diff mbox series

[v3,2/5] powerpc: module_[32|64].c: replace swap function with built-in one

Message ID 994931554238042@iva8-b333b7f98ab0.qloud-c.yandex.net (mailing list archive)
State Accepted
Commit bac7ca7b985b72873bd4ac2553b13b5af5b1f08a
Headers show
Series simple sort swap function improvements | expand

Checks

Context Check Description
snowpatch_ozlabs/apply_patch success Successfully applied on branch next (8c2ffd9174779014c3fe1f96d9dc3641d9175f00)
snowpatch_ozlabs/checkpatch warning total: 0 errors, 0 warnings, 2 checks, 58 lines checked

Commit Message

Andrey Abramov April 2, 2019, 8:47 p.m. UTC 
Replace relaswap with built-in one, because relaswap
does a simple byte to byte swap.

Since Spectre mitigations have made indirect function calls more
expensive, and the default simple byte copies swap is implemented
without them, an "optimized" custom swap function is now
a waste of time as well as code.

Signed-off-by: Andrey Abramov <st5pub@yandex.ru>
Reviewed by: George Spelvin <lkml@sdf.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
---
v2->v3: nothing changed

 arch/powerpc/kernel/module_32.c | 17 +----------------
 arch/powerpc/kernel/module_64.c | 17 +----------------
 2 files changed, 2 insertions(+), 32 deletions(-)

Comments

Michael Ellerman June 9, 2020, 5:58 a.m. UTC | #1 
On Tue, 2019-04-02 at 20:47:22 UTC, Andrey Abramov wrote:
> Replace relaswap with built-in one, because relaswap
> does a simple byte to byte swap.
> 
> Since Spectre mitigations have made indirect function calls more
> expensive, and the default simple byte copies swap is implemented
> without them, an "optimized" custom swap function is now
> a waste of time as well as code.
> 
> Signed-off-by: Andrey Abramov <st5pub@yandex.ru>
> Reviewed by: George Spelvin <lkml@sdf.org>
> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/bac7ca7b985b72873bd4ac2553b13b5af5b1f08a

cheers
diff mbox series

Patch

diff --git a/arch/powerpc/kernel/module_32.c b/arch/powerpc/kernel/module_32.c
index 88d83771f462..c311e8575d10 100644
--- a/arch/powerpc/kernel/module_32.c
+++ b/arch/powerpc/kernel/module_32.c
@@ -79,21 +79,6 @@  static int relacmp(const void *_x, const void *_y)
 		return 0;
 }
 
-static void relaswap(void *_x, void *_y, int size)
-{
-	uint32_t *x, *y, tmp;
-	int i;
-
-	y = (uint32_t *)_x;
-	x = (uint32_t *)_y;
-
-	for (i = 0; i < sizeof(Elf32_Rela) / sizeof(uint32_t); i++) {
-		tmp = x[i];
-		x[i] = y[i];
-		y[i] = tmp;
-	}
-}
-
 /* Get the potential trampolines size required of the init and
    non-init sections */
 static unsigned long get_plt_size(const Elf32_Ehdr *hdr,
@@ -130,7 +115,7 @@  static unsigned long get_plt_size(const Elf32_Ehdr *hdr,
 			 */
 			sort((void *)hdr + sechdrs[i].sh_offset,
 			     sechdrs[i].sh_size / sizeof(Elf32_Rela),
-			     sizeof(Elf32_Rela), relacmp, relaswap);
+			     sizeof(Elf32_Rela), relacmp, NULL);
 
 			ret += count_relocs((void *)hdr
 					     + sechdrs[i].sh_offset,
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index 8661eea78503..0c833d7f36f1 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -231,21 +231,6 @@  static int relacmp(const void *_x, const void *_y)
 		return 0;
 }
 
-static void relaswap(void *_x, void *_y, int size)
-{
-	uint64_t *x, *y, tmp;
-	int i;
-
-	y = (uint64_t *)_x;
-	x = (uint64_t *)_y;
-
-	for (i = 0; i < sizeof(Elf64_Rela) / sizeof(uint64_t); i++) {
-		tmp = x[i];
-		x[i] = y[i];
-		y[i] = tmp;
-	}
-}
-
 /* Get size of potential trampolines required. */
 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
 				    const Elf64_Shdr *sechdrs)
@@ -269,7 +254,7 @@  static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
 			 */
 			sort((void *)sechdrs[i].sh_addr,
 			     sechdrs[i].sh_size / sizeof(Elf64_Rela),
-			     sizeof(Elf64_Rela), relacmp, relaswap);
+			     sizeof(Elf64_Rela), relacmp, NULL);
 
 			relocs += count_relocs((void *)sechdrs[i].sh_addr,
 					       sechdrs[i].sh_size