From be77e1d5fe1abaaf70d886719a4084ea9c0c5eec Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Thu, 21 Apr 2022 08:17:07 -0700 Subject: [PATCH] target/nios2: Clean up handling of tlbmisc in do_exception The 4 lower bits, D, PERM, BAD, DBL, are unconditionally set on any exception with EH=0, or so says Table 42 (Processor Status After Taking Exception). We currently do not set PERM or BAD at all, and only set/clear DBL for tlb miss, and do not clear DBL for any other exception. It is a bit confusing to set D in tlb_fill and the rest during do_interrupt, so move the setting of D to do_interrupt as well. To do this, split EXP_TLBD into two cases, EXCP_TLB_X and EXCP_TLB_D, which allows us to distinguish them during do_interrupt. Choose a value for EXCP_TLB_D such that when truncated it produces the correct value for exception.CAUSE. Rename EXCP_TLB[RWX] to EXCP_PERM_[RWX], to emphasize that the exception is permissions related. Rename EXCP_SUPER[AD] to EXCP_SUPERA_[DX] to emphasize that they are both "supervisor address" exceptions, data and execute. Retain the setting of tlbmisc.WE for the fast-tlb-miss path, as it is being relied upon, but remove it from the permission path. Reviewed-by: Peter Maydell Signed-off-by: Richard Henderson Message-Id: <20220421151735.31996-37-richard.henderson@linaro.org> --- target/nios2/cpu.h | 13 +++---- target/nios2/helper.c | 97 +++++++++++++++++++++++++++++++++++---------------- 2 files changed, 73 insertions(+), 37 deletions(-) diff --git a/target/nios2/cpu.h b/target/nios2/cpu.h index 01cead5502..0027416742 100644 --- a/target/nios2/cpu.h +++ b/target/nios2/cpu.h @@ -166,13 +166,14 @@ FIELD(CR_TLBMISC, EE, 24, 1) #define EXCP_UNALIGN 6 #define EXCP_UNALIGND 7 #define EXCP_DIV 8 -#define EXCP_SUPERA 9 +#define EXCP_SUPERA_X 9 #define EXCP_SUPERI 10 -#define EXCP_SUPERD 11 -#define EXCP_TLBD 12 -#define EXCP_TLBX 13 -#define EXCP_TLBR 14 -#define EXCP_TLBW 15 +#define EXCP_SUPERA_D 11 +#define EXCP_TLB_X 12 +#define EXCP_TLB_D (0x1000 | EXCP_TLB_X) +#define EXCP_PERM_X 13 +#define EXCP_PERM_R 14 +#define EXCP_PERM_W 15 #define EXCP_MPUI 16 #define EXCP_MPUD 17 diff --git a/target/nios2/helper.c b/target/nios2/helper.c index 3d9869453b..4d9085f22f 100644 --- a/target/nios2/helper.c +++ b/target/nios2/helper.c @@ -29,7 +29,8 @@ #include "semihosting/semihost.h" -static void do_exception(Nios2CPU *cpu, uint32_t exception_addr, bool is_break) +static void do_exception(Nios2CPU *cpu, uint32_t exception_addr, + uint32_t tlbmisc_set, bool is_break) { CPUNios2State *env = &cpu->env; CPUState *cs = CPU(cpu); @@ -48,6 +49,16 @@ static void do_exception(Nios2CPU *cpu, uint32_t exception_addr, bool is_break) if (cpu->mmu_present) { new_status |= CR_STATUS_EH; + + /* + * There are 4 bits that are always written. + * Explicitly clear them, to be set via the argument. + */ + env->ctrl[CR_TLBMISC] &= ~(CR_TLBMISC_D | + CR_TLBMISC_PERM | + CR_TLBMISC_BAD | + CR_TLBMISC_DBL); + env->ctrl[CR_TLBMISC] |= tlbmisc_set; } } @@ -63,13 +74,14 @@ static void do_exception(Nios2CPU *cpu, uint32_t exception_addr, bool is_break) static void do_iic_irq(Nios2CPU *cpu) { - do_exception(cpu, cpu->exception_addr, false); + do_exception(cpu, cpu->exception_addr, 0, false); } void nios2_cpu_do_interrupt(CPUState *cs) { Nios2CPU *cpu = NIOS2_CPU(cs); CPUNios2State *env = &cpu->env; + uint32_t tlbmisc_set = 0; if (qemu_loglevel_mask(CPU_LOG_INT)) { const char *name = NULL; @@ -78,20 +90,21 @@ void nios2_cpu_do_interrupt(CPUState *cs) case EXCP_IRQ: name = "interrupt"; break; - case