/* Copyright (c) 2016 Facebook * * This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License as published by the Free Software Foundation. */ #include #include "bpf_helpers.h" #include #include #include #include #define _(P) ({typeof(P) val; bpf_probe_read(&val, sizeof(val), &P); val;}) #define MINBLOCK_US 1 struct key_t { char waker[TASK_COMM_LEN]; char target[TASK_COMM_LEN]; u32 wret; u32 tret; }; struct bpf_map_def SEC("maps") counts = { .type = BPF_MAP_TYPE_HASH, .key_size = sizeof(struct key_t), .value_size = sizeof(u64), .max_entries = 10000, }; struct bpf_map_def SEC("maps") start = { .type = BPF_MAP_TYPE_HASH, .key_size = sizeof(u32), .value_size = sizeof(u64), .max_entries = 10000, }; struct wokeby_t { char name[TASK_COMM_LEN]; u32 ret; }; struct bpf_map_def SEC("maps") wokeby = { .type = BPF_MAP_TYPE_HASH, .key_size = sizeof(u32), .value_size = sizeof(struct wokeby_t), .max_entries = 10000, }; struct bpf_map_def SEC("maps") stackmap = { .type = BPF_MAP_TYPE_STACK_TRACE, .key_size = sizeof(u32), .value_size = PERF_MAX_STACK_DEPTH * sizeof(u64), .max_entries = 10000, }; #define STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP) SEC("kprobe/try_to_wake_up") int waker(struct pt_regs *ctx) { struct task_struct *p = (void *) PT_REGS_PARM1(ctx); struct wokeby_t woke; u32 pid; pid = _(p->pid); bpf_get_current_comm(&woke.name, sizeof(woke.name)); woke.ret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS); bpf_map_update_elem(&wokeby, &pid, &woke, BPF_ANY); return 0; } static inline int update_counts(void *ctx, u32 pid, u64 delta) { struct wokeby_t *woke; u64 zero = 0, *val; struct key_t key; __builtin_memset(&key.waker, 0, sizeof(key.waker)); bpf_get_current_comm(&key.target, sizeof(key.target)); key.tret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS); key.wret = 0; woke = bpf_map_lookup_elem(&wokeby, &pid); if (woke) { key.wret = woke->ret; __builtin_memcpy(&key.waker, woke->name, sizeof(key.waker)); bpf_map_delete_elem(&wokeby, &pid); } val = bpf_map_lookup_elem(&counts, &key); if (!val) { bpf_map_update_elem(&counts, &key, &zero, BPF_NOEXIST); val = bpf_map_lookup_elem(&counts, &key); if (!val) return 0; } (*val) += delta; return 0; } #if 1 /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */ struct sched_switch_args { unsigned long long pad; char prev_comm[16]; int prev_pid; int prev_prio; long long prev_state; char next_comm[16]; int next_pid; int next_prio; }; SEC("tracepoint/sched/sched_switch") int oncpu(struct sched_switch_args *ctx) { /* record previous thread sleep time */ u32 pid = ctx->prev_pid; #else SEC("kprobe/finish_task_switch") int oncpu(struct pt_regs *ctx) { struct task_struct *p = (void *) PT_REGS_PARM1(ctx); /* record previous thread sleep time */ u32 pid = _(p->pid); #endif u64 delta, ts, *tsp; ts = bpf_ktime_get_ns(); bpf_map_update_elem(&start, &pid, &ts, BPF_ANY); /* calculate current thread's delta time */ pid = bpf_get_current_pid_tgid(); tsp = bpf_map_lookup_elem(&start, &pid); if (!tsp) /* missed start or filtered */ return 0; delta = bpf_ktime_get_ns() - *tsp; bpf_map_delete_elem(&start, &pid); delta = delta / 1000; if (delta < MINBLOCK_US) return 0; return update_counts(ctx, pid, delta); } char _license[] SEC("license") = "GPL"; u32 _version SEC("version") = LINUX_VERSION_CODE; ass='list nowrap'>AgeCommit message (Expand)AuthorFilesLines 3' selected='selected'>3space:mode:
authorArd Biesheuvel <ard.biesheuvel@linaro.org>2017-02-01 17:45:02 +0000
committerIngo Molnar <mingo@kernel.org>2017-02-01 21:17:49 +0100
commitc8f325a59cfc718d13a50fbc746ed9b415c25e92 (patch)
treed53fbdac9d0781e39a13b2ac6b2bd258cf3b4140 /tools/perf/scripts/python/futex-contention.py
parentbf29bddf0417a4783da3b24e8c9e017ac649326f (diff)
efi/fdt: Avoid FDT manipulation after ExitBootServices()
Some AArch64 UEFI implementations disable the MMU in ExitBootServices(), after which unaligned accesses to RAM are no longer supported. Commit: abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel") fixed an issue in the memory map handling of the stub FDT code, but inadvertently created an issue with such firmware, by moving some of the FDT manipulation to after the invocation of ExitBootServices(). Given that the stub's libfdt implementation uses the ordinary, accelerated string functions, which rely on hardware handling of unaligned accesses, manipulating the FDT with the MMU off may result in alignment faults. So fix the situation by moving the update_fdt_memmap() call into the callback function invoked by efi_exit_boot_services() right before it calls the ExitBootServices() UEFI service (which is arguably a better place for it anyway) Note that disabling the MMU in ExitBootServices() is not compliant with the UEFI spec, and carries great risk due to the fact that switching from cached to uncached memory accesses halfway through compiler generated code (i.e., involving a stack) can never be done in a way that is architecturally safe. Fixes: abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel") Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Tested-by: Riku Voipio <riku.voipio@linaro.org> Cc: <stable@vger.kernel.org> Cc: mark.rutland@arm.com Cc: linux-efi@vger.kernel.org Cc: matt@codeblueprint.co.uk Cc: leif.lindholm@linaro.org Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1485971102-23330-2-git-send-email-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'tools/perf/scripts/python/futex-contention.py')