[PATCH v2 1/4] x86/mm: surround level4_kernel_pgt with #ifdef CONFIG_X86_5LEVEL...#endif
From: Masahiro Yamada <hidden>
Date: 2018-10-28 01:45:29
Also in:
linux-kbuild, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
On Fri, Oct 19, 2018 at 9:50 PM Du Changbin [off-list ref] wrote:
The level4_kernel_pgt is only defined when X86_5LEVEL is enabled. So surround level4_kernel_pgt with #ifdef CONFIG_X86_5LEVEL...#endif to make code correct.
For clarification, is it better to mention that this is a preparation for CONFIG_CC_OPTIMIZE_FOR_DEBUGGING ?
quoted hunk ↗ jump to hunk
Signed-off-by: Du Changbin <redacted> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> --- arch/x86/include/asm/pgtable_64.h | 2 ++ arch/x86/kernel/head64.c | 13 ++++++------- 2 files changed, 8 insertions(+), 7 deletions(-)diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h index 9c85b54bf03c..9333f7fa5bdb 100644 --- a/arch/x86/include/asm/pgtable_64.h +++ b/arch/x86/include/asm/pgtable_64.h@@ -16,7 +16,9 @@ #include <linux/threads.h> #include <asm/fixmap.h> +#ifdef CONFIG_X86_5LEVEL extern p4d_t level4_kernel_pgt[512]; +#endif
Is this #ifdef necessary? It is harmless to declaring unused stuff.
quoted hunk ↗ jump to hunk
extern p4d_t level4_ident_pgt[512]; extern pud_t level3_kernel_pgt[512]; extern pud_t level3_ident_pgt[512];diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index ddee1f0870c4..4a59ef93c258 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c@@ -151,16 +151,15 @@ unsigned long __head __startup_64(unsigned long physaddr, pgd = fixup_pointer(&early_top_pgt, physaddr); p = pgd + pgd_index(__START_KERNEL_map); - if (la57) - *p = (unsigned long)level4_kernel_pgt; - else - *p = (unsigned long)level3_kernel_pgt; - *p += _PAGE_TABLE_NOENC - __START_KERNEL_map + load_delta; - +#ifdef CONFIG_X86_5LEVEL if (la57) { + *p = (unsigned long)level4_kernel_pgt; p4d = fixup_pointer(&level4_kernel_pgt, physaddr); p4d[511] += load_delta; - } + } else +#endif + *p = (unsigned long)level3_kernel_pgt; + *p += _PAGE_TABLE_NOENC - __START_KERNEL_map + load_delta; pud = fixup_pointer(&level3_kernel_pgt, physaddr); pud[510] += load_delta; --2.17.1
Hmm, this code looks a bit ugly... Does the following one liner work with CONFIG_CC_OPTIMIZE_FOR_DEBUGGING ?
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 8047379..579847f 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c@@ -97,7 +97,7 @@ static bool __head check_la57_support(unsigned long physaddr) return true; } #else -static bool __head check_la57_support(unsigned long physaddr) +static __always_inline bool __head check_la57_support(unsigned long physaddr) { return false; } --
Best Regards Masahiro Yamada