From 0e92818887deef2300255300af57bb58a6af1ad4 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Tue, 12 Sep 2023 15:04:29 +0100 Subject: [PATCH] target/arm: Implement the SET* instructions Implement the SET* instructions which collectively implement a "memset" operation. These come in a set of three, eg SETP (prologue), SETM (main), SETE (epilogue), and each of those has different flavours to indicate whether memory accesses should be unpriv or non-temporal. This commit does not include the "memset with tag setting" SETG* instructions. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Message-id: 20230912140434.1333369-8-peter.maydell@linaro.org --- target/arm/tcg/a64.decode | 16 ++ target/arm/tcg/helper-a64.c | 344 +++++++++++++++++++++++++++++++++++++++++ target/arm/tcg/helper-a64.h | 4 + target/arm/tcg/translate-a64.c | 49 ++++++ 4 files changed, 413 insertions(+) diff --git a/target/arm/tcg/a64.decode b/target/arm/tcg/a64.decode index 7111317302..c2a97328ee 100644 --- a/target/arm/tcg/a64.decode +++ b/target/arm/tcg/a64.decode @@ -554,3 +554,19 @@ LDGM 11011001 11 1 ......... 00 ..... ..... @ldst_tag_mult p=0 w=0 STZ2G 11011001 11 1 ......... 01 ..... ..... @ldst_tag p=1 w=1 STZ2G 11011001 11 1 ......... 10 ..... ..... @ldst_tag p=0 w=0 STZ2G 11011001 11 1 ......... 11 ..... ..... @ldst_tag p=0 w=1 + +# Memory operations (memset, memcpy, memmove) +# Each of these comes in a set of three, eg SETP (prologue), SETM (main), +# SETE (epilogue), and each of those has different flavours to +# indicate whether memory accesses should be unpriv or non-temporal. +# We don't distinguish temporal and non-temporal accesses, but we +# do need to report it in syndrome register values. + +# Memset +&set rs rn rd unpriv nontemp +# op2 bit 1 is nontemporal bit +@set .. ......... rs:5 .. nontemp:1 unpriv:1 .. rn:5 rd:5 &set + +SETP 00 011001110 ..... 00 . . 01 ..... ..... @set +SETM 00 011001110 ..... 01 . . 01 ..... ..... @set +SETE 00 011001110 ..... 10 . . 01 ..... ..... @set diff --git a/target/arm/tcg/helper-a64.c b/target/arm/tcg/helper-a64.c index 0cf56f6dc4..24ae5ecf32 100644 --- a/target/arm/tcg/helper-a64.c +++ b/target/arm/tcg/helper-a64.c @@ -968,3 +968,347 @@ void HELPER(unaligned_access)(CPUARMState *env, uint64_t addr, arm_cpu_do_unaligned_access(env_cpu(env), addr, access_type, mmu_idx, GETPC()); } + +/* Memory operations (memset, memmove, memcpy) */ + +/* + * Return true if the CPY* and SET* insns can execute; compare + * pseudocode CheckMOPSEnabled(), though we refactor it a little. + */ +static bool mops_enabled(CPUARMState *env) +{ + int el = arm_current_el(env); + + if (el < 2 && + (arm_hcr_el2_eff(env) & (HCR_E2H | HCR_TGE)) != (HCR_E2H | HCR_TGE) && + !(arm_hcrx_el2_eff(env) & HCRX_MSCEN)) { + return false; + } + + if (el == 0) { + if (!el_is_in_host(env, 0)) { + return env->cp15.sctlr_el[1] & SCTLR_MSCEN; + } else { + return env->cp15.sctlr_el[2] & SCTLR_MSCEN; + } + } + return true; +} + +static void check_mops_enabled(CPUARMState *env, uintptr_t ra) +{ + if (!mops_enabled(env)) { + raise_exception_ra(env, EXCP_UDEF, syn_uncategorized(), + exception_target_el(env), ra); + } +} + +/* + * Return the target exception level for an exception due + * to mismatched arguments in a FEAT_MOPS copy or set. + * Compare pseudocode MismatchedCpySetTargetEL() + */ +static int mops_mismatch_exception_target_el(CPUARMState *env) +{ + int el = arm_current_el(env); + + if (el > 1) { + return el; + } + if (el == 0 && (arm_hcr_el2_eff(env) & HCR_TGE)) { + return 2; + } + if (el == 1 && (arm_hcrx_el2_eff(env) & HCRX_MCE2)) { + return 2; + } + return 1; +} + +/* + * Check whether an M or E instruction was executed with a CF