[RFC PATCH bpf-next 4/7] bpf, x86: Make program update work for trampoline ops

[Jordan Rife]

Use update_prog in place of current link prog when link matches
update_link.

Signed-off-by: Jordan Rife <jordan at jrife.io>
---
 arch/x86/net/bpf_jit_comp.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 36a0d4db9f68..2b3ea20b39b9 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -2956,15 +2956,13 @@ static void restore_regs(const struct btf_func_model *m, u8 **prog,
 }
 
 static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
-			   struct bpf_tramp_link *l, int stack_size,
+			   struct bpf_prog *p, u64 cookie, int stack_size,
 			   int run_ctx_off, bool save_ret,
 			   void *image, void *rw_image)
 {
 	u8 *prog = *pprog;
 	u8 *jmp_insn;
 	int ctx_cookie_off = offsetof(struct bpf_tramp_run_ctx, bpf_cookie);
-	struct bpf_prog *p = l->link.prog;
-	u64 cookie = l->cookie;
 
 	/* mov rdi, cookie */
 	emit_mov_imm64(&prog, BPF_REG_1, (long) cookie >> 32, (u32) (long) cookie);
@@ -3079,7 +3077,8 @@ static int invoke_bpf(const struct btf_func_model *m, u8 **pprog,
 	u8 *prog = *pprog;
 
 	for (i = 0; i < tl->nr_links; i++) {
-		if (invoke_bpf_prog(m, &prog, tl->links[i], stack_size,
+		if (invoke_bpf_prog(m, &prog, bpf_tramp_links_prog(tl, i),
+				    tl->links[i]->cookie, stack_size,
 				    run_ctx_off, save_ret, image, rw_image))
 			return -EINVAL;
 	}
@@ -3101,8 +3100,9 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
 	emit_mov_imm32(&prog, false, BPF_REG_0, 0);
 	emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
 	for (i = 0; i < tl->nr_links; i++) {
-		if (invoke_bpf_prog(m, &prog, tl->links[i], stack_size, run_ctx_off, true,
-				    image, rw_image))
+		if (invoke_bpf_prog(m, &prog, bpf_tramp_links_prog(tl, i),
+				    tl->links[i]->cookie, stack_size,
+				    run_ctx_off, true, image, rw_image))
 			return -EINVAL;
 
 		/* mod_ret prog stored return value into [rbp - 8]. Emit:
@@ -3486,6 +3486,11 @@ int arch_protect_bpf_trampoline(void *image, unsigned int size)
 	return 0;
 }
 
+bool bpf_trampoline_supports_update_prog(void)
+{
+	return true;
+}
+
 int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end,
 				const struct btf_func_model *m, u32 flags,
 				struct bpf_tramp_links *tlinks,
-- 
2.43.0