* Kirill A. Shutemov kirill.shutemov@linux.intel.com wrote:
0-day reported this build error:
arch/x86/boot/compressed/pgtable_64.o: In function `l5_paging_required': pgtable_64.c:(.text+0x22): undefined reference to `__force_order'
The issue is only with GCC < 5 and when KASLR is disabled. Newer GCC works fine.
__force_order is used by special_insns.h asm code to force instruction serialization.
s/is used by special_insns.h asm code /is used by the special_insns.h asm code
It doesn't actually referenced from the code, but GCC < 5 with -fPIE would still generate undefined symbol.
s/It doesn't actually referenced from the code /It isn't actually referenced from the code
s/would still generate undefined symbol. /would still generate an undefined symbol.
I didn't noticed this before and failed to move __force_order definition from pagetable.c (which compiles only with KASLR enabled) to pgtable_64.c.
Signed-off-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Fixes: 10c9a5346f72 ("x86/boot/compressed/64: Detect and handle 5-level paging at boot-time") Cc: stable@vger.kernel.org
arch/x86/boot/compressed/pagetable.c | 3 --- arch/x86/boot/compressed/pgtable_64.c | 11 +++++++++++ 2 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/arch/x86/boot/compressed/pagetable.c b/arch/x86/boot/compressed/pagetable.c index 6bd51de4475c..250826ac216e 100644 --- a/arch/x86/boot/compressed/pagetable.c +++ b/arch/x86/boot/compressed/pagetable.c @@ -38,9 +38,6 @@ #define __PAGE_OFFSET __PAGE_OFFSET_BASE #include "../../mm/ident_map.c" -/* Used by pgtable.h asm code to force instruction serialization. */ -unsigned long __force_order;
/* Used to track our page table allocation area. */ struct alloc_pgt_data { unsigned char *pgt_buf; diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c index 7bcf03b376da..491fa2d08bca 100644 --- a/arch/x86/boot/compressed/pgtable_64.c +++ b/arch/x86/boot/compressed/pgtable_64.c @@ -1,5 +1,16 @@ #include <asm/processor.h> +/*
- __force_order is used by special_insns.h asm code to force instruction
- serialization.
s/is used by special_insns.h asm code /is used by the special_insns.h asm code
- It doesn't actually referenced from the code, but GCC < 5 with -fPIE
- would still generate undefined symbol.
s/It doesn't actually referenced from the code /It isn't actually referenced from the code
s/would still generate undefined symbol. /would still generate an undefined symbol.
- Let's workaround this by defining the variable.
s/Let's workaround /Let's work around
Also, for the title:
s/Fix build with GCC < 5 /Fix the build with GCC < 5
Thanks,
Ingo