct bpf_prog {
u8 tag[BPF_TAG_SIZE];
};
struct bpf_prog_stats __percpu *stats;
int __percpu *active;
u8 __percpu *active; /* u8[BPF_NR_CONTEXTS] for rerecursion protection */
unsigned int (*bpf_func)(const void *ctx,
const struct bpf_insn *insn);
struct bpf_prog_aux *aux; /* Auxiliary fields */
Expand Down
3 changes: 2 additions & 1 deletion kernel/bpf/core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -112,7 +112,8 @@ struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flag
vfree(fp);
return NULL;
}
fp->active = alloc_percpu_gfp(int, bpf_memcg_flags(GFP_KERNEL | gfp_extra_flags));
fp->active = __alloc_percpu_gfp(sizeof(u8[BPF_NR_CONTEXTS]), 8,
bpf_memcg_flags(GFP_KERNEL | gfp_extra_flags));
if (!fp->active) {
vfree(fp);
kfree(aux);
Expand Down
22 changes: 18 additions & 4 deletions kernel/bpf/trampoline.c
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Original file line number Diff line number Diff line change
Expand Up @@ -899,11 +899,15 @@ static __always_inline u64 notrace bpf_prog_start_time(void)
static u64 notrace __bpf_prog_enter_recur(struct bpf_prog *prog, struct bpf_tramp_run_ctx *run_ctx)
__acquires(RCU)
{
u8 rctx = interrupt_context_level();
u8 *active;

rcu_read_lock_dont_migrate();

run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx);

if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) {
active = this_cpu_ptr(prog->active);
if (unlikely(++active[rctx] != 1)) {
bpf_prog_inc_misses_counter(prog);
if (prog->aux->recursion_detected)
prog->aux->recursion_detected(prog);
Expand Down Expand Up @@ -944,10 +948,13 @@ static void notrace __bpf_prog_exit_recur(struct bpf_prog *prog, u64 start,
struct bpf_tramp_run_ctx *run_ctx)
__releases(RCU)
{
u8 rctx = interrupt_context_level();
u8 *active = this_cpu_ptr(prog->active);

bpf_reset_run_ctx(run_ctx->saved_run_ctx);

update_prog_stats(prog, start);
this_cpu_dec(*(prog->active));
active[rctx]--;
rcu_read_unlock_migrate();
}

Expand Down Expand Up @@ -977,13 +984,17 @@ static void notrace __bpf_prog_exit_lsm_cgroup(struct bpf_prog *prog, u64 start,
u64 notrace __bpf_prog_enter_sleepable_recur(struct bpf_prog *prog,
struct bpf_tramp_run_ctx *run_ctx)
{
u8 rctx = interrupt_context_level();
u8 *active;

rcu_read_lock_trace();
migrate_disable();
might_fault();

run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx);

if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) {
active = this_cpu_ptr(prog->active);
if (unlikely(++active[rctx] != 1)) {
bpf_prog_inc_misses_counter(prog);
if (prog->aux->recursion_detected)
prog->aux->recursion_detected(prog);
Expand All @@ -995,10 +1006,13 @@ u64 notrace __bpf_prog_enter_sleepable_recur(struct bpf_prog *prog,
void notrace __bpf_prog_exit_sleepable_recur(struct bpf_prog *prog, u64 start,
struct bpf_tramp_run_ctx *run_ctx)
{
u8 rctx = interrupt_context_level();
u8 *active = this_cpu_ptr(prog->active);

bpf_reset_run_ctx(run_ctx->saved_run_ctx);

update_prog_stats(prog, start);
this_cpu_dec(*(prog->active));
active[rctx]--;
migrate_enable();
rcu_read_unlock_trace();
}
Expand Down
11 changes: 7 additions & 4 deletions kernel/trace/bpf_trace.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2059,14 +2059,18 @@ static __always_inline
void __bpf_trace_run(struct bpf_raw_tp_link *link, u64 *args)
{
struct bpf_prog *prog = link->link.prog;
u8 rctx = interrupt_context_level();
struct bpf_run_ctx *old_run_ctx;
struct bpf_trace_run_ctx run_ctx;
u8 *active;

cant_sleep();
if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) {
active = this_cpu_ptr(prog->active);
if (unlikely(active[rctx])) {
bpf_prog_inc_misses_counter(prog);
goto out;
return;
}
active[rctx]++;

run_ctx.bpf_cookie = link->cookie;
old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
Expand All @@ -2076,8 +2080,7 @@ void __bpf_trace_run(struct bpf_raw_tp_link *link, u64 *args)
rcu_read_unlock();

bpf_reset_run_ctx(old_run_ctx);
out:
this_cpu_dec(*(prog->active));
active[rctx]--;
}

#define UNPACK(...) __VA_ARGS__
Expand Down
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