xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Revert "x86/retpoline: Simplify vmexit_fill_RSB()"

Browse Source 
This reverts commit 1dde7415e9. By putting
the RSB filling out of line and calling it, we waste one RSB slot for
returning from the function itself, which means one fewer actual function
call we can make if we're doing the Skylake abomination of call-depth
counting.

It also changed the number of RSB stuffings we do on vmexit from 32,
which was correct, to 16. Let's just stop with the bikeshedding; it
didn't actually *fix* anything anyway.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: arjan.van.de.ven@intel.com
Cc: bp@alien8.de
Cc: dave.hansen@intel.com
Cc: jmattson@google.com
Cc: karahmed@amazon.de
Cc: kvm@vger.kernel.org
Cc: pbonzini@redhat.com
Cc: rkrcmar@redhat.com
Link: http://lkml.kernel.org/r/1519037457-7643-4-git-send-email-dwmw@amazon.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
David Woodhouse
2018-02-19 10:50:56 +00:00
committed by Ingo Molnar
parent 8554004a02
commit d1c99108af
6 changed files with 65 additions and 71 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/entry/entry_32.S
View File

@@ -252,8 +252,7 @@ ENTRY(__switch_to_asm)
* exist, overwrite the RSB with entries which capture
* speculative execution to prevent attack.
*/
/* Clobbers %ebx */
FILL_RETURN_BUFFER RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW
FILL_RETURN_BUFFER %ebx, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW
#endif
/* restore callee-saved registers */

3
arch/x86/entry/entry_64.S
View File

@@ -364,8 +364,7 @@ ENTRY(__switch_to_asm)
* exist, overwrite the RSB with entries which capture
* speculative execution to prevent attack.
*/
/* Clobbers %rbx */
FILL_RETURN_BUFFER RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW
FILL_RETURN_BUFFER %r12, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW
#endif
/* restore callee-saved registers */