value + * indicating the wrong option for this implementation. + * Assumes we are always Option A. + */ +static void check_mops_wrong_option(CPUARMState *env, uint32_t syndrome, + uintptr_t ra) +{ + if (env->CF != 0) { + syndrome |= 1 << 17; /* Set the wrong-option bit */ + raise_exception_ra(env, EXCP_UDEF, syndrome, + mops_mismatch_exception_target_el(env), ra); + } +} + +/* + * Return the maximum number of bytes we can transfer starting at addr + * without crossing a page boundary. + */ +static uint64_t page_limit(uint64_t addr) +{ + return TARGET_PAGE_ALIGN(addr + 1) - addr; +} + +/* + * Perform part of a memory set on an area of guest memory starting at + * toaddr (a dirty address) and extending for setsize bytes. + * + * Returns the number of bytes actually set, which might be less than + * setsize; the caller should loop until the whole set has been done. + * The caller should ensure that the guest registers are correct + * for the possibility that the first byte of the set encounters + * an exception or watchpoint. We guarantee not to take any faults + * for bytes other than the first. + */ +static uint64_t set_step(CPUARMState *env, uint64_t toaddr, + uint64_t setsize, uint32_t data, int memidx, + uint32_t *mtedesc, uintptr_t ra) +{ + void *mem; + + setsize = MIN(setsize, page_limit(toaddr)); + if (*mtedesc) { + uint64_t mtesize = mte_mops_probe(env, toaddr, setsize, *mtedesc); + if (mtesize == 0) { + /* Trap, or not. All CPU state is up to date */ + mte_check_fail(env, *mtedesc, toaddr, ra); + /* Continue, with no further MTE checks required */ + *mtedesc = 0; + } else { + /* Advance to the end, or to the tag mismatch */ + setsize = MIN(setsize, mtesize); + } + } + + toaddr = useronly_clean_ptr(toaddr); + /* + * Trapless lookup: returns NULL for invalid page, I/O, + * watchpoints, clean pages, etc. + */ + mem = tlb_vaddr_to_host(env, toaddr, MMU_DATA_STORE, memidx); + +#ifndef CONFIG_USER_ONLY + if (unlikely(!mem)) { + /* + * Slow-path: just do one byte write. This will handle the + * watchpoint, invalid page, etc handling correctly. + * For clean code pages, the next iteration will see + * the page dirty and will use the fast path. + */ + cpu_stb_mmuidx_ra(env, toaddr, data, memidx, ra); + return 1; + } +#endif + /* Easy case: just memset the host memory */ + memset(mem, data, setsize); + return setsize; +} + +typedef uint64_t StepFn(CPUARMState *env, uint64_t toaddr, + uint64_t setsize, uint32_t data, + int memidx, uint32_t *mtedesc, uintptr_t ra); + +/* Extract register numbers from a MOPS exception syndrome value */ +static int mops_destreg(uint32_t syndrome) +{ + return extract32(syndrome, 10, 5); +} + +static int mops_srcreg(uint32_t syndrome) +{ + return extract32(syndrome, 5, 5); +} + +static int mops_sizereg(uint32_t syndrome) +{ + return extract32(syndrome, 0, 5); +} + +/* + * Return true if TCMA and TBI bits mean we need to do MTE checks. + * We only need to do this once per MOPS insn, not for every page. + */ +static bool mte_checks_needed(uint64_t ptr, uint32_t desc) +{ + int bit55 = extract64(ptr, 55, 1); + + /* + * Note that tbi_check() returns true for "access checked" but + * tcma_check() returns true for "access unchecked". + */ + if (!tbi_check(desc, bit55)) { + return false; + } + return !tcma_check(desc, bit55, allocation_tag_from_addr(ptr)); +} + +/* + * For the Memory Set operation, our implementation chooses + * always to use "option A", where we update Xd to the final + * address in the SETP insn, and set Xn to be -(bytes remaining). + * On SETM and SETE insns we only need update Xn. + * + * @env: CPU + * @syndrome: syndrome value for mismatch exceptions + * (also contains the