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[173.164.112.133]) by smtp.gmail.com with ESMTPSA id 8sm26161856pfs.50.2019.04.23.16.26.23 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 23 Apr 2019 16:26:23 -0700 (PDT) Date: Tue, 23 Apr 2019 16:26:22 -0700 From: Kees Cook To: Catalin Marinas Cc: Will Deacon , Mark Rutland , Arnd Bergmann , Alex Matveev , Ard Biesheuvel , Nick Desaulniers , Yury Norov , Matthias Kaehlcke , Sami Tolvanen , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v4] arm64: sysreg: Make mrs_s and msr_s macros work with Clang and LTO Message-ID: <20190423232622.GA11776@beast> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Co-developed-by: Yury Norov Co-developed-by: Sami Tolvanen Signed-off-by: Kees Cook --- v4: move to using preprocessor entirely, split constraints for "rZ" case. v3: added more uses in irqflags, updated commit log, based on discussion in https://lore.kernel.org/patchwork/patch/851580/ --- arch/arm64/include/asm/irqflags.h | 8 ++--- arch/arm64/include/asm/kvm_hyp.h | 4 +-- arch/arm64/include/asm/sysreg.h | 51 +++++++++++++++++++++++-------- 3 files changed, 44 insertions(+), 19 deletions(-) diff --git a/arch/arm64/include/asm/irqflags.h b/arch/arm64/include/asm/irqflags.h index 43d8366c1e87..d359f28765cb 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) "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), 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(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) "dsb sy", ARM64_HAS_IRQ_PRIO_MASKING) : "+r" (flags) diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h index 4da765f2cca5..f2e681d657bb 100644 --- a/arch/arm64/include/asm/kvm_hyp.h +++ b/arch/arm64/include/asm/kvm_hyp.h @@ -30,7 +30,7 @@ ({ \ u64 reg; \ asm volatile(ALTERNATIVE("mrs %0, " __stringify(r##nvh),\ - "mrs_s %0, " __stringify(r##vh),\ + __mrs_s(r##vh), \ ARM64_HAS_VIRT_HOST_EXTN) \ : "=r" (reg)); \ reg; \ @@ -40,7 +40,7 @@ do { \ u64 __val = (u64)(v); \ asm volatile(ALTERNATIVE("msr " __stringify(r##nvh) ", %x0",\ - "msr_s " __stringify(r##vh) ", %x0",\ + __msr_s_x0(r##vh), \ ARM64_HAS_VIRT_HOST_EXTN) \ : : "rZ" (__val)); \ } while (0) diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index 5b267dec6194..21d8f6dd4d79 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -746,20 +746,45 @@ #include #include -asm( -" .irp num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30\n" -" .equ .L__reg_num_x\\num, \\num\n" -" .endr\n" +#define __DEFINE_MRS_MSR_S_REGNUM \ +" .irp num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30\n" \ +" .equ .L__reg_num_x\\num, \\num\n" \ +" .endr\n" \ " .equ .L__reg_num_xzr, 31\n" -"\n" -" .macro mrs_s, rt, sreg\n" - __emit_inst(0xd5200000|(\\sreg)|(.L__reg_num_\\rt)) + +#define DEFINE_MRS_S \ + __DEFINE_MRS_MSR_S_REGNUM \ +" .macro mrs_s, rt, sreg\n" \ + __emit_inst(0xd5200000|(\\sreg)|(.L__reg_num_\\rt)) \ " .endm\n" -"\n" -" .macro msr_s, sreg, rt\n" - __emit_inst(0xd5000000|(\\sreg)|(.L__reg_num_\\rt)) + +#define DEFINE_MSR_S \ + __DEFINE_MRS_MSR_S_REGNUM \ +" .macro msr_s, sreg, rt\n" \ + __emit_inst(0xd5000000|(\\sreg)|(.L__reg_num_\\rt)) \ " .endm\n" -); + +#define UNDEFINE_MRS_S \ +" .purgem mrs_s\n" + +#define UNDEFINE_MSR_S \ +" .purgem msr_s\n" + +#define __mrs_s(r) \ + DEFINE_MRS_S \ +" mrs_s %0, " __stringify(r) "\n" \ + UNDEFINE_MRS_S + +#define __msr_s(r) \ + DEFINE_MSR_S \ +" msr_s " __stringify(r) ", %0\n" \ + UNDEFINE_MSR_S + +/* For use with "rZ" constraints. */ +#define __msr_s_x0(r) \ + DEFINE_MSR_S \ +" msr_s " __stringify(r) ", %x0\n" \ + UNDEFINE_MSR_S /* * Unlike read_cpuid, calls to read_sysreg are never expected to be @@ -787,13 +812,13 @@ asm( */ #define read_sysreg_s(r) ({ \ u64 __val; \ - asm volatile("mrs_s %0, " __stringify(r) : "=r" (__val)); \ + asm volatile(__mrs_s(r) : "=r" (__val)); \ __val; \ }) #define write_sysreg_s(v, r) do { \ u64 __val = (u64)(v); \ - asm volatile("msr_s " __stringify(r) ", %x0" : : "rZ" (__val)); \ + asm volatile(__msr_s_x0(r) : : "rZ" (__val)); \ } while (0) /* -- 2.17.1 -- Kees Cook