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| author | Kees Cook <keescook@chromium.org> | 2019-04-24 19:55:37 +0300 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2019-04-25 16:59:49 +0300 |
| commit | be604c616ca71cbf5c860d0cfa4595128ab74189 (patch) | |
| tree | db3fb80ae32a8238557a1cc07c30f1863ca5187c /arch/arm64/include/asm/irqflags.h | |
| parent | 06a916feca2b262ab0c1a2aeb68882f4b1108a07 (diff) | |
| download | linux-be604c616ca71cbf5c860d0cfa4595128ab74189.tar.xz | |
arm64: sysreg: Make mrs_s and msr_s macros work with Clang and LTO
Clang's integrated assembler does not allow assembly macros defined
in one inline asm block using the .macro directive to be used across
separate asm blocks. LLVM developers consider this a feature and not a
bug, recommending code refactoring:
https://bugs.llvm.org/show_bug.cgi?id=19749
As binutils doesn't allow macros to be redefined, this change uses
UNDEFINE_MRS_S and UNDEFINE_MSR_S to define corresponding macros
in-place and workaround gcc and clang limitations on redefining macros
across different assembler blocks.
Specifically, the current state after preprocessing looks like this:
asm volatile(".macro mXX_s ... .endm");
void f()
{
asm volatile("mXX_s a, b");
}
With GCC, it gives macro redefinition error because sysreg.h is included
in multiple source files, and assembler code for all of them is later
combined for LTO (I've seen an intermediate file with hundreds of
identical definitions).
With clang, it gives macro undefined error because clang doesn't allow
sharing macros between inline asm statements.
I also seem to remember catching another sort of undefined error with
GCC due to reordering of macro definition asm statement and generated
asm code for function that uses the macro.
The solution with defining and undefining for each use, while certainly
not elegant, satisfies both GCC and clang, LTO and non-LTO.
Co-developed-by: Alex Matveev <alxmtvv@gmail.com>
Co-developed-by: Yury Norov <ynorov@caviumnetworks.com>
Co-developed-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/irqflags.h')
| -rw-r--r-- | arch/arm64/include/asm/irqflags.h | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/irqflags.h b/arch/arm64/include/asm/irqflags.h index 43d8366c1e87..629963189085 100644 --- a/arch/arm64/include/asm/irqflags.h +++ b/arch/arm64/include/asm/irqflags.h @@ -43,7 +43,7 @@ static inline void arch_local_irq_enable(void) asm volatile(ALTERNATIVE( "msr daifclr, #2 // arch_local_irq_enable\n" "nop", - "msr_s " __stringify(SYS_ICC_PMR_EL1) ",%0\n" + __msr_s(SYS_ICC_PMR_EL1, "%0") "dsb sy", ARM64_HAS_IRQ_PRIO_MASKING) : @@ -55,7 +55,7 @@ static inline void arch_local_irq_disable(void) { asm volatile(ALTERNATIVE( "msr daifset, #2 // arch_local_irq_disable", - "msr_s " __stringify(SYS_ICC_PMR_EL1) ", %0", + __msr_s(SYS_ICC_PMR_EL1, "%0"), ARM64_HAS_IRQ_PRIO_MASKING) : : "r" ((unsigned long) GIC_PRIO_IRQOFF) @@ -86,7 +86,7 @@ static inline unsigned long arch_local_save_flags(void) "mov %0, %1\n" "nop\n" "nop", - "mrs_s %0, " __stringify(SYS_ICC_PMR_EL1) "\n" + __mrs_s("%0", SYS_ICC_PMR_EL1) "ands %1, %1, " __stringify(PSR_I_BIT) "\n" "csel %0, %0, %2, eq", ARM64_HAS_IRQ_PRIO_MASKING) @@ -116,7 +116,7 @@ static inline void arch_local_irq_restore(unsigned long flags) asm volatile(ALTERNATIVE( "msr daif, %0\n" "nop", - "msr_s " __stringify(SYS_ICC_PMR_EL1) ", %0\n" + __msr_s(SYS_ICC_PMR_EL1, "%0") "dsb sy", ARM64_HAS_IRQ_PRIO_MASKING) : "+r" (flags) |