[PATCH 4.19] Revert "x86/speculation: Change FILL_RETURN_BUFFER to work with objtool"

[PATCH 4.19] Revert "x86/speculation: Change FILL_RETURN_BUFFER to work with objtool"

[Ben Hutchings]

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This reverts commit 9f3330d4930e034d84ee6561fbfb098433ff0ab9, which
was commit 089dd8e53126ebaf506e2dc0bf89d652c36bfc12 upstream.

The necessary changes to objtool have not been backported to 4.19.
Backporting this commit alone only added build warnings.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 arch/x86/include/asm/nospec-branch.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 64b086c47b4a..0f99dda233a5 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -4,13 +4,11 @@
 #define _ASM_X86_NOSPEC_BRANCH_H_
 
 #include <linux/static_key.h>
-#include <linux/frame.h>
 
 #include <asm/alternative.h>
 #include <asm/alternative-asm.h>
 #include <asm/cpufeatures.h>
 #include <asm/msr-index.h>
-#include <asm/unwind_hints.h>
 #include <asm/percpu.h>
 
 /*
@@ -54,9 +52,9 @@
 	lfence;					\
 	jmp	775b;				\
 774:						\
-	add	$(BITS_PER_LONG/8) * 2, sp;	\
 	dec	reg;				\
 	jnz	771b;				\
+	add	$(BITS_PER_LONG/8) * nr, sp;	\
 	/* barrier for jnz misprediction */	\
 	lfence;
 #else
@@ -167,8 +165,10 @@
   * monstrosity above, manually.
   */
 .macro FILL_RETURN_BUFFER reg:req nr:req ftr:req
-	ALTERNATIVE "jmp .Lskip_rsb_\@", "", \ftr
-	__FILL_RETURN_BUFFER(\reg,\nr,%_ASM_SP)
+	ANNOTATE_NOSPEC_ALTERNATIVE
+	ALTERNATIVE "jmp .Lskip_rsb_\@",				\
+		__stringify(__FILL_RETURN_BUFFER(\reg,\nr,%_ASM_SP))	\
+		\ftr
 .Lskip_rsb_\@:
 .endm
 

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Re: [PATCH 4.19] Revert "x86/speculation: Change FILL_RETURN_BUFFER to work with objtool"

[Greg KH]

On Mon, Dec 05, 2022 at 10:31:24PM +0100, Ben Hutchings wrote:
> This reverts commit 9f3330d4930e034d84ee6561fbfb098433ff0ab9, which
> was commit 089dd8e53126ebaf506e2dc0bf89d652c36bfc12 upstream.
> 
> The necessary changes to objtool have not been backported to 4.19.
> Backporting this commit alone only added build warnings.
> 
> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
> ---
>  arch/x86/include/asm/nospec-branch.h | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)

Now queued up, thanks.

greg k-h