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Subject[PATCH] x86/head_64.S: do not use temporary register to check alignment
Date
We are using temporary %rax register during checking of kernel address
alignment. We can ged rid of it since testl instruction is safe and does
not change value of the rbp register.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Suggested-by: Brian Gerst <brgerst@gmail.com>
---
arch/x86/kernel/head_64.S | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index ffdc0e8..7c21029 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -76,9 +76,7 @@ startup_64:
subq $_text - __START_KERNEL_map, %rbp

/* Is the address not 2M aligned? */
- movq %rbp, %rax
- andl $~PMD_PAGE_MASK, %eax
- testl %eax, %eax
+ testl $~PMD_PAGE_MASK, %ebp
jnz bad_address

/*
--
2.7.0.25.gfc10eb5
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