BPF trampolines will create a bpf_trace_run_ctx on their stacks, and
set/reset the current bpf_run_ctx whenever calling/returning from a
bpf_prog.
Signed-off-by: Kui-Feng Lee <kuifeng@xxxxxx>
---
arch/x86/net/bpf_jit_comp.c | 32 ++++++++++++++++++++++++++++++++
include/linux/bpf.h | 12 ++++++++----
kernel/bpf/syscall.c | 4 ++--
kernel/bpf/trampoline.c | 21 +++++++++++++++++----
4 files changed, 59 insertions(+), 10 deletions(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 1228e6e6a420..29775a475513 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1748,10 +1748,33 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
{
u8 *prog = *pprog;
u8 *jmp_insn;
+ int ctx_cookie_off = offsetof(struct bpf_trace_run_ctx, bpf_cookie);
struct bpf_prog *p = l->prog;
+ EMIT1(0x52); /* push rdx */
+
+ /* mov rdi, 0 */
+ emit_mov_imm64(&prog, BPF_REG_1, 0, 0);
+
+ /* Prepare struct bpf_trace_run_ctx.
+ * sub rsp, sizeof(struct bpf_trace_run_ctx)
+ * mov rax, rsp
+ * mov QWORD PTR [rax + ctx_cookie_off], rdi
+ */
+ EMIT4(0x48, 0x83, 0xEC, sizeof(struct bpf_trace_run_ctx));
+ EMIT3(0x48, 0x89, 0xE0);
+ EMIT4(0x48, 0x89, 0x78, ctx_cookie_off);
+
+ /* mov rdi, rsp */
+ EMIT3(0x48, 0x89, 0xE7);
+ /* mov QWORD PTR [rdi + sizeof(struct bpf_trace_run_ctx)], rax */
+ emit_stx(&prog, BPF_DW, BPF_REG_1, BPF_REG_0, sizeof(struct bpf_trace_run_ctx));
+
/* arg1: mov rdi, progs[i] */
emit_mov_imm64(&prog, BPF_REG_1, (long) p >> 32, (u32) (long) p);
+ /* arg2: mov rsi, rsp (struct bpf_run_ctx *) */
+ EMIT3(0x48, 0x89, 0xE6);
+
if (emit_call(&prog,
p->aux->sleepable ? __bpf_prog_enter_sleepable :
__bpf_prog_enter, prog))
@@ -1797,11 +1820,20 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
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);
+ /* arg3: mov rdx, rsp (struct bpf_run_ctx *) */
+ EMIT3(0x48, 0x89, 0xE2);
if (emit_call(&prog,
p->aux->sleepable ? __bpf_prog_exit_sleepable :
__bpf_prog_exit, prog))
return -EINVAL;
+ /* pop struct bpf_trace_run_ctx
+ * add rsp, sizeof(struct bpf_trace_run_ctx)
+ */
+ EMIT4(0x48, 0x83, 0xC4, sizeof(struct bpf_trace_run_ctx));
+
+ EMIT1(0x5A); /* pop rdx */
+
*pprog = prog;
return 0;
}
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 3dcae8550c21..d20a23953696 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -681,6 +681,8 @@ struct bpf_tramp_links {
int nr_links;
};
+struct bpf_trace_run_ctx;
+
/* Different use cases for BPF trampoline:
* 1. replace nop at the function entry (kprobe equivalent)
* flags = BPF_TRAMP_F_RESTORE_REGS
@@ -707,10 +709,11 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *tr, void *image, void *i
struct bpf_tramp_links *tlinks,
void *orig_call);
/* these two functions are called from generated trampoline */
-u64 notrace __bpf_prog_enter(struct bpf_prog *prog);
-void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start);
-u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog);
-void notrace __bpf_prog_exit_sleepable(struct bpf_prog *prog, u64 start);
+u64 notrace __bpf_prog_enter(struct bpf_prog *prog, struct bpf_trace_run_ctx *run_ctx);
+void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start, struct bpf_trace_run_ctx *run_ctx);
+u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog, struct bpf_trace_run_ctx *run_ctx);
+void notrace __bpf_prog_exit_sleepable(struct bpf_prog *prog, u64 start,
+ struct bpf_trace_run_ctx *run_ctx);
void notrace __bpf_tramp_enter(struct bpf_tramp_image *tr);
void notrace __bpf_tramp_exit(struct bpf_tramp_image *tr);
@@ -1291,6 +1294,7 @@ struct bpf_cg_run_ctx {
struct bpf_trace_run_ctx {
struct bpf_run_ctx run_ctx;
u64 bpf_cookie;
+ struct bpf_run_ctx *saved_run_ctx;
};
static inline struct bpf_run_ctx *bpf_set_run_ctx(struct bpf_run_ctx *new_ctx)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index fecfc803785d..a289ef55ea17 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4793,13 +4793,13 @@ BPF_CALL_3(bpf_sys_bpf, int, cmd, union bpf_attr *, attr, u32, attr_size)
return -EINVAL;
}
- if (!__bpf_prog_enter_sleepable(prog)) {
+ if (!__bpf_prog_enter_sleepable(prog, NULL)) {
/* recursion detected */
bpf_prog_put(prog);
return -EBUSY;
}
attr->test.retval = bpf_prog_run(prog, (void *) (long) attr->test.ctx_in);
- __bpf_prog_exit_sleepable(prog, 0 /* bpf_prog_run does runtime stats */);
+ __bpf_prog_exit_sleepable(prog, 0 /* bpf_prog_run does runtime stats */, NULL);
bpf_prog_put(prog);
return 0;
#endif
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 54c695d49ec9..0b050aa2f159 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -580,9 +580,12 @@ static void notrace inc_misses_counter(struct bpf_prog *prog)
* [2..MAX_U64] - execute bpf prog and record execution time.
* This is start time.
*/
-u64 notrace __bpf_prog_enter(struct bpf_prog *prog)
+u64 notrace __bpf_prog_enter(struct bpf_prog *prog, struct bpf_trace_run_ctx *run_ctx)
__acquires(RCU)
{
+ if (run_ctx)
+ run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx);
+
rcu_read_lock();
migrate_disable();
if (unlikely(__this_cpu_inc_return(*(prog->active)) != 1)) {
@@ -614,17 +617,23 @@ static void notrace update_prog_stats(struct bpf_prog *prog,
}
}
-void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start)
+void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start, struct bpf_trace_run_ctx *run_ctx)
__releases(RCU)
{
+ if (run_ctx)
+ bpf_reset_run_ctx(run_ctx->saved_run_ctx);
+
update_prog_stats(prog, start);
__this_cpu_dec(*(prog->active));
migrate_enable();
rcu_read_unlock();
}
-u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog)
+u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog, struct bpf_trace_run_ctx *run_ctx)
{
+ if (run_ctx)
+ run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx);
+
rcu_read_lock_trace();
migrate_disable();
might_fault();
@@ -635,8 +644,12 @@ u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog)
return bpf_prog_start_time();
}
-void notrace __bpf_prog_exit_sleepable(struct bpf_prog *prog, u64 start)
+void notrace __bpf_prog_exit_sleepable(struct bpf_prog *prog, u64 start,
+ struct bpf_trace_run_ctx *run_ctx)
{
+ if (run_ctx)
+ bpf_reset_run_ctx(run_ctx->saved_run_ctx);
+
update_prog_stats(prog, start);
__this_cpu_dec(*(prog->active));
migrate_enable();
--
2.30.2