register numbers we need to use) + * @mtedesc: MTE descriptor word + * @stepfn: function which does a single part of the set operation + * @is_setg: true if this is the tag-setting SETG variant + */ +static void do_setp(CPUARMState *env, uint32_t syndrome, uint32_t mtedesc, + StepFn *stepfn, bool is_setg, uintptr_t ra) +{ + /* Prologue: we choose to do up to the next page boundary */ + int rd = mops_destreg(syndrome); + int rs = mops_srcreg(syndrome); + int rn = mops_sizereg(syndrome); + uint8_t data = env->xregs[rs]; + uint32_t memidx = FIELD_EX32(mtedesc, MTEDESC, MIDX); + uint64_t toaddr = env->xregs[rd]; + uint64_t setsize = env->xregs[rn]; + uint64_t stagesetsize, step; + + check_mops_enabled(env, ra); + + if (setsize > INT64_MAX) { + setsize = INT64_MAX; + } + + if (!mte_checks_needed(toaddr, mtedesc)) { + mtedesc = 0; + } + + stagesetsize = MIN(setsize, page_limit(toaddr)); + while (stagesetsize) { + env->xregs[rd] = toaddr; + env->xregs[rn] = setsize; + step = stepfn(env, toaddr, stagesetsize, data, memidx, &mtedesc, ra); + toaddr += step; + setsize -= step; + stagesetsize -= step; + } + /* Insn completed, so update registers to the Option A format */ + env->xregs[rd] = toaddr + setsize; + env->xregs[rn] = -setsize; + + /* Set NZCV = 0000 to indicate we are an Option A implementation */ + env->NF = 0; + env->ZF = 1; /* our env->ZF encoding is inverted */ + env->CF = 0; + env->VF = 0; + return; +} + +void HELPER(setp)(CPUARMState *env, uint32_t syndrome, uint32_t mtedesc) +{ + do_setp(env, syndrome, mtedesc, set_step, false, GETPC()); +} + +static void do_setm(CPUARMState *env, uint32_t syndrome, uint32_t mtedesc, + StepFn *stepfn, bool is_setg, uintptr_t ra) +{ + /* Main: we choose to do all the full-page chunks */ + CPUState *cs = env_cpu(env); + int rd = mops_destreg(syndrome); + int rs = mops_srcreg(syndrome); + int rn = mops_sizereg(syndrome); + uint8_t data = env->xregs[rs]; + uint64_t toaddr = env->xregs[rd] + env->xregs[rn]; + uint64_t setsize = -env->xregs[rn]; + uint32_t memidx = FIELD_EX32(mtedesc, MTEDESC, MIDX); + uint64_t step, stagesetsize; + + check_mops_enabled(env, ra); + + /* + * We're allowed to NOP out "no data to copy" before the consistency + * checks; we choose to do so. + */ + if (env->xregs[rn] == 0) { + return; + } + + check_mops_wrong_option(env, syndrome, ra); + + /* + * Our implementation will work fine even if we have an unaligned + * destination address, and because we update Xn every time around + * the loop below and the return value from stepfn() may be less + * than requested, we might find toaddr is unaligned. So we don't + * have an IMPDEF check for alignment here. + */ + + if (!mte_checks_needed(toaddr, mtedesc)) { + mtedesc = 0; + } + + /* Do the actual memset: we leave the last partial page to SETE */ + stagesetsize = setsize & TARGET_PAGE_MASK; + while (stagesetsize > 0) { + step = stepfn(env, toaddr, setsize, data, memidx, &mtedesc, ra); + toaddr += step; + setsize -= step; + stagesetsize -= step; + env->xregs[rn] = -setsize; + if (stagesetsize > 0 && unlikely(cpu_loop_exit_requested(cs))) { + cpu_loop_exit_restore(cs, ra); + } + } +} + +void HELPER(setm)(CPUARMState *env, uint32_t syndrome, uint32_t mtedesc) +{ + do_setm(env, syndrome, mtedesc, set_step, false, GETPC()); +} + +static void do_sete(CPUARMState *env, uint32_t syndrome, uint32_t mtedesc, + StepFn *stepfn, bool is_setg, uintptr_t ra) +{ + /* Epilogue: do the last partial page */ + int rd = mops_destreg(syndrome); + int rs = mops_srcreg(syndrome); + int rn = mops_sizereg(syndrome); + uint8_t data = env->xregs[rs]; + uint64_t toaddr = env->xregs[rd] + env->xregs[rn]; + uint64_t setsize = -env->xregs[rn]; + uint32_t