summaryrefslogtreecommitdiff
path: root/kernel/trace/bpf_trace.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/trace/bpf_trace.c')
-rw-r--r--kernel/trace/bpf_trace.c526
1 files changed, 472 insertions, 54 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 3dd40c736067..3f49c99bc0e0 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1,4 +1,5 @@
/* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com
+ * 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
@@ -8,16 +9,15 @@
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/bpf.h>
+#include <linux/bpf_perf_event.h>
#include <linux/filter.h>
#include <linux/uaccess.h>
#include <linux/ctype.h>
#include "trace.h"
-static DEFINE_PER_CPU(int, bpf_prog_active);
-
/**
* trace_call_bpf - invoke BPF program
- * @prog: BPF program
+ * @call: tracepoint event
* @ctx: opaque context pointer
*
* kprobe handlers execute BPF programs via this helper.
@@ -29,7 +29,7 @@ static DEFINE_PER_CPU(int, bpf_prog_active);
* 1 - store kprobe event into ring buffer
* Other values are reserved and currently alias to 1
*/
-unsigned int trace_call_bpf(struct bpf_prog *prog, void *ctx)
+unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx)
{
unsigned int ret;
@@ -49,9 +49,22 @@ unsigned int trace_call_bpf(struct bpf_prog *prog, void *ctx)
goto out;
}
- rcu_read_lock();
- ret = BPF_PROG_RUN(prog, ctx);
- rcu_read_unlock();
+ /*
+ * Instead of moving rcu_read_lock/rcu_dereference/rcu_read_unlock
+ * to all call sites, we did a bpf_prog_array_valid() there to check
+ * whether call->prog_array is empty or not, which is
+ * a heurisitc to speed up execution.
+ *
+ * If bpf_prog_array_valid() fetched prog_array was
+ * non-NULL, we go into trace_call_bpf() and do the actual
+ * proper rcu_dereference() under RCU lock.
+ * If it turns out that prog_array is NULL then, we bail out.
+ * For the opposite, if the bpf_prog_array_valid() fetched pointer
+ * was NULL, you'll skip the prog_array with the risk of missing
+ * out of events when it was updated in between this and the
+ * rcu_dereference() which is accepted risk.
+ */
+ ret = BPF_PROG_RUN_ARRAY_CHECK(call->prog_array, ctx, BPF_PROG_RUN);
out:
__this_cpu_dec(bpf_prog_active);
@@ -61,35 +74,106 @@ unsigned int trace_call_bpf(struct bpf_prog *prog, void *ctx)
}
EXPORT_SYMBOL_GPL(trace_call_bpf);
-static u64 bpf_probe_read(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr)
{
- void *dst = (void *) (long) r1;
- int size = (int) r2;
- void *unsafe_ptr = (void *) (long) r3;
+ int ret;
- return probe_kernel_read(dst, unsafe_ptr, size);
+ ret = probe_kernel_read(dst, unsafe_ptr, size);
+ if (unlikely(ret < 0))
+ memset(dst, 0, size);
+
+ return ret;
}
static const struct bpf_func_proto bpf_probe_read_proto = {
.func = bpf_probe_read,
.gpl_only = true,
.ret_type = RET_INTEGER,
- .arg1_type = ARG_PTR_TO_STACK,
+ .arg1_type = ARG_PTR_TO_RAW_STACK,
.arg2_type = ARG_CONST_STACK_SIZE,
.arg3_type = ARG_ANYTHING,
};
+BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size, const void *, unsafe_ptr)
+{
+ int ret;
+
+ /*
+ * The strncpy_from_unsafe() call will likely not fill the entire
+ * buffer, but that's okay in this circumstance as we're probing
+ * arbitrary memory anyway similar to bpf_probe_read() and might
+ * as well probe the stack. Thus, memory is explicitly cleared
+ * only in error case, so that improper users ignoring return
+ * code altogether don't copy garbage; otherwise length of string
+ * is returned that can be used for bpf_perf_event_output() et al.
+ */
+ ret = strncpy_from_unsafe(dst, unsafe_ptr, size);
+ if (unlikely(ret < 0))
+ memset(dst, 0, size);
+
+ return ret;
+}
+
+static const struct bpf_func_proto bpf_probe_read_str_proto = {
+ .func = bpf_probe_read_str,
+ .gpl_only = true,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_RAW_STACK,
+ .arg2_type = ARG_CONST_STACK_SIZE,
+ .arg3_type = ARG_ANYTHING,
+};
+
+BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src,
+ u32, size)
+{
+ /*
+ * Ensure we're in user context which is safe for the helper to
+ * run. This helper has no business in a kthread.
+ *
+ * access_ok() should prevent writing to non-user memory, but in
+ * some situations (nommu, temporary switch, etc) access_ok() does
+ * not provide enough validation, hence the check on KERNEL_DS.
