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[173.164.112.133]) by smtp.gmail.com with ESMTPSA id q128sm79883144pga.60.2019.04.15.07.38.22 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 15 Apr 2019 07:38:23 -0700 (PDT) Date: Mon, 15 Apr 2019 07:38:21 -0700 From: Kees Cook To: Catalin Marinas Cc: Will Deacon , Alex Matveev , Ard Biesheuvel , linux-arm-kernel@lists.infradead.org, Nick Desaulniers , Yury Norov , Matthias Kaehlcke , Sami Tolvanen , linux-kernel@vger.kernel.org Subject: [PATCH v3] arm64: sysreg: make mrs_s and msr_s macros work with Clang and LTO Message-ID: <20190415143821.GA46880@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 From: Alex Matveev 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. Signed-off-by: Alex Matveev Signed-off-by: Yury Norov Signed-off-by: Sami Tolvanen Signed-off-by: Kees Cook --- v3: split out patch as stand-alone, 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 | 12 +++++-- arch/arm64/include/asm/kvm_hyp.h | 8 +++-- arch/arm64/include/asm/sysreg.h | 55 +++++++++++++++++++++---------- 3 files changed, 53 insertions(+), 22 deletions(-) diff --git a/arch/arm64/include/asm/irqflags.h b/arch/arm64/include/asm/irqflags.h index 43d8366c1e87..06d3987d1546 100644 --- a/arch/arm64/include/asm/irqflags.h +++ b/arch/arm64/include/asm/irqflags.h @@ -43,7 +43,9 @@ static inline void arch_local_irq_enable(void) asm volatile(ALTERNATIVE( "msr daifclr, #2 // arch_local_irq_enable\n" "nop", + DEFINE_MSR_S "msr_s " __stringify(SYS_ICC_PMR_EL1) ",%0\n" + UNDEFINE_MSR_S "dsb sy", ARM64_HAS_IRQ_PRIO_MASKING) : @@ -55,7 +57,9 @@ 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", + DEFINE_MSR_S + "msr_s " __stringify(SYS_ICC_PMR_EL1) ", %0\n" + UNDEFINE_MSR_S, ARM64_HAS_IRQ_PRIO_MASKING) : : "r" ((unsigned long) GIC_PRIO_IRQOFF) @@ -85,8 +89,10 @@ static inline unsigned long arch_local_save_flags(void) asm volatile(ALTERNATIVE( "mov %0, %1\n" "nop\n" - "nop", + "nop\n", + DEFINE_MRS_S "mrs_s %0, " __stringify(SYS_ICC_PMR_EL1) "\n" + UNDEFINE_MRS_S "ands %1, %1, " __stringify(PSR_I_BIT) "\n" "csel %0, %0, %2, eq", ARM64_HAS_IRQ_PRIO_MASKING) @@ -116,7 +122,9 @@ static inline void arch_local_irq_restore(unsigned long flags) asm volatile(ALTERNATIVE( "msr daif, %0\n" "nop", + DEFINE_MSR_S "msr_s " __stringify(SYS_ICC_PMR_EL1) ", %0\n" + UNDEFINE_MSR_S "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..9d0e7f546240 100644 --- a/arch/arm64/include/asm/kvm_hyp.h +++ b/arch/arm64/include/asm/kvm_hyp.h @@ -30,7 +30,9 @@ ({ \ u64 reg; \ asm volatile(ALTERNATIVE("mrs %0, " __stringify(r##nvh),\ - "mrs_s %0, " __stringify(r##vh),\ + DEFINE_MRS_S \ + "mrs_s %0, " __stringify(r##vh) "\n"\ + UNDEFINE_MRS_S, \ ARM64_HAS_VIRT_HOST_EXTN) \ : "=r" (reg)); \ reg; \ @@ -40,7 +42,9 @@ do { \ u64 __val = (u64)(v); \ asm volatile(ALTERNATIVE("msr " __stringify(r##nvh) ", %x0",\ - "msr_s " __stringify(r##vh) ", %x0",\ + DEFINE_MSR_S \ + "msr_s " __stringify(r##vh) ", %x0\n"\ + UNDEFINE_MSR_S, \ 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..e9f64c237a7c 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -746,20 +746,39 @@ #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, v) \ + DEFINE_MRS_S \ +" mrs_s %0, " __stringify(r) "\n" \ + UNDEFINE_MRS_S : "=r" (v) + +#define __msr_s(r, v) \ + DEFINE_MSR_S \ +" msr_s " __stringify(r) ", %x0\n" \ + UNDEFINE_MSR_S : : "rZ" (v) /* * Unlike read_cpuid, calls to read_sysreg are never expected to be @@ -785,15 +804,15 @@ asm( * For registers without architectural names, or simply unsupported by * GAS. */ -#define read_sysreg_s(r) ({ \ - u64 __val; \ - asm volatile("mrs_s %0, " __stringify(r) : "=r" (__val)); \ - __val; \ +#define read_sysreg_s(r) ({ \ + u64 __val; \ + asm volatile(__mrs_s(r, __val)); \ + __val; \ }) -#define write_sysreg_s(v, r) do { \ - u64 __val = (u64)(v); \ - asm volatile("msr_s " __stringify(r) ", %x0" : : "rZ" (__val)); \ +#define write_sysreg_s(v, r) do { \ + u64 __val = (u64)(v); \ + asm volatile(__msr_s(r, __val)); \ } while (0) /* -- 2.17.1 -- Kees Cook