linux-kernel - [patch V4 part 4 04/24] x86/int3: Inline bsearch()

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Date:   Tue, 05 May 2020 15:49:30 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, "Paul E. McKenney" <paulmck@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Brian Gerst <brgerst@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Will Deacon <will@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: [patch V4 part 4 04/24] x86/int3: Inline bsearch()

From: Peter Zijlstra <peterz@...radead.org>

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

--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -979,7 +979,7 @@ static __always_inline void *text_poke_a
 	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_
 	 * 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 = __bsearch(ip, desc->vec, desc->nr_entries,
+			       sizeof(struct text_poke_loc),
+			       patch_cmp);
 		if (!tp)
 			goto out_put;
 	} else {
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -566,6 +566,11 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_pr
 
 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;