Commit-ID: 952a6c2c094f4eda295f20c42e6e2d73735950fa
Gitweb: http://git.kernel.org/tip/952a6c2c094f4eda295f20c42e6e2d73735950fa
Author: Borislav Petkov <bp@xxxxxxx>
AuthorDate: Thu, 30 Mar 2017 09:44:05 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 31 Mar 2017 08:08:31 +0200
x86/boot/32: Flip the logic in test_wp_bit()
... to have a natural "likely()" in the code flow and thus have the
success case with a branch 99.999% of the times non-taken and function
return code following it instead of jumping to it each time.
This puts the panic() call at the end of the function - it is going to
be practically unreachable anyway.
The C code is a bit more readable too.
No functionality change.
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: boris.ostrovsky@xxxxxxxxxx
Cc: jgross@xxxxxxxx
Cc: thgarnie@xxxxxxxxxx
Link: http://lkml.kernel.org/r/20170330080101.ywsf5rg6ilzu4itk@xxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/mm/init_32.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 097089a..601b8e0 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -726,19 +726,18 @@ static void __init test_wp_bit(void)
{
char z = 0;
- printk(KERN_INFO
- "Checking if this processor honours the WP bit even in supervisor mode...");
+ printk(KERN_INFO "Checking if this processor honours the WP bit even in supervisor mode...");
__set_fixmap(FIX_WP_TEST, __pa_symbol(empty_zero_page), PAGE_KERNEL_RO);
- if (probe_kernel_write((char *)fix_to_virt(FIX_WP_TEST), &z, 1) == 0) {
- printk(KERN_CONT "No.\n");
- panic("Linux doesn't support CPUs with broken WP.");
+ if (probe_kernel_write((char *)fix_to_virt(FIX_WP_TEST), &z, 1)) {
+ clear_fixmap(FIX_WP_TEST);
+ printk(KERN_CONT "Ok.\n");
+ return;
}
- clear_fixmap(FIX_WP_TEST);
-
- printk(KERN_CONT "Ok.\n");
+ printk(KERN_CONT "No.\n");
+ panic("Linux doesn't support CPUs with broken WP.");
}
void __init mem_init(void)
--
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