Merge branch 'bpf: Avoid unnecessary deadlock detection and failure in task storage'

Martin KaFai Lau says:

====================

From: Martin KaFai Lau <martin.lau@kernel.org>

The commit bc235cdb423a ("bpf: Prevent deadlock from recursive bpf_task_storage_[get|delete]")
added deadlock detection to avoid a tracing program from recurring
on the bpf_task_storage_{get,delete}() helpers.  These helpers acquire
a spin lock and it will lead to deadlock.

It is unnecessary for the bpf_lsm and bpf_iter programs which do
not recur.  The situation is the same as the existing
bpf_pid_task_storage_{lookup,delete}_elem() which are
used in the syscall and they also do not have deadlock detection.

This set is to add new bpf_task_storage_{get,delete}() helper proto
without the deadlock detection.  The set also removes the prog->active
check from the bpf_lsm and bpf_iter program.  Please see the individual
patch for details.
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 2 insertions, 17 deletions

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index d7dd8e0db8da..36ffe67ad6e5 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1894,10 +1894,6 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
 			   struct bpf_tramp_link *l, int stack_size,
 			   int run_ctx_off, bool save_ret)
 {
-	void (*exit)(struct bpf_prog *prog, u64 start,
-		     struct bpf_tramp_run_ctx *run_ctx) = __bpf_prog_exit;
-	u64 (*enter)(struct bpf_prog *prog,
-		     struct bpf_tramp_run_ctx *run_ctx) = __bpf_prog_enter;
 	u8 *prog = *pprog;
 	u8 *jmp_insn;
 	int ctx_cookie_off = offsetof(struct bpf_tramp_run_ctx, bpf_cookie);
@@ -1916,23 +1912,12 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
 	 */
 	emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_1, -run_ctx_off + ctx_cookie_off);
 
-	if (p->aux->sleepable) {
-		enter = __bpf_prog_enter_sleepable;
-		exit = __bpf_prog_exit_sleepable;
-	} else if (p->type == BPF_PROG_TYPE_STRUCT_OPS) {
-		enter = __bpf_prog_enter_struct_ops;
-		exit = __bpf_prog_exit_struct_ops;
-	} else if (p->expected_attach_type == BPF_LSM_CGROUP) {
-		enter = __bpf_prog_enter_lsm_cgroup;
-		exit = __bpf_prog_exit_lsm_cgroup;
-	}
-
 	/* arg1: mov rdi, progs[i] */
 	emit_mov_imm64(&prog, BPF_REG_1, (long) p >> 32, (u32) (long) p);
 	/* arg2: lea rsi, [rbp - ctx_cookie_off] */
 	EMIT4(0x48, 0x8D, 0x75, -run_ctx_off);
 
-	if (emit_call(&prog, enter, prog))
+	if (emit_call(&prog, bpf_trampoline_enter(p), prog))
 		return -EINVAL;
 	/* remember prog start time returned by __bpf_prog_enter */
 	emit_mov_reg(&prog, true, BPF_REG_6, BPF_REG_0);
@@ -1977,7 +1962,7 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
 	emit_mov_reg(&prog, true, BPF_REG_2, BPF_REG_6);
 	/* arg3: lea rdx, [rbp - run_ctx_off] */
 	EMIT4(0x48, 0x8D, 0x55, -run_ctx_off);
-	if (emit_call(&prog, exit, prog))
+	if (emit_call(&prog, bpf_trampoline_exit(p), prog))
 		return -EINVAL;
 
 	*pprog = prog;