From ff3ce03865a033794db368170f82023850164c81 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: May 08 2023 13:20:13 +0000
Subject: x86: don't use REP_GOOD or ERMS for small memory clearing

(bsc#1211140).

---

diff --git a/patches.suse/x86-don-t-use-REP_GOOD-or-ERMS-for-small-memory-clea.patch b/patches.suse/x86-don-t-use-REP_GOOD-or-ERMS-for-small-memory-clea.patch
new file mode 100644
index 0000000..ca20686
--- /dev/null
+++ b/patches.suse/x86-don-t-use-REP_GOOD-or-ERMS-for-small-memory-clea.patch
@@ -0,0 +1,88 @@
+From 20f3337d350c4e1b4ac66d731fd4e98565bf6cc0 Mon Sep 17 00:00:00 2001
+From: Linus Torvalds <torvalds@linux-foundation.org>
+Date: Sat, 15 Apr 2023 12:01:14 -0700
+Subject: [PATCH] x86: don't use REP_GOOD or ERMS for small memory clearing
+Git-commit: 20f3337d350c4e1b4ac66d731fd4e98565bf6cc0
+Patch-mainline: v6.4-rc1
+References: bsc#1211140
+
+The modern target to use is FSRS (Fast Short REP STOS), and the other
+cases should only be used for bigger areas (ie mainly things like page
+clearing).
+
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Acked-by: Takashi Iwai <tiwai@suse.de>
+
+---
+ arch/x86/lib/memset_64.S |   47 +++++++++++------------------------------------
+ 1 file changed, 11 insertions(+), 36 deletions(-)
+
+--- a/arch/x86/lib/memset_64.S
++++ b/arch/x86/lib/memset_64.S
+@@ -16,28 +16,23 @@
+  * rdx   count (bytes)
+  *
+  * rax   original destination
++ *
++ * The FSRS alternative should be done inline (avoiding the call and
++ * the disgusting return handling), but that would require some help
++ * from the compiler for better calling conventions.
++ *
++ * The 'rep stosb' itself is small enough to replace the call, but all
++ * the register moves blow up the code. And two of them are "needed"
++ * only for the return value that is the same as the source input,
++ * which the compiler could/should do much better anyway.
+  */
+ SYM_FUNC_START_WEAK(memset)
+ SYM_FUNC_START(__memset)
+-	/*
+-	 * Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended
+-	 * to use it when possible. If not available, use fast string instructions.
+-	 *
+-	 * Otherwise, use original memset function.
+-	 */
+-	ALTERNATIVE_2 "jmp memset_orig", "", X86_FEATURE_REP_GOOD, \
+-		      "jmp memset_erms", X86_FEATURE_ERMS
++	ALTERNATIVE "jmp memset_orig", "", X86_FEATURE_FSRS
+ 
+ 	movq %rdi,%r9
++	movb %sil,%al
+ 	movq %rdx,%rcx
+-	andl $7,%edx
+-	shrq $3,%rcx
+-	/* expand byte value  */
+-	movzbl %sil,%esi
+-	movabs $0x0101010101010101,%rax
+-	imulq %rsi,%rax
+-	rep stosq
+-	movl %edx,%ecx
+ 	rep stosb
+ 	movq %r9,%rax
+ 	RET
+@@ -46,26 +41,6 @@ SYM_FUNC_END_ALIAS(memset)
+ EXPORT_SYMBOL(memset)
+ EXPORT_SYMBOL(__memset)
+ 
+-/*
+- * ISO C memset - set a memory block to a byte value. This function uses
+- * enhanced rep stosb to override the fast string function.
+- * The code is simpler and shorter than the fast string function as well.
+- *
+- * rdi   destination
+- * rsi   value (char)
+- * rdx   count (bytes)
+- *
+- * rax   original destination
+- */
+-SYM_FUNC_START_LOCAL(memset_erms)
+-	movq %rdi,%r9
+-	movb %sil,%al
+-	movq %rdx,%rcx
+-	rep stosb
+-	movq %r9,%rax
+-	RET
+-SYM_FUNC_END(memset_erms)
+-
+ SYM_FUNC_START_LOCAL(memset_orig)
+ 	movq %rdi,%r10
+ 
diff --git a/series.conf b/series.conf
index cf377aa..69064b6 100644
--- a/series.conf
+++ b/series.conf
@@ -36928,6 +36928,7 @@
 	patches.suse/nfc-st-nci-Fix-use-after-free-bug-in-ndlc_remove-due.patch
 	patches.suse/s390-uaccess-add-missing-earlyclobber-annotations-to-__clear_user.patch
 	patches.suse/vmxnet3-use-gro-callback-when-UPT-is-enabled.patch
+	patches.suse/x86-don-t-use-REP_GOOD-or-ERMS-for-small-memory-clea.patch
 
 	########################################################
 	# end of sorted patches