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| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2022-06-09 00:17:32 -0700 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-06-13 10:15:04 +0200 |
| commit | e32683c6f7d22ba624e0bfc58b02cf3348bdca63 (patch) | |
| tree | 83d8a208fd9dfb91a46c153e0b788df996fe79f2 /arch/x86/kernel/setup.c | |
| parent | b13baccc3850ca8b8cccbf8ed9912dbaa0fdf7f3 (diff) | |
| download | linux-next-e32683c6f7d22ba624e0bfc58b02cf3348bdca63.tar.gz | |
x86/mm: Fix RESERVE_BRK() for older binutils
With binutils 2.26, RESERVE_BRK() causes a build failure:
/tmp/ccnGOKZ5.s: Assembler messages:
/tmp/ccnGOKZ5.s:98: Error: missing ')'
/tmp/ccnGOKZ5.s:98: Error: missing ')'
/tmp/ccnGOKZ5.s:98: Error: missing ')'
/tmp/ccnGOKZ5.s:98: Error: junk at end of line, first unrecognized
character is `U'
The problem is this line:
RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE)
Specifically, the INIT_PGT_BUF_SIZE macro which (via PAGE_SIZE's use
_AC()) has a "1UL", which makes older versions of the assembler unhappy.
Unfortunately the _AC() macro doesn't work for inline asm.
Inline asm was only needed here to convince the toolchain to add the
STT_NOBITS flag. However, if a C variable is placed in a section whose
name is prefixed with ".bss", GCC and Clang automatically set
STT_NOBITS. In fact, ".bss..page_aligned" already relies on this trick.
So fix the build failure (and simplify the macro) by allocating the
variable in C.
Also, add NOLOAD to the ".brk" output section clause in the linker
script. This is a failsafe in case the ".bss" prefix magic trick ever
stops working somehow. If there's a section type mismatch, the GNU
linker will force the ".brk" output section to be STT_NOBITS. The LLVM
linker will fail with a "section type mismatch" error.
Note this also changes the name of the variable from .brk.##name to
__brk_##name. The variable names aren't actually used anywhere, so it's
harmless.
Fixes: a1e2c031ec39 ("x86/mm: Simplify RESERVE_BRK()")
Reported-by: Joe Damato <jdamato@fastly.com>
Reported-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Joe Damato <jdamato@fastly.com>
Link: https://lore.kernel.org/r/22d07a44c80d8e8e1e82b9a806ddc8c6bbb2606e.1654759036.git.jpoimboe@kernel.org
Diffstat (limited to 'arch/x86/kernel/setup.c')
| -rw-r--r-- | arch/x86/kernel/setup.c | 5 |
1 files changed, 0 insertions, 5 deletions
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 3ebb85327edb..bd6c6fd373ae 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -67,11 +67,6 @@ RESERVE_BRK(dmi_alloc, 65536); #endif -/* - * Range of the BSS area. The size of the BSS area is determined - * at link time, with RESERVE_BRK() facility reserving additional - * chunks. - */ unsigned long _brk_start = (unsigned long)__brk_base; unsigned long _brk_end = (unsigned long)__brk_base; |