Merge branch 'kprobes: rethook: x86: Replace kretprobe trampoline with rethook'

Masami Hiramatsu says:

====================
Here are the 3rd version for generic kretprobe and kretprobe on x86 for
replacing the kretprobe trampoline with rethook. The previous version
is here[1]

[1] https://lore.kernel.org/all/164821817332.2373735.12048266953420821089.stgit@devnote2/T/#u

This version fixed typo and build issues for bpf-next and CONFIG_RETHOOK=y
error. I also add temporary mitigation lines for ANNOTATE_NOENDBR macro
issue for bpf-next tree [2/4].

This will be removed after merging kernel IBT series.

Background:

This rethook came from Jiri's request of multiple kprobe for bpf[2].
He tried to solve an issue that starting bpf with multiple kprobe will
take a long time because bpf-kprobe will wait for RCU grace period for
sync rcu events.

Jiri wanted to attach a single bpf handler to multiple kprobes and
he tried to introduce multiple-probe interface to kprobe. So I asked
him to use ftrace and kretprobe-like hook if it is only for the
function entry and exit, instead of adding ad-hoc interface
to kprobes.
For this purpose, I introduced the fprobe (kprobe like interface for
ftrace) with the rethook (this is a generic return hook feature for
fprobe exit handler)[3].

[2] https://lore.kernel.org/all/[email protected]/T/#u
[3] https://lore.kernel.org/all/164191321766.806991.7930388561276940676.stgit@devnote2/T/#u

The rethook is basically same as the kretprobe trampoline. I just made
it decoupled from kprobes. Eventually, the all arch dependent kretprobe
trampolines will be replaced with the rethook trampoline instead of
cloning and set HAVE_RETHOOK=y.
When I port the rethook for all arch which supports kretprobe, the
legacy kretprobe specific code (which is for CONFIG_KRETPROBE_ON_RETHOOK=n)
will be removed eventually.
====================

Acked-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>

1 files changed, 11 insertions, 12 deletions

diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h
index 2a1f8734416d..7cede4dc21f0 100644
--- a/arch/x86/include/asm/unwind.h
+++ b/arch/x86/include/asm/unwind.h
@@ -4,7 +4,7 @@
 
 #include <linux/sched.h>
 #include <linux/ftrace.h>
-#include <linux/kprobes.h>
+#include <linux/rethook.h>
 #include <asm/ptrace.h>
 #include <asm/stacktrace.h>
 
@@ -16,7 +16,7 @@ struct unwind_state {
 	unsigned long stack_mask;
 	struct task_struct *task;
 	int graph_idx;
-#ifdef CONFIG_KRETPROBES
+#if defined(CONFIG_RETHOOK)
 	struct llist_node *kr_cur;
 #endif
 	bool error;
@@ -104,19 +104,18 @@ void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
 #endif
 
 static inline
-unsigned long unwind_recover_kretprobe(struct unwind_state *state,
-				       unsigned long addr, unsigned long *addr_p)
+unsigned long unwind_recover_rethook(struct unwind_state *state,
+				     unsigned long addr, unsigned long *addr_p)
 {
-#ifdef CONFIG_KRETPROBES
-	return is_kretprobe_trampoline(addr) ?
-		kretprobe_find_ret_addr(state->task, addr_p, &state->kr_cur) :
-		addr;
-#else
-	return addr;
+#ifdef CONFIG_RETHOOK
+	if (is_rethook_trampoline(addr))
+		return rethook_find_ret_addr(state->task, (unsigned long)addr_p,
+					     &state->kr_cur);
 #endif
+	return addr;
 }
 
-/* Recover the return address modified by kretprobe and ftrace_graph. */
+/* Recover the return address modified by rethook and ftrace_graph. */
 static inline
 unsigned long unwind_recover_ret_addr(struct unwind_state *state,
 				     unsigned long addr, unsigned long *addr_p)
@@ -125,7 +124,7 @@ unsigned long unwind_recover_ret_addr(struct unwind_state *state,
 
 	ret = ftrace_graph_ret_addr(state->task, &state->graph_idx,
 				    addr, addr_p);
-	return unwind_recover_kretprobe(state, ret, addr_p);
+	return unwind_recover_rethook(state, ret, addr_p);
 }
 
 /*