83 lines
1.6 KiB
C
83 lines
1.6 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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#include <stdbool.h>
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#include <errno.h>
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#include <linux/stddef.h>
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#include <linux/perf_event.h>
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#include "../../perf.h"
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#include <linux/types.h>
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#include "../../util/debug.h"
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#include "../../util/tsc.h"
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int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
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struct perf_tsc_conversion *tc)
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{
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bool cap_user_time_zero;
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u32 seq;
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int i = 0;
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while (1) {
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seq = pc->lock;
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rmb();
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tc->time_mult = pc->time_mult;
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tc->time_shift = pc->time_shift;
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tc->time_zero = pc->time_zero;
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cap_user_time_zero = pc->cap_user_time_zero;
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rmb();
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if (pc->lock == seq && !(seq & 1))
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break;
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if (++i > 10000) {
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pr_debug("failed to get perf_event_mmap_page lock\n");
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return -EINVAL;
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}
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}
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if (!cap_user_time_zero)
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return -EOPNOTSUPP;
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return 0;
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}
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u64 rdtsc(void)
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{
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unsigned int low, high;
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asm volatile("rdtsc" : "=a" (low), "=d" (high));
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return low | ((u64)high) << 32;
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}
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int perf_event__synth_time_conv(const struct perf_event_mmap_page *pc,
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struct perf_tool *tool,
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perf_event__handler_t process,
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struct machine *machine)
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{
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union perf_event event = {
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.time_conv = {
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.header = {
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.type = PERF_RECORD_TIME_CONV,
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.size = sizeof(struct time_conv_event),
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},
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},
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};
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struct perf_tsc_conversion tc;
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int err;
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if (!pc)
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return 0;
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err = perf_read_tsc_conversion(pc, &tc);
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if (err == -EOPNOTSUPP)
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return 0;
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if (err)
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return err;
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pr_debug2("Synthesizing TSC conversion information\n");
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event.time_conv.time_mult = tc.time_mult;
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event.time_conv.time_shift = tc.time_shift;
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event.time_conv.time_zero = tc.time_zero;
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return process(tool, &event, NULL, machine);
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}
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