memidx = FIELD_EX32(mtedesc, MTEDESC, MIDX); + uint64_t step; + + check_mops_enabled(env, ra); + + /* + * We're allowed to NOP out "no data to copy" before the consistency + * checks; we choose to do so. + */ + if (setsize == 0) { + return; + } + + check_mops_wrong_option(env, syndrome, ra); + + /* + * Our implementation has no address alignment requirements, but + * we do want to enforce the "less than a page" size requirement, + * so we don't need to have the "check for interrupts" here. + */ + if (setsize >= TARGET_PAGE_SIZE) { + raise_exception_ra(env, EXCP_UDEF, syndrome, + mops_mismatch_exception_target_el(env), ra); + } + + if (!mte_checks_needed(toaddr, mtedesc)) { + mtedesc = 0; + } + + /* Do the actual memset */ + while (setsize > 0) { + step = stepfn(env, toaddr, setsize, data, memidx, &mtedesc, ra); + toaddr += step; + setsize -= step; + env->xregs[rn] = -setsize; + } +} + +void HELPER(sete)(CPUARMState *env, uint32_t syndrome, uint32_t mtedesc) +{ + do_sete(env, syndrome, mtedesc, set_step, false, GETPC()); +} diff --git a/target/arm/tcg/helper-a64.h b/target/arm/tcg/helper-a64.h index 57cfd68569..7ce5d2105a 100644 --- a/target/arm/tcg/helper-a64.h +++ b/target/arm/tcg/helper-a64.h @@ -117,3 +117,7 @@ DEF_HELPER_FLAGS_3(stzgm_tags, TCG_CALL_NO_WG, void, env, i64, i64) DEF_HELPER_FLAGS_4(unaligned_access, TCG_CALL_NO_WG, noreturn, env, i64, i32, i32) + +DEF_HELPER_3(setp, void, env, i32, i32) +DEF_HELPER_3(setm, void, env, i32, i32) +DEF_HELPER_3(sete, void, env, i32, i32) diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c index 24afd92914..bb7b15cb6c 100644 --- a/target/arm/tcg/translate-a64.c +++ b/target/arm/tcg/translate-a64.c @@ -3962,6 +3962,55 @@ TRANS_FEAT(STZG, aa64_mte_insn_reg, do_STG, a, true, false) TRANS_FEAT(ST2G, aa64_mte_insn_reg, do_STG, a, false, true) TRANS_FEAT(STZ2G, aa64_mte_insn_reg, do_STG, a, true, true) +typedef void SetFn(TCGv_env, TCGv_i32, TCGv_i32); + +static bool do_SET(DisasContext *s, arg_set *a, bool is_epilogue, SetFn fn) +{ + int memidx; + uint32_t syndrome, desc = 0; + + /* + * UNPREDICTABLE cases: we choose to UNDEF, which allows + * us to pull this check before the CheckMOPSEnabled() test + * (which we do in the helper function) + */ + if (a->rs == a->rn || a->rs == a->rd || a->rn == a->rd || + a->rd == 31 || a->rn == 31) { + return false; + } + + memidx = get_a64_user_mem_index(s, a->unpriv); + + /* + * We pass option_a == true, matching our implementation; + * we pass wrong_option == false: helper function may set that bit. + */ + syndrome = syn_mop(true, false, (a->nontemp << 1) | a->unpriv, + is_epilogue, false, true, a->rd, a->rs, a->rn); + + if (s->mte_active[a->unpriv]) { + /* We may need to do MTE tag checking, so assemble the descriptor */ + desc = FIELD_DP32(desc, MTEDESC, TBI, s->tbid); + desc = FIELD_DP32(desc, MTEDESC, TCMA, s->tcma); + desc = FIELD_DP32(desc, MTEDESC, WRITE, true); + /* SIZEM1 and ALIGN we leave 0 (byte write) */ + } + /* The helper function always needs the memidx even with MTE disabled */ + desc = FIELD_DP32(desc, MTEDESC, MIDX, memidx); + + /* + * The helper needs the register numbers, but since they're in + * the syndrome anyway, we let it extract them from there rather + * than passing in an extra three integer arguments. + */ + fn(cpu_env, tcg_constant_i32(syndrome), tcg_constant_i32(desc)); + return true; +} + +TRANS_FEAT(SETP, aa64_mops, do_SET, a, false, gen_helper_setp) +TRANS_FEAT(SETM, aa64_mops, do_SET, a, false, gen_helper_setm) +TRANS_FEAT(SETE, aa64_mops, do_SET, a, true, gen_helper_sete) + typedef void ArithTwoOp(TCGv_i64, TCGv_i64, TCGv_i64); static bool gen_rri(DisasContext *s, arg_rri_sf *a, -- 2.11.0