[PATCH] x86/head/64: level2_kernel_pgt's kernel area is built with _PAGE_PRESENT set

Wei Yang
2024-03-23T23:26:26Z

The code is first introduced in 'commit 1ab60e0f72f7 ("[PATCH] x86-64:
Relocatable Kernel Support")'. Then 'commit c88d71508e36b
("x86/boot/64: Rewrite startup_64() in C")', convert it to c. And
'commit 2aa85f246c181 ("x86/boot/64: Make level2_kernel_pgt pages
invalid outside kernel area")' limit the range from _text to _end.

Originally, it does the check because the loop iterate the whole
level2_kernel_pgt, while currently it just fixup the kernel area. This
area is built with _PAGE_PRESENT set.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
CC: Vivek Goyal <vgoyal@in.ibm.com>
CC: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
CC: Ingo Molnar <mingo@kernel.org>
CC: Steve Wahl <steve.wahl@hpe.com>
CC: Borislav Petkov <bp@suse.de>
---
arch/x86/kernel/head64.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 212e8e06aeba..75c69f8620d8 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -253,8 +253,7 @@ unsigned long __head __startup_64(unsigned long physaddr,

/* fixup pages that are part of the kernel image */
for (; i <= pmd_index((unsigned long)_end); i++)
- if (pmd[i] & _PAGE_PRESENT)
- pmd[i] += load_delta;
+ pmd[i] += load_delta;

/* invalidate pages after the kernel image */
for (; i < PTRS_PER_PMD; i++)
--
2.34.1