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arm64: avoid BUILD_BUG_ON() in alternative-macros

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Nathan reports that the build fails when using clang and LTO:

|  In file included from kernel/bounds.c:10:
|  In file included from ./include/linux/page-flags.h:10:
|  In file included from ./include/linux/bug.h:5:
|  In file included from ./arch/arm64/include/asm/bug.h:26:
|  In file included from ./include/asm-generic/bug.h:5:
|  In file included from ./include/linux/compiler.h:248:
|  In file included from ./arch/arm64/include/asm/rwonce.h:11:
|  ./arch/arm64/include/asm/alternative-macros.h:224:2: error: call to undeclared function 'BUILD_BUG_ON'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
|          BUILD_BUG_ON(feature >= ARM64_NCAPS);
|          ^
|  ./arch/arm64/include/asm/alternative-macros.h:241:2: error: call to undeclared function 'BUILD_BUG_ON'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
|          BUILD_BUG_ON(feature >= ARM64_NCAPS);
|          ^
|  2 errors generated.

... the problem being that when LTO is enabled, <asm/rwonce.h> includes
<asm/alternative-macros.h>, and causes a circular include dependency
through <linux/bug.h>. This manifests as BUILD_BUG_ON() not being
defined when used within <asm/alternative-macros.h>.

This patch avoids the problem and simplifies the include dependencies by
using compiletime_assert() instead of BUILD_BUG_ON().

Signed-off-by: Mark Rutland <[email protected]>
Fixes: 21fb26bfb0 ("arm64: alternatives: add alternative_has_feature_*()")
Reported-by: Nathan Chancellor <[email protected]>
Tested-by: Nathan Chancellor <[email protected]>
Link: http://lore.kernel.org/r/[email protected]
Cc: Ard Biesheuvel <[email protected]>
Cc: James Morse <[email protected]>
Cc: Joey Gouly <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Will Deacon <[email protected]>
Reviewed-by: Ard Biesheuvel <[email protected]>
Acked-by: Marc Zyngier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>
This commit is contained in:
Mark Rutland authored and Catalin Marinas committed 2022-09-21 12:41:50 +01:00
1 parent d926079f17
commit 0072dc1b53
1 file changed
+4 -3
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arch/arm64/include/asm/alternative-macros.h
+4 -3
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@@ -215,13 +215,13 @@ alternative_endif
#ifndef __ASSEMBLY__
#include <linux/bug.h>
#include <linux/types.h>
static __always_inline bool
alternative_has_feature_likely(unsigned long feature)
{
BUILD_BUG_ON(feature >= ARM64_NCAPS);
compiletime_assert(feature < ARM64_NCAPS,
"feature must be < ARM64_NCAPS");
asm_volatile_goto(
ALTERNATIVE_CB("b %l[l_no]", %[feature], alt_cb_patch_nops)
@@ -238,7 +238,8 @@ l_no:
static __always_inline bool
alternative_has_feature_unlikely(unsigned long feature)
{
BUILD_BUG_ON(feature >= ARM64_NCAPS);
compiletime_assert(feature < ARM64_NCAPS,
"feature must be < ARM64_NCAPS");
asm_volatile_goto(
ALTERNATIVE("nop", "b %l[l_yes]", %[feature])