linux-kernel - [tip: x86/entry] x86/int3: Inline bsearch()

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Message-ID: <158991830602.17951.12536821742212789532.tip-bot2@tip-bot2>
Date:   Tue, 19 May 2020 19:58:26 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Andy Lutomirski <luto@...nel.org>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: x86/entry] x86/int3: Inline bsearch()

The following commit has been merged into the x86/entry branch of tip:

Commit-ID:     c3be358894063fc2a628dd94ca7f17c232177dbb
Gitweb:        https://git.kernel.org/tip/c3be358894063fc2a628dd94ca7f17c232177dbb
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Thu, 20 Feb 2020 13:28:06 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Tue, 19 May 2020 16:04:05 +02:00

x86/int3: Inline bsearch()

Avoid calling out to bsearch() by inlining it, for normal kernel configs
this was the last external call and poke_int3_handler() is now fully self
sufficient -- no calls to external code.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@...cle.com>
Acked-by: Andy Lutomirski <luto@...nel.org>
Link: https://lkml.kernel.org/r/20200505135313.731774429@linutronix.de


---
 arch/x86/kernel/alternative.c | 8 ++++----
 arch/x86/kernel/traps.c       | 5 +++++
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 686c8ac..0f70712 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -979,7 +979,7 @@ static __always_inline void *text_poke_addr(struct text_poke_loc *tp)
 	return _stext + tp->rel_addr;
 }
 
-static int noinstr patch_cmp(const void *key, const void *elt)
+static __always_inline int patch_cmp(const void *key, const void *elt)
 {
 	struct text_poke_loc *tp = (struct text_poke_loc *) elt;
 
@@ -1023,9 +1023,9 @@ int noinstr poke_int3_handler(struct pt_regs *regs)
 	 * Skip the binary search if there is a single member in the vector.
 	 */
 	if (unlikely(desc->nr_entries > 1)) {
-		tp = bsearch(ip, desc->vec, desc->nr_entries,
-			     sizeof(struct text_poke_loc),
-			     patch_cmp);
+		tp = __inline_bsearch(ip, desc->vec, desc->nr_entries,
+				      sizeof(struct text_poke_loc),
+				      patch_cmp);
 		if (!tp)
 			goto out_put;
 	} else {
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index b28a64d..280c290 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -570,6 +570,11 @@ exit:
 
 dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
 {
+	/*
+	 * poke_int3_handler() is completely self contained code; it does (and
+	 * must) *NOT* call out to anything, lest it hits upon yet another
+	 * INT3.
+	 */
 	if (poke_int3_handler(regs))
 		return;