+ */
+
+ if (unlikely(in_interrupt() ||
+ current->flags & (PF_KTHREAD | PF_EXITING)))
+ return -EPERM;
+ if (unlikely(segment_eq(get_fs(), KERNEL_DS)))
+ return -EPERM;
+ if (!access_ok(VERIFY_WRITE, unsafe_ptr, size))
+ return -EPERM;
+
+ return probe_kernel_write(unsafe_ptr, src, size);
+}
+
+static const struct bpf_func_proto bpf_probe_write_user_proto = {
+ .func = bpf_probe_write_user,
+ .gpl_only = true,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_ANYTHING,
+ .arg2_type = ARG_PTR_TO_STACK,
+ .arg3_type = ARG_CONST_STACK_SIZE,
+};
+
+static const struct bpf_func_proto *bpf_get_probe_write_proto(void)
+{
+ pr_warn_ratelimited("%s[%d] is installing a program with bpf_probe_write_user helper that may corrupt user memory!",
+ current->comm, task_pid_nr(current));
+
+ return &bpf_probe_write_user_proto;
+}
+
/*
* limited trace_printk()
* only %d %u %x %ld %lu %lx %lld %llu %llx %p %s conversion specifiers allowed
*/
-static u64 bpf_trace_printk(u64 r1, u64 fmt_size, u64 r3, u64 r4, u64 r5)
+BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
+ u64, arg2, u64, arg3)
{
- char *fmt = (char *) (long) r1;
bool str_seen = false;
int mod[3] = {};
int fmt_cnt = 0;
- u64 unsafe_addr;
+ u64 unsafe_addr = 0;
char buf[64];
int i;
@@ -133,16 +217,16 @@ static u64 bpf_trace_printk(u64 r1, u64 fmt_size, u64 r3, u64 r4, u64 r5)
switch (fmt_cnt) {
case 1:
- unsafe_addr = r3;
- r3 = (long) buf;
+ unsafe_addr = arg1;
+ arg1 = (long) buf;
break;
case 2:
- unsafe_addr = r4;
- r4 = (long) buf;
+ unsafe_addr = arg2;
+ arg2 = (long) buf;
break;
case 3:
- unsafe_addr = r5;
- r5 = (long) buf;
+ unsafe_addr = arg3;
+ arg3 = (long) buf;
break;
}
buf[0] = 0;
@@ -163,10 +247,36 @@ static u64 bpf_trace_printk(u64 r1, u64 fmt_size, u64 r3, u64 r4, u64 r5)
fmt_cnt++;
}
- return __trace_printk(1/* fake ip will not be printed */, fmt,
- mod[0] == 2 ? r3 : mod[0] == 1 ? (long) r3 : (u32) r3,
- mod[1] == 2 ? r4 : mod[1] == 1 ? (long) r4 : (u32) r4,
- mod[2] == 2 ? r5 : mod[2] == 1 ? (long) r5 : (u32) r5);
+/* Horrid workaround for getting va_list handling working with different
+ * argument type combinations generically for 32 and 64 bit archs.
+ */
+#define __BPF_TP_EMIT() __BPF_ARG3_TP()
+#define __BPF_TP(...) \
+ __trace_printk(1 /* Fake ip will not be printed. */, \
+ fmt, ##__VA_ARGS__)
+
+#define __BPF_ARG1_TP(...) \
+ ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64)) \
+ ? __BPF_TP(arg1, ##__VA_ARGS__) \
+ : ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32)) \
+ ? __BPF_TP((long)arg1, ##__VA_ARGS__) \
+ : __BPF_TP((u32)arg1, ##__VA_ARGS__)))
+
+#define __BPF_ARG2_TP(...) \
+ ((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64)) \
+ ? __BPF_ARG1_TP(arg2, ##__VA_ARGS__) \
+ : ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32)) \
+ ? __BPF_ARG1_TP((long)arg2, ##__VA_ARGS__) \
+ : __BPF_ARG1_TP((u32)arg2, ##__VA_ARGS__)))
+
+#define __BPF_ARG3_TP(...) \
+ ((mod[2] == 2 || (mod[2] == 1 && __BITS_PER_LONG == 64)) \
+ ? __BPF_ARG2_TP(arg3, ##__VA_ARGS__) \
+ : ((mod[2] == 1 || (mod[2] == 0 && __BITS_PER_LONG == 32)) \
+ ? __BPF_ARG2_TP((long)arg3, ##__VA_ARGS__) \
+ : __BPF_ARG2_TP((u32)arg3, ##__VA_ARGS__)))
+
+ return __BPF_TP_EMIT();
}
static const struct bpf_func_proto bpf_trace_printk_proto = {
@@ -188,22 +298,36 @@ const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
return &bpf_trace_printk_proto;
}
-static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
+BPF_CALL_2(bpf_perf_event_read, struct bpf_map *, map, u64, flags)
{
- struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
struct bpf_array *array = container_of(map, struct bpf_array, map);
+ unsigned int cpu = smp_processor_id();
+ u64 index = flags & BPF_F_INDEX_MASK;
+ struct bpf_event_entry *ee;
struct perf_event *event;
+ if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
