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From:   Masami Hiramatsu <mhiramat@kernel.org>
To:     Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@kernel.org>
Cc:     X86 ML <x86@kernel.org>, Masami Hiramatsu <mhiramat@kernel.org>,
        Daniel Xu <dxu@dxuuu.xyz>, linux-kernel@vger.kernel.org,
        bpf@vger.kernel.org, kuba@kernel.org, mingo@redhat.com,
        ast@kernel.org, tglx@linutronix.de, kernel-team@fb.com, yhs@fb.com,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        linux-ia64@vger.kernel.org,
        Abhishek Sagar <sagar.abhishek@gmail.com>,
        Andrii Nakryiko <andrii.nakryiko@gmail.com>
Subject: [PATCH -tip v6 01/13] ia64: kprobes: Fix to pass correct trampoline address to the handler
Date:   Wed, 26 May 2021 17:02:20 +0900
Message-Id: <162201614019.278331.4298879353454259298.stgit@devnote2>
In-Reply-To: <162201612941.278331.5293566981784464165.stgit@devnote2>
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Commit e792ff804f49 ("ia64: kprobes: Use generic kretprobe trampoline handler")
missed to pass the wrong trampoline address (it passes the descriptor address
instead of function entry address).
This fixes it to pass correct trampoline address to __kretprobe_trampoline_handler().
This also changes to use correct symbol dereference function to get the
function address from the kretprobe_trampoline.

Fixes: e792ff804f49 ("ia64: kprobes: Use generic kretprobe trampoline handler")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 Changes in v5:
  - Fix a compile error typo.
---
 arch/ia64/kernel/kprobes.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index fc1ff8a4d7de..ca4b4fa45aef 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -398,7 +398,8 @@ static void kretprobe_trampoline(void)
 
 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 {
-	regs->cr_iip = __kretprobe_trampoline_handler(regs, kretprobe_trampoline, NULL);
+	regs->cr_iip = __kretprobe_trampoline_handler(regs,
+		dereference_function_descriptor(kretprobe_trampoline), NULL);
 	/*
 	 * By returning a non-zero value, we are telling
 	 * kprobe_handler() that we don't want the post_handler
@@ -414,7 +415,7 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
 	ri->fp = NULL;
 
 	/* Replace the return addr with trampoline addr */
-	regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
+	regs->b0 = (unsigned long)dereference_function_descriptor(kretprobe_trampoline);
 }
 
 /* Check the instruction in the slot is break */
@@ -918,14 +919,14 @@ static struct kprobe trampoline_p = {
 int __init arch_init_kprobes(void)
 {
 	trampoline_p.addr =
-		(kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
+		dereference_function_descriptor(kretprobe_trampoline);
 	return register_kprobe(&trampoline_p);
 }
 
 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 {
 	if (p->addr ==
-		(kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip)
+		dereference_function_descriptor(kretprobe_trampoline))
 		return 1;
 
 	return 0;