If kernel doesn't use kASLR and runned on the same address that was
compiled to run, %rbp will be zero and no need to fix physical addresses
in the page tables.
Signed-off-by: Alexander Kuleshov <kuleshovm...@gmail.com>
---
arch/x86/kernel/head_64.S | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 6fd514d9..c0127bc 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -86,6 +86,14 @@ startup_64:
jnz bad_address
/*
+ * We have no need to fixup the physical addresses in the page tables
+ * if there is no difference between the address where kernel compiled
+ * to run and the actual address where kernel running at.
+ */
+ cmpq $0x0, %rbp
+ je 1f
+
+ /*
* Fixup the physical addresses in the page table
*/
addq %rbp, early_level4_pgt + (L4_START_KERNEL*8)(%rip)
@@ -95,6 +103,7 @@ startup_64:
addq %rbp, level2_fixmap_pgt + (506*8)(%rip)
+1:
/*
* Set up the identity mapping for the switchover. These
* entries should *NOT* have the global bit set! This also
--
2.3.1.167.g7f4ba4b
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