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x86/boot: Mark global variables as static

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Mike Lothian reports that after commit
  964124a97b ("efi/x86: Remove extra headroom for setup block")
gcc 10.1.0 fails with

  HOSTCC  arch/x86/boot/tools/build
  /usr/lib/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../x86_64-pc-linux-gnu/bin/ld:
  error: linker defined: multiple definition of '_end'
  /usr/lib/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../x86_64-pc-linux-gnu/bin/ld:
  /tmp/ccEkW0jM.o: previous definition here
  collect2: error: ld returned 1 exit status
  make[1]: *** [scripts/Makefile.host:103: arch/x86/boot/tools/build] Error 1
  make: *** [arch/x86/Makefile:303: bzImage] Error 2

The issue is with the _end variable that was added, to hold the end of
the compressed kernel from zoffsets.h (ZO__end). The name clashes with
the linker-defined _end symbol that indicates the end of the build
program itself.

Even when there is no compile-time error, this causes build to use
memory past the end of its .bss section.

To solve this, mark _end as static, and for symmetry, mark the rest of
the variables that keep track of symbols from the compressed kernel as
static as well.

Fixes: 964124a97b ("efi/x86: Remove extra headroom for setup block")
Reported-by: Mike Lothian <mike@fireburn.co.uk>
Tested-by: Mike Lothian <mike@fireburn.co.uk>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200511225849.1311869-1-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Arvind Sankar 2020-05-11 18:58:49 -04:00 committed by Ard Biesheuvel
parent 3d8c11efd5
commit e78d334a54
1 changed files with 8 additions and 8 deletions
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16
arch/x86/boot/tools/build.c
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@ -59,14 +59,14 @@ u8 buf[SETUP_SECT_MAX*512];
#define PECOFF_COMPAT_RESERVE 0x0
#endif
unsigned long efi32_stub_entry;
unsigned long efi64_stub_entry;
unsigned long efi_pe_entry;
unsigned long efi32_pe_entry;
unsigned long kernel_info;
unsigned long startup_64;
unsigned long _ehead;
unsigned long _end;
static unsigned long efi32_stub_entry;
static unsigned long efi64_stub_entry;
static unsigned long efi_pe_entry;
static unsigned long efi32_pe_entry;
static unsigned long kernel_info;
static unsigned long startup_64;
static unsigned long _ehead;
static unsigned long _end;
/*----------------------------------------------------------------------*/