Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Alexei Starovoitov says:

====================
pull-request: bpf-next 2020-09-23

The following pull-request contains BPF updates for your *net-next* tree.

We've added 95 non-merge commits during the last 22 day(s) which contain
a total of 124 files changed, 4211 insertions(+), 2040 deletions(-).

The main changes are:

1) Full multi function support in libbpf, from Andrii.

2) Refactoring of function argument checks, from Lorenz.

3) Make bpf_tail_call compatible with functions (subprograms), from Maciej.

4) Program metadata support, from YiFei.

5) bpf iterator optimizations, from Yonghong.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 42 insertions, 13 deletions

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index e046fb7d17cd..e5fd31268ae0 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -898,6 +898,7 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key,
 				    struct bpf_prog *old,
 				    struct bpf_prog *new)
 {
+	u8 *old_addr, *new_addr, *old_bypass_addr;
 	struct prog_poke_elem *elem;
 	struct bpf_array_aux *aux;
 
@@ -918,12 +919,13 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key,
 			 *    there could be danger of use after free otherwise.
 			 * 2) Initially when we start tracking aux, the program
 			 *    is not JITed yet and also does not have a kallsyms
-			 *    entry. We skip these as poke->ip_stable is not
-			 *    active yet. The JIT will do the final fixup before
-			 *    setting it stable. The various poke->ip_stable are
-			 *    successively activated, so tail call updates can
-			 *    arrive from here while JIT is still finishing its
-			 *    final fixup for non-activated poke entries.
+			 *    entry. We skip these as poke->tailcall_target_stable
+			 *    is not active yet. The JIT will do the final fixup
+			 *    before setting it stable. The various
+			 *    poke->tailcall_target_stable are successively
+			 *    activated, so tail call updates can arrive from here
+			 *    while JIT is still finishing its final fixup for
+			 *    non-activated poke entries.
 			 * 3) On program teardown, the program's kallsym entry gets
 			 *    removed out of RCU callback, but we can only untrack
 			 *    from sleepable context, therefore bpf_arch_text_poke()
@@ -940,7 +942,7 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key,
 			 * 5) Any other error happening below from bpf_arch_text_poke()
 			 *    is a unexpected bug.
 			 */
-			if (!READ_ONCE(poke->ip_stable))
+			if (!READ_ONCE(poke->tailcall_target_stable))
 				continue;
 			if (poke->reason != BPF_POKE_REASON_TAIL_CALL)
 				continue;
@@ -948,12 +950,39 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key,
 			    poke->tail_call.key != key)
 				continue;
 
-			ret = bpf_arch_text_poke(poke->ip, BPF_MOD_JUMP,
-						 old ? (u8 *)old->bpf_func +
-						 poke->adj_off : NULL,
-						 new ? (u8 *)new->bpf_func +
-						 poke->adj_off : NULL);
-			BUG_ON(ret < 0 && ret != -EINVAL);
+			old_bypass_addr = old ? NULL : poke->bypass_addr;
+			old_addr = old ? (u8 *)old->bpf_func + poke->adj_off : NULL;
+			new_addr = new ? (u8 *)new->bpf_func + poke->adj_off : NULL;
+
+			if (new) {
+				ret = bpf_arch_text_poke(poke->tailcall_target,
+							 BPF_MOD_JUMP,
+							 old_addr, new_addr);
+				BUG_ON(ret < 0 && ret != -EINVAL);
+				if (!old) {
+					ret = bpf_arch_text_poke(poke->tailcall_bypass,
+								 BPF_MOD_JUMP,
+								 poke->bypass_addr,
+								 NULL);
+					BUG_ON(ret < 0 && ret != -EINVAL);
+				}
+			} else {
+				ret = bpf_arch_text_poke(poke->tailcall_bypass,
+							 BPF_MOD_JUMP,
+							 old_bypass_addr,
+							 poke->bypass_addr);
+				BUG_ON(ret < 0 && ret != -EINVAL);
+				/* let other CPUs finish the execution of program
+				 * so that it will not possible to expose them
+				 * to invalid nop, stack unwind, nop state
+				 */
+				if (!ret)
+					synchronize_rcu();
+				ret = bpf_arch_text_poke(poke->tailcall_target,
+							 BPF_MOD_JUMP,
+							 old_addr, NULL);
+				BUG_ON(ret < 0 && ret != -EINVAL);
+			}
 		}
 	}
 }