diff options
Diffstat (limited to 'arch/riscv/kernel/cpufeature.c')
-rw-r--r-- | arch/riscv/kernel/cpufeature.c | 256 |
1 files changed, 1 insertions, 255 deletions
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index 79a5a35fab..3ed2359eae 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -11,7 +11,6 @@ #include <linux/cpu.h> #include <linux/cpuhotplug.h> #include <linux/ctype.h> -#include <linux/jump_label.h> #include <linux/log2.h> #include <linux/memory.h> #include <linux/module.h> @@ -21,21 +20,13 @@ #include <asm/cacheflush.h> #include <asm/cpufeature.h> #include <asm/hwcap.h> -#include <asm/hwprobe.h> #include <asm/patch.h> #include <asm/processor.h> #include <asm/sbi.h> #include <asm/vector.h> -#include "copy-unaligned.h" - #define NUM_ALPHA_EXTS ('z' - 'a' + 1) -#define MISALIGNED_ACCESS_JIFFIES_LG2 1 -#define MISALIGNED_BUFFER_SIZE 0x4000 -#define MISALIGNED_BUFFER_ORDER get_order(MISALIGNED_BUFFER_SIZE) -#define MISALIGNED_COPY_SIZE ((MISALIGNED_BUFFER_SIZE / 2) - 0x80) - unsigned long elf_hwcap __read_mostly; /* Host ISA bitmap */ @@ -44,11 +35,6 @@ static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly; /* Per-cpu ISA extensions. */ struct riscv_isainfo hart_isa[NR_CPUS]; -/* Performance information */ -DEFINE_PER_CPU(long, misaligned_access_speed); - -static cpumask_t fast_misaligned_access; - /** * riscv_isa_extension_base() - Get base extension word * @@ -318,6 +304,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = { __RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL), __RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT), __RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT), + __RISCV_ISA_EXT_DATA(xandespmu, RISCV_ISA_EXT_XANDESPMU), }; const size_t riscv_isa_ext_count = ARRAY_SIZE(riscv_isa_ext); @@ -731,247 +718,6 @@ unsigned long riscv_get_elf_hwcap(void) return hwcap; } -static int check_unaligned_access(void *param) -{ - int cpu = smp_processor_id(); - u64 start_cycles, end_cycles; - u64 word_cycles; - u64 byte_cycles; - int ratio; - unsigned long start_jiffies, now; - struct page *page = param; - void *dst; - void *src; - long speed = RISCV_HWPROBE_MISALIGNED_SLOW; - - if (check_unaligned_access_emulated(cpu)) - return 0; - - /* Make an unaligned destination buffer. */ - dst = (void *)((unsigned long)page_address(page) | 0x1); - /* Unalign src as well, but differently (off by 1 + 2 = 3). */ - src = dst + (MISALIGNED_BUFFER_SIZE / 2); - src += 2; - word_cycles = -1ULL; - /* Do a warmup. */ - __riscv_copy_words_unaligned(dst, src, MISALIGNED_COPY_SIZE); - preempt_disable(); - start_jiffies = jiffies; - while ((now = jiffies) == start_jiffies) - cpu_relax(); - - /* - * For a fixed amount of time, repeatedly try the function, and take - * the best time in cycles as the measurement. - */ - while (time_before(jiffies, now + (1 << MISALIGNED_ACCESS_JIFFIES_LG2))) { - start_cycles = get_cycles64(); - /* Ensure the CSR read can't reorder WRT to the copy. */ - mb(); - __riscv_copy_words_unaligned(dst, src, MISALIGNED_COPY_SIZE); - /* Ensure the copy ends before the end time is snapped. */ - mb(); - end_cycles = get_cycles64(); - if ((end_cycles - start_cycles) < word_cycles) - word_cycles = end_cycles - start_cycles; - } - - byte_cycles = -1ULL; - __riscv_copy_bytes_unaligned(dst, src, MISALIGNED_COPY_SIZE); - start_jiffies = jiffies; - while ((now = jiffies) == start_jiffies) - cpu_relax(); - - while (time_before(jiffies, now + (1 << MISALIGNED_ACCESS_JIFFIES_LG2))) { - start_cycles = get_cycles64(); - mb(); - __riscv_copy_bytes_unaligned(dst, src, MISALIGNED_COPY_SIZE); - mb(); - end_cycles = get_cycles64(); - if ((end_cycles - start_cycles) < byte_cycles) - byte_cycles = end_cycles - start_cycles; - } - - preempt_enable(); - - /* Don't divide by zero. */ - if (!word_cycles || !byte_cycles) { - pr_warn("cpu%d: rdtime lacks granularity needed to measure unaligned access speed\n", - cpu); - - return 0; - } - - if (word_cycles < byte_cycles) - speed = RISCV_HWPROBE_MISALIGNED_FAST; - - ratio = div_u64((byte_cycles * 100), word_cycles); - pr_info("cpu%d: Ratio of byte access time to unaligned word access is %d.