Messages in this thread | | | Date | Thu, 7 Dec 2017 07:16:24 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCHv4 1/4] x86/boot/compressed/64: Fix build with GCC < 5 |
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* 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
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