EXCP_TLBD: + case EXCP_TLB_X: + case EXCP_TLB_D: if (env->ctrl[CR_STATUS] & CR_STATUS_EH) { name = "TLB MISS (double)"; } else { name = "TLB MISS (fast)"; } break; - case EXCP_TLBR: - case EXCP_TLBW: - case EXCP_TLBX: + case EXCP_PERM_R: + case EXCP_PERM_W: + case EXCP_PERM_X: name = "TLB PERM"; break; - case EXCP_SUPERA: - case EXCP_SUPERD: + case EXCP_SUPERA_X: + case EXCP_SUPERA_D: name = "SUPERVISOR (address)"; break; case EXCP_SUPERI: @@ -129,38 +142,57 @@ void nios2_cpu_do_interrupt(CPUState *cs) do_iic_irq(cpu); break; - case EXCP_TLBD: - if ((env->ctrl[CR_STATUS] & CR_STATUS_EH) == 0) { - env->ctrl[CR_TLBMISC] &= ~CR_TLBMISC_DBL; - env->ctrl[CR_TLBMISC] |= CR_TLBMISC_WE; - do_exception(cpu, cpu->fast_tlb_miss_addr, false); + case EXCP_TLB_D: + tlbmisc_set = CR_TLBMISC_D; + /* fall through */ + case EXCP_TLB_X: + if (env->ctrl[CR_STATUS] & CR_STATUS_EH) { + tlbmisc_set |= CR_TLBMISC_DBL; + /* + * Normally, we don't write to tlbmisc unless !EH, + * so do it manually for the double-tlb miss exception. + */ + env->ctrl[CR_TLBMISC] &= ~(CR_TLBMISC_D | + CR_TLBMISC_PERM | + CR_TLBMISC_BAD); + env->ctrl[CR_TLBMISC] |= tlbmisc_set; + do_exception(cpu, cpu->exception_addr, 0, false); } else { - env->ctrl[CR_TLBMISC] |= CR_TLBMISC_DBL; - do_exception(cpu, cpu->exception_addr, false); + tlbmisc_set |= CR_TLBMISC_WE; + do_exception(cpu, cpu->fast_tlb_miss_addr, tlbmisc_set, false); } break; - case EXCP_TLBR: - case EXCP_TLBW: - case EXCP_TLBX: - if ((env->ctrl[CR_STATUS] & CR_STATUS_EH) == 0) { - env->ctrl[CR_TLBMISC] |= CR_TLBMISC_WE; + case EXCP_PERM_R: + case EXCP_PERM_W: + tlbmisc_set = CR_TLBMISC_D; + /* fall through */ + case EXCP_PERM_X: + tlbmisc_set |= CR_TLBMISC_PERM; + if (!(env->ctrl[CR_STATUS] & CR_STATUS_EH)) { + tlbmisc_set |= CR_TLBMISC_WE; } - do_exception(cpu, cpu->exception_addr, false); + do_exception(cpu, cpu->exception_addr, tlbmisc_set, false); + break; + + case EXCP_SUPERA_D: + case EXCP_UNALIGN: + tlbmisc_set = CR_TLBMISC_D; + /* fall through */ + case EXCP_SUPERA_X: + case EXCP_UNALIGND: + tlbmisc_set |= CR_TLBMISC_BAD; + do_exception(cpu, cpu->exception_addr, tlbmisc_set, false); break; - case EXCP_SUPERA: case EXCP_SUPERI: - case EXCP_SUPERD: case EXCP_ILLEGAL: case EXCP_TRAP: - case EXCP_UNALIGN: - case EXCP_UNALIGND: - do_exception(cpu, cpu->exception_addr, false); + do_exception(cpu, cpu->exception_addr, 0, false); break; case EXCP_BREAK: - do_exception(cpu, cpu->exception_addr, true); + do_exception(cpu, cpu->exception_addr, 0, true); break; case EXCP_SEMIHOST: @@ -215,7 +247,7 @@ bool nios2_cpu_tlb_fill(CPUState *cs, vaddr address, int size, { Nios2CPU *cpu = NIOS2_CPU(cs); CPUNios2State *env = &cpu->env; - unsigned int excp = EXCP_TLBD; + unsigned int excp; target_ulong vaddr, paddr; Nios2MMULookup lu; unsigned int hit; @@ -242,7 +274,8 @@ bool nios2_cpu_tlb_fill(CPUState *cs, vaddr address, int size, if (probe) { return false; } - cs->exception_index = EXCP_SUPERA; + cs->exception_index = (access_type == MMU_INST_FETCH + ? EXCP_SUPERA_X : EXCP_SUPERA_D); env->ctrl[CR_BADADDR] = address; cpu_loop_exit_restore(cs, retaddr); } @@ -263,8 +296,10 @@ bool nios2_cpu_tlb_fill(CPUState *cs, vaddr address, int size, } /* Permission violation */ - excp = (access_type == MMU_DATA_LOAD ? EXCP_TLBR : - access_type == MMU_DATA_STORE ? EXCP_TLBW : EXCP_TLBX); + excp = (access_type == MMU_DATA_LOAD ? EXCP_PERM_R : + access_type == MMU_DATA_STORE ? EXCP_PERM_W : EXCP_PERM_X); + } else { + excp = (access_type == MMU_INST_FETCH ? EXCP_TLB_X: EXCP_TLB_D); } if (probe) { -- 2.11.0