[PATCH] x86: Page align _end to avoid pfn conversion bugs

From: Matt Fleming
Date: Fri Nov 20 2015 - 06:46:11 EST

Ingo noted that if we can guarantee _end is aligned to PAGE_SIZE we
can automatically avoid bugs along the lines of,

size = _end - _text >> PAGE_SHIFT

which is missing a call to PFN_ALIGN(). The EFI mixed mode contains
this bug, for example.

_text is already aligned to PAGE_SIZE through the use of
LOAD_PHYSICAL_ADDR, and the BSS and BRK sections are explicitly
aligned in the linker script, so it makes sense to align _end to

Reported-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H . Peter Anvin" <hpa@xxxxxxxxx>
Cc: Toshi Kani <toshi.kani@xxxxxx>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Signed-off-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
arch/x86/kernel/vmlinux.lds.S | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 74e4bf11f562..4f1994257a18 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -325,6 +325,7 @@ SECTIONS
__brk_limit = .;

_end = .;


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/