Commit-ID: 952a6c2c094f4eda295f20c42e6e2d73735950fa Gitweb: http://git.kernel.org/tip/952a6c2c094f4eda295f20c42e6e2d73735950fa Author: Borislav Petkov <[email protected]> AuthorDate: Thu, 30 Mar 2017 09:44:05 +0200 Committer: Ingo Molnar <[email protected]> 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 <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- 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)
