From: Kristina Martsenko Date: Tue, 9 May 2023 14:22:31 +0000 (+0100) Subject: arm64: mops: handle MOPS exceptions X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=8536ceaa747174ded7983f13906b225e0c33ac51;p=linux.git arm64: mops: handle MOPS exceptions The memory copy/set instructions added as part of FEAT_MOPS can take an exception (e.g. page fault) part-way through their execution and resume execution afterwards. If however the task is re-scheduled and execution resumes on a different CPU, then the CPU may take a new type of exception to indicate this. This is because the architecture allows two options (Option A and Option B) to implement the instructions and a heterogeneous system can have different implementations between CPUs. In this case the OS has to reset the registers and restart execution from the prologue instruction. The algorithm for doing this is provided as part of the Arm ARM. Add an exception handler for the new exception and wire it up for userspace tasks. Reviewed-by: Catalin Marinas Signed-off-by: Kristina Martsenko Link: https://lore.kernel.org/r/20230509142235.3284028-8-kristina.martsenko@arm.com Signed-off-by: Catalin Marinas --- diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h index 8487aec9b6587..ca954f5668617 100644 --- a/arch/arm64/include/asm/esr.h +++ b/arch/arm64/include/asm/esr.h @@ -47,7 +47,7 @@ #define ESR_ELx_EC_DABT_LOW (0x24) #define ESR_ELx_EC_DABT_CUR (0x25) #define ESR_ELx_EC_SP_ALIGN (0x26) -/* Unallocated EC: 0x27 */ +#define ESR_ELx_EC_MOPS (0x27) #define ESR_ELx_EC_FP_EXC32 (0x28) /* Unallocated EC: 0x29 - 0x2B */ #define ESR_ELx_EC_FP_EXC64 (0x2C) @@ -356,6 +356,15 @@ #define ESR_ELx_SME_ISS_ZA_DISABLED 3 #define ESR_ELx_SME_ISS_ZT_DISABLED 4 +/* ISS field definitions for MOPS exceptions */ +#define ESR_ELx_MOPS_ISS_MEM_INST (UL(1) << 24) +#define ESR_ELx_MOPS_ISS_FROM_EPILOGUE (UL(1) << 18) +#define ESR_ELx_MOPS_ISS_WRONG_OPTION (UL(1) << 17) +#define ESR_ELx_MOPS_ISS_OPTION_A (UL(1) << 16) +#define ESR_ELx_MOPS_ISS_DESTREG(esr) (((esr) & (UL(0x1f) << 10)) >> 10) +#define ESR_ELx_MOPS_ISS_SRCREG(esr) (((esr) & (UL(0x1f) << 5)) >> 5) +#define ESR_ELx_MOPS_ISS_SIZEREG(esr) (((esr) & (UL(0x1f) << 0)) >> 0) + #ifndef __ASSEMBLY__ #include diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h index e73af709cb7ad..72e83af0135fc 100644 --- a/arch/arm64/include/asm/exception.h +++ b/arch/arm64/include/asm/exception.h @@ -77,6 +77,7 @@ void do_el0_svc(struct pt_regs *regs); void do_el0_svc_compat(struct pt_regs *regs); void do_el0_fpac(struct pt_regs *regs, unsigned long esr); void do_el1_fpac(struct pt_regs *regs, unsigned long esr); +void do_el0_mops(struct pt_regs *regs, unsigned long esr); void do_serror(struct pt_regs *regs, unsigned long esr); void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags); diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c index 3af3c01c93a65..a8ec174e5b0e6 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -611,6 +611,14 @@ static void noinstr el0_bti(struct pt_regs *regs) exit_to_user_mode(regs); } +static void noinstr el0_mops(struct pt_regs *regs, unsigned long esr) +{ + enter_from_user_mode(regs); + local_daif_restore(DAIF_PROCCTX); + do_el0_mops(regs, esr); + exit_to_user_mode(regs); +} + static void noinstr el0_inv(struct pt_regs *regs, unsigned long esr) { enter_from_user_mode(regs); @@ -688,6 +696,9 @@ asmlinkage void noinstr el0t_64_sync_handler(struct pt_regs *regs) case ESR_ELx_EC_BTI: el0_bti(regs); break; + case ESR_ELx_EC_MOPS: + el0_mops(regs, esr); + break; case ESR_ELx_EC_BREAKPT_LOW: case ESR_ELx_EC_SOFTSTP_LOW: case ESR_ELx_EC_WATCHPT_LOW: diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 4bb1b8f472982..32dc692bffd39 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -514,6 +514,57 @@ void do_el1_fpac(struct pt_regs *regs, unsigned long esr) die("Oops - FPAC", regs, esr); } +void do_el0_mops(struct pt_regs *regs, unsigned long esr) +{ + bool wrong_option = esr & ESR_ELx_MOPS_ISS_WRONG_OPTION; + bool option_a = esr & ESR_ELx_MOPS_ISS_OPTION_A; + int dstreg = ESR_ELx_MOPS_ISS_DESTREG(esr); + int srcreg = ESR_ELx_MOPS_ISS_SRCREG(esr); + int sizereg = ESR_ELx_MOPS_ISS_SIZEREG(esr); + unsigned long dst, src, size; + + dst = pt_regs_read_reg(regs, dstreg); + src = pt_regs_read_reg(regs, srcreg); + size = pt_regs_read_reg(regs, sizereg); + + /* + * Put the registers back in the original format suitable for a + * prologue instruction, using the generic return routine from the + * Arm ARM (DDI 0487I.a) rules CNTMJ and MWFQH. + */ + if (esr & ESR_ELx_MOPS_ISS_MEM_INST) { + /* SET* instruction */ + if (option_a ^ wrong_option) { + /* Format is from Option A; forward set */ + pt_regs_write_reg(regs, dstreg, dst + size); + pt_regs_write_reg(regs, sizereg, -size); + } + } else { + /* CPY* instruction */ + if (!(option_a ^ wrong_option)) { + /* Format is from Option B */ + if (regs->pstate & PSR_N_BIT) { + /* Backward copy */ + pt_regs_write_reg(regs, dstreg, dst - size); + pt_regs_write_reg(regs, srcreg, src - size); + } + } else { + /* Format is from Option A */ + if (size & BIT(63)) { + /* Forward copy */ + pt_regs_write_reg(regs, dstreg, dst + size); + pt_regs_write_reg(regs, srcreg, src + size); + pt_regs_write_reg(regs, sizereg, -size); + } + } + } + + if (esr & ESR_ELx_MOPS_ISS_FROM_EPILOGUE) + regs->pc -= 8; + else + regs->pc -= 4; +} + #define __user_cache_maint(insn, address, res) \ if (address >= TASK_SIZE_MAX) { \ res = -EFAULT; \ @@ -824,6 +875,7 @@ static const char *esr_class_str[] = { [ESR_ELx_EC_DABT_LOW] = "DABT (lower EL)", [ESR_ELx_EC_DABT_CUR] = "DABT (current EL)", [ESR_ELx_EC_SP_ALIGN] = "SP Alignment", + [ESR_ELx_EC_MOPS] = "MOPS", [ESR_ELx_EC_FP_EXC32] = "FP (AArch32)", [ESR_ELx_EC_FP_EXC64] = "FP (AArch64)", [ESR_ELx_EC_SERROR] = "SError",