%02d, unaligned accesses are %s\n", - cpu, - ratio / 100, - ratio % 100, - (speed == RISCV_HWPROBE_MISALIGNED_FAST) ? "fast" : "slow"); - - per_cpu(misaligned_access_speed, cpu) = speed; - - /* - * Set the value of fast_misaligned_access of a CPU. These operations - * are atomic to avoid race conditions. - */ - if (speed == RISCV_HWPROBE_MISALIGNED_FAST) - cpumask_set_cpu(cpu, &fast_misaligned_access); - else - cpumask_clear_cpu(cpu, &fast_misaligned_access); - - return 0; -} - -static void check_unaligned_access_nonboot_cpu(void *param) -{ - unsigned int cpu = smp_processor_id(); - struct page **pages = param; - - if (smp_processor_id() != 0) - check_unaligned_access(pages[cpu]); -} - -DEFINE_STATIC_KEY_FALSE(fast_misaligned_access_speed_key); - -static void modify_unaligned_access_branches(cpumask_t *mask, int weight) -{ - if (cpumask_weight(mask) == weight) - static_branch_enable_cpuslocked(&fast_misaligned_access_speed_key); - else - static_branch_disable_cpuslocked(&fast_misaligned_access_speed_key); -} - -static void set_unaligned_access_static_branches_except_cpu(int cpu) -{ - /* - * Same as set_unaligned_access_static_branches, except excludes the - * given CPU from the result. When a CPU is hotplugged into an offline - * state, this function is called before the CPU is set to offline in - * the cpumask, and thus the CPU needs to be explicitly excluded. - */ - - cpumask_t fast_except_me; - - cpumask_and(&fast_except_me, &fast_misaligned_access, cpu_online_mask); - cpumask_clear_cpu(cpu, &fast_except_me); - - modify_unaligned_access_branches(&fast_except_me, num_online_cpus() - 1); -} - -static void set_unaligned_access_static_branches(void) -{ - /* - * This will be called after check_unaligned_access_all_cpus so the - * result of unaligned access speed for all CPUs will be available. - * - * To avoid the number of online cpus changing between reading - * cpu_online_mask and calling num_online_cpus, cpus_read_lock must be - * held before calling this function. - */ - - cpumask_t fast_and_online; - - cpumask_and(&fast_and_online, &fast_misaligned_access, cpu_online_mask); - - modify_unaligned_access_branches(&fast_and_online, num_online_cpus()); -} - -static int lock_and_set_unaligned_access_static_branch(void) -{ - cpus_read_lock(); - set_unaligned_access_static_branches(); - cpus_read_unlock(); - - return 0; -} - -arch_initcall_sync(lock_and_set_unaligned_access_static_branch); - -static int riscv_online_cpu(unsigned int cpu) -{ - static struct page *buf; - - /* We are already set since the last check */ - if (per_cpu(misaligned_access_speed, cpu) != RISCV_HWPROBE_MISALIGNED_UNKNOWN) - goto exit; - - buf = alloc_pages(GFP_KERNEL, MISALIGNED_BUFFER_ORDER); - if (!buf) { - pr_warn("Allocation failure, not measuring misaligned performance\n"); - return -ENOMEM; - } - - check_unaligned_access(buf); - __free_pages(buf, MISALIGNED_BUFFER_ORDER); - -exit: - set_unaligned_access_static_branches(); - - return 0; -} - -static int riscv_offline_cpu(unsigned int cpu) -{ - set_unaligned_access_static_branches_except_cpu(cpu); - - return 0; -} - -/* Measure unaligned access on all CPUs present at boot in parallel. */ -static int check_unaligned_access_all_cpus(void) -{ - unsigned int cpu; - unsigned int cpu_count = num_possible_cpus(); - struct page **bufs = kzalloc(cpu_count * sizeof(struct page *), - GFP_KERNEL); - - if (!bufs) { - pr_warn("Allocation failure, not measuring misaligned performance\n"); - return 0; - } - - /* - * Allocate separate buffers for each CPU so there's no fighting over - * cache lines. - */ - for_each_cpu(cpu, cpu_online_mask) { - bufs[cpu] = alloc_pages(GFP_KERNEL, MISALIGNED_BUFFER_ORDER); - if (!bufs[cpu]) { - pr_warn("Allocation failure, not measuring misaligned performance\n"); - goto out; - } - } - - /* Check everybody except 0, who stays behind to tend jiffies. */ - on_each_cpu(check_unaligned_access_nonboot_cpu, bufs, 1); - - /* Check core 0. */ - smp_call_on_cpu(0, check_unaligned_access, bufs[0], true); - - /* - * Setup hotplug callbacks for any new CPUs that come online or go - * offline. - */ - cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "riscv:online", - riscv_online_cpu, riscv_offline_cpu); - -out: - unaligned_emulation_finish(); - for_each_cpu(cpu, cpu_online_mask) { - if (bufs[cpu]) - __free_pages(bufs[cpu], MISALIGNED_BUFFER_ORDER); - } - - kfree(bufs); - return 0; -} - -arch_initcall(check_unaligned_access_all_cpus); - void riscv_user_isa_enable(void) { if (riscv_cpu_has_extension_unlikely(smp_processor_id(), RISCV_ISA_EXT_ZICBOZ)) |