+ return -EINVAL;
+ if (index == BPF_F_CURRENT_CPU)
+ index = cpu;
if (unlikely(index >= array->map.max_entries))
return -E2BIG;
- event = (struct perf_event *)array->ptrs[index];
- if (!event)
+ ee = READ_ONCE(array->ptrs[index]);
+ if (!ee)
return -ENOENT;
+ event = ee->event;
+ if (unlikely(event->attr.type != PERF_TYPE_HARDWARE &&
+ event->attr.type != PERF_TYPE_RAW))
+ return -EINVAL;
+
/* make sure event is local and doesn't have pmu::count */
- if (event->oncpu != smp_processor_id() ||
- event->pmu->count)
+ if (unlikely(event->oncpu != cpu || event->pmu->count))
+ return -EINVAL;
+
+ if (unlikely(event->attr.type != PERF_TYPE_HARDWARE &&
+ event->attr.type != PERF_TYPE_RAW))
return -EINVAL;
/*
@@ -222,39 +346,56 @@ static const struct bpf_func_proto bpf_perf_event_read_proto = {
.arg2_type = ARG_ANYTHING,
};
-static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 index, u64 r4, u64 size)
+static __always_inline u64
+__bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map,
+ u64 flags, struct perf_raw_record *raw)
{
- struct pt_regs *regs = (struct pt_regs *) (long) r1;
- struct bpf_map *map = (struct bpf_map *) (long) r2;
struct bpf_array *array = container_of(map, struct bpf_array, map);
- void *data = (void *) (long) r4;
+ unsigned int cpu = smp_processor_id();
+ u64 index = flags & BPF_F_INDEX_MASK;
struct perf_sample_data sample_data;
+ struct bpf_event_entry *ee;
struct perf_event *event;
- struct perf_raw_record raw = {
- .size = size,
- .data = data,
- };
+ if (index == BPF_F_CURRENT_CPU)
+ index = cpu;
if (unlikely(index >= array->map.max_entries))
return -E2BIG;
- event = (struct perf_event *)array->ptrs[index];
- if (unlikely(!event))
+ ee = READ_ONCE(array->ptrs[index]);
+ if (!ee)
return -ENOENT;
+ event = ee->event;
if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE ||
event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
return -EINVAL;
- if (unlikely(event->oncpu != smp_processor_id()))
+ if (unlikely(event->oncpu != cpu))
return -EOPNOTSUPP;
perf_sample_data_init(&sample_data, 0, 0);
- sample_data.raw = &raw;
+ sample_data.raw = raw;
perf_event_output(event, &sample_data, regs);
return 0;
}
+BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map,
+ u64, flags, void *, data, u64, size)
+{
+ struct perf_raw_record raw = {
+ .frag = {
+ .size = size,
+ .data = data,
+ },
+ };
+
+ if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
+ return -EINVAL;
+
+ return __bpf_perf_event_output(regs, map, flags, &raw);
+}
+
static const struct bpf_func_proto bpf_perf_event_output_proto = {
.func = bpf_perf_event_output,
.gpl_only = true,
@@ -266,7 +407,69 @@ static const struct bpf_func_proto bpf_perf_event_output_proto = {
.arg5_type = ARG_CONST_STACK_SIZE,
};
-static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id)
+static DEFINE_PER_CPU(struct pt_regs, bpf_pt_regs);
+
+u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
+ void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy)
+{
+ struct pt_regs *regs = this_cpu_ptr(&bpf_pt_regs);
+ struct perf_raw_frag frag = {
+ .copy = ctx_copy,
+ .size = ctx_size,
+ .data = ctx,
+ };
+ struct perf_raw_record raw = {
+ .frag = {
+ {
+ .next = ctx_size ? &frag : NULL,
+ },
+ .size = meta_size,
+ .data = meta,
+ },
+ };
+
+ perf_fetch_caller_regs(regs);
+
+ return __bpf_perf_event_output(regs, map, flags, &raw);
+}
+
+BPF_CALL_0(bpf_get_current_task)
+{
+ return (long) current;
+}
+
+static const struct bpf_func_proto bpf_get_current_task_proto = {
+ .func = bpf_get_current_task,
+ .gpl_only = true,
+ .ret_type = RET_INTEGER,
+};
+
+BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
+{
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
+ struct cgroup *cgrp;
+
+ if (unlikely(in_interrupt()))
+ return -EINVAL;
+ if (unlikely(idx >= array->map.max_entries))
