From e26d0d226892f67435cadcce86df0ddfb9943174 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Thu, 25 Jun 2020 20:31:16 -0700 Subject: [PATCH] target/arm: Simplify DC_ZVA Now that we know that the operation is on a single page, we need not loop over pages while probing. Reviewed-by: Peter Maydell Signed-off-by: Richard Henderson Message-id: 20200626033144.790098-19-richard.henderson@linaro.org Signed-off-by: Peter Maydell --- target/arm/helper-a64.c | 94 +++++++++++------------------------------ 1 file changed, 25 insertions(+), 69 deletions(-) diff --git a/target/arm/helper-a64.c b/target/arm/helper-a64.c index bc0649a44a..8682630ff6 100644 --- a/target/arm/helper-a64.c +++ b/target/arm/helper-a64.c @@ -1119,85 +1119,41 @@ void HELPER(dc_zva)(CPUARMState *env, uint64_t vaddr_in) * (which matches the usual QEMU behaviour of not implementing either * alignment faults or any memory attribute handling). */ - - ARMCPU *cpu = env_archcpu(env); - uint64_t blocklen = 4 << cpu->dcz_blocksize; + int blocklen = 4 << env_archcpu(env)->dcz_blocksize; uint64_t vaddr = vaddr_in & ~(blocklen - 1); + int mmu_idx = cpu_mmu_index(env, false); + void *mem; + + /* + * Trapless lookup. In addition to actual invalid page, may + * return NULL for I/O, watchpoints, clean pages, etc. + */ + mem = tlb_vaddr_to_host(env, vaddr, MMU_DATA_STORE, mmu_idx); #ifndef CONFIG_USER_ONLY - { + if (unlikely(!mem)) { + uintptr_t ra = GETPC(); + /* - * Slightly awkwardly, QEMU's TARGET_PAGE_SIZE may be less than - * the block size so we might have to do more than one TLB lookup. - * We know that in fact for any v8 CPU the page size is at least 4K - * and the block size must be 2K or less, but TARGET_PAGE_SIZE is only - * 1K as an artefact of legacy v5 subpage support being present in the - * same QEMU executable. So in practice the hostaddr[] array has - * two entries, given the current setting of TARGET_PAGE_BITS_MIN. + * Trap if accessing an invalid page. DC_ZVA requires that we supply + * the original pointer for an invalid page. But watchpoints require + * that we probe the actual space. So do both. */ - int maxidx = DIV_ROUND_UP(blocklen, TARGET_PAGE_SIZE); - void *hostaddr[DIV_ROUND_UP(2 * KiB, 1 << TARGET_PAGE_BITS_MIN)]; - int try, i; - unsigned mmu_idx = cpu_mmu_index(env, false); - TCGMemOpIdx oi = make_memop_idx(MO_UB, mmu_idx); + (void) probe_write(env, vaddr_in, 1, mmu_idx, ra); + mem = probe_write(env, vaddr, blocklen, mmu_idx, ra); - assert(maxidx <= ARRAY_SIZE(hostaddr)); - - for (try = 0; try < 2; try++) { - - for (i = 0; i < maxidx; i++) { - hostaddr[i] = tlb_vaddr_to_host(env, - vaddr + TARGET_PAGE_SIZE * i, - 1, mmu_idx); - if (!hostaddr[i]) { - break; - } - } - if (i == maxidx) { - /* - * If it's all in the TLB it's fair game for just writing to; - * we know we don't need to update dirty status, etc. - */ - for (i = 0; i < maxidx - 1; i++) { - memset(hostaddr[i], 0, TARGET_PAGE_SIZE); - } - memset(hostaddr[i], 0, blocklen - (i * TARGET_PAGE_SIZE)); - return; - } + if (unlikely(!mem)) { /* - * OK, try a store and see if we can populate the tlb. This - * might cause an exception if the memory isn't writable, - * in which case we will longjmp out of here. We must for - * this purpose use the actual register value passed to us - * so that we get the fault address right. + * The only remaining reason for mem == NULL is I/O. + * Just do a series of byte writes as the architecture demands. */ - helper_ret_stb_mmu(env, vaddr_in, 0, oi, GETPC()); - /* Now we can populate the other TLB entries, if any */ - for (i = 0; i < maxidx; i++) { - uint64_t va = vaddr + TARGET_PAGE_SIZE * i; - if (va != (vaddr_in & TARGET_PAGE_MASK)) { - helper_ret_stb_mmu(env, va, 0, oi, GETPC()); - } + for (int i = 0; i < blocklen; i++) { + cpu_stb_mmuidx_ra(env, vaddr + i, 0, mmu_idx, ra); } - } - - /* - * Slow path (probably attempt to do this to an I/O device or - * similar, or clearing of a block of code we have translations - * cached for). Just do a series of byte writes as the architecture - * demands. It's not worth trying to use a cpu_physical_memory_map(), - * memset(), unmap() sequence here because: - * + we'd need to account for the blocksize being larger than a page - * + the direct-RAM access case is almost always going to be dealt - * with in the fastpath code above, so there's no speed benefit - * + we would have to deal with the map returning NULL because the - * bounce buffer was in use - */ - for (i = 0; i < blocklen; i++) { - helper_ret_stb_mmu(env, vaddr + i, 0, oi, GETPC()); + return; } } -#else - memset(g2h(vaddr), 0, blocklen); #endif + + memset(mem, 0, blocklen); }