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

From: Thomas Gleixner
Date: Tue May 05 2020 - 10:20:00 EST


From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

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@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
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;