diff options
| author | Jan Beulich <JBeulich@suse.com> | 2018-07-02 04:31:54 -0600 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-07-03 09:59:29 +0200 |
| commit | a7bea8308933aaeea76dad7d42a6e51000417626 (patch) | |
| tree | 66116addaa65ed59f9b8685911571fdeeb7df6f5 /arch/x86/kernel | |
| parent | c5fcdbf15523f6bbbaeb822e3be6003e60f9d3b7 (diff) | |
| download | linux-a7bea8308933aaeea76dad7d42a6e51000417626.tar.bz2 | |
x86/asm/64: Use 32-bit XOR to zero registers
Some Intel CPUs don't recognize 64-bit XORs as zeroing idioms. Zeroing
idioms don't require execution bandwidth, as they're being taken care
of in the frontend (through register renaming). Use 32-bit XORs instead.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: herbert@gondor.apana.org.au
Cc: pavel@ucw.cz
Cc: rjw@rjwysocki.net
Link: http://lkml.kernel.org/r/5B39FF1A02000078001CFB54@prv1-mh.provo.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/head_64.S | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/paravirt_patch_64.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 8344dd2f310a..15ebc2fc166e 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -235,7 +235,7 @@ ENTRY(secondary_startup_64) * address given in m16:64. */ pushq $.Lafter_lret # put return address on stack for unwinder - xorq %rbp, %rbp # clear frame pointer + xorl %ebp, %ebp # clear frame pointer movq initial_code(%rip), %rax pushq $__KERNEL_CS # set correct cs pushq %rax # target address in negative space diff --git a/arch/x86/kernel/paravirt_patch_64.c b/arch/x86/kernel/paravirt_patch_64.c index 9edadabf04f6..9cb98f7b07c9 100644 --- a/arch/x86/kernel/paravirt_patch_64.c +++ b/arch/x86/kernel/paravirt_patch_64.c @@ -20,7 +20,7 @@ DEF_NATIVE(, mov64, "mov %rdi, %rax"); #if defined(CONFIG_PARAVIRT_SPINLOCKS) DEF_NATIVE(pv_lock_ops, queued_spin_unlock, "movb $0, (%rdi)"); -DEF_NATIVE(pv_lock_ops, vcpu_is_preempted, "xor %rax, %rax"); +DEF_NATIVE(pv_lock_ops, vcpu_is_preempted, "xor %eax, %eax"); #endif unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len) |