+ return -E2BIG;
+
+ cgrp = READ_ONCE(array->ptrs[idx]);
+ if (unlikely(!cgrp))
+ return -EAGAIN;
+
+ return task_under_cgroup_hierarchy(current, cgrp);
+}
+
+static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
+ .func = bpf_current_task_under_cgroup,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_CONST_MAP_PTR,
+ .arg2_type = ARG_ANYTHING,
+};
+
+static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id)
{
switch (func_id) {
case BPF_FUNC_map_lookup_elem:
@@ -277,12 +480,16 @@ static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func
return &bpf_map_delete_elem_proto;
case BPF_FUNC_probe_read:
return &bpf_probe_read_proto;
+ case BPF_FUNC_probe_read_str:
+ return &bpf_probe_read_str_proto;
case BPF_FUNC_ktime_get_ns:
return &bpf_ktime_get_ns_proto;
case BPF_FUNC_tail_call:
return &bpf_tail_call_proto;
case BPF_FUNC_get_current_pid_tgid:
return &bpf_get_current_pid_tgid_proto;
+ case BPF_FUNC_get_current_task:
+ return &bpf_get_current_task_proto;
case BPF_FUNC_get_current_uid_gid:
return &bpf_get_current_uid_gid_proto;
case BPF_FUNC_get_current_comm:
@@ -293,32 +500,43 @@ static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func
return &bpf_get_smp_processor_id_proto;
case BPF_FUNC_perf_event_read:
return &bpf_perf_event_read_proto;
+ case BPF_FUNC_probe_write_user:
+ return bpf_get_probe_write_proto();
+ case BPF_FUNC_current_task_under_cgroup:
+ return &bpf_current_task_under_cgroup_proto;
+ case BPF_FUNC_get_prandom_u32:
+ return &bpf_get_prandom_u32_proto;
+ default:
+ return NULL;
+ }
+}
+
+static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id)
+{
+ switch (func_id) {
case BPF_FUNC_perf_event_output:
return &bpf_perf_event_output_proto;
+ case BPF_FUNC_get_stackid:
+ return &bpf_get_stackid_proto;
default:
- return NULL;
+ return tracing_func_proto(func_id);
}
}
/* bpf+kprobe programs can access fields of 'struct pt_regs' */
-static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type)
+static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
+ enum bpf_reg_type *reg_type)
{
- /* check bounds */
if (off < 0 || off >= sizeof(struct pt_regs))
return false;
-
- /* only read is allowed */
if (type != BPF_READ)
return false;
-
- /* disallow misaligned access */
if (off % size != 0)
return false;
-
return true;
}
-static struct bpf_verifier_ops kprobe_prog_ops = {
+static const struct bpf_verifier_ops kprobe_prog_ops = {
.get_func_proto = kprobe_prog_func_proto,
.is_valid_access = kprobe_prog_is_valid_access,
};
@@ -328,9 +546,209 @@ static struct bpf_prog_type_list kprobe_tl = {
.type = BPF_PROG_TYPE_KPROBE,
};
+BPF_CALL_5(bpf_perf_event_output_tp, void *, tp_buff, struct bpf_map *, map,
+ u64, flags, void *, data, u64, size)
+{
+ struct pt_regs *regs = *(struct pt_regs **)tp_buff;
+
+ /*
+ * r1 points to perf tracepoint buffer where first 8 bytes are hidden
+ * from bpf program and contain a pointer to 'struct pt_regs'. Fetch it
+ * from there and call the same bpf_perf_event_output() helper inline.
+ */
+ return ____bpf_perf_event_output(regs, map, flags, data, size);
+}
+
+static const struct bpf_func_proto bpf_perf_event_output_proto_tp = {
+ .func = bpf_perf_event_output_tp,
+ .gpl_only = true,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_CONST_MAP_PTR,
+ .arg3_type = ARG_ANYTHING,
+ .arg4_type = ARG_PTR_TO_STACK,
+ .arg5_type = ARG_CONST_STACK_SIZE,
+};
+
+BPF_CALL_3(bpf_get_stackid_tp, void *, tp_buff, struct bpf_map *, map,
+ u64, flags)
+{
+ struct pt_regs *regs = *(struct pt_regs **)tp_buff;
+
+ /*
+ * Same comment as in bpf_perf_event_output_tp(), only that this time
+ * the other helper's function body cannot be inlined due to being
+ * external, thus we need to call raw helper function.
+ */
+ return bpf_get_stackid((unsigned long) regs, (unsigned long) map,
+ flags, 0, 0);
+}
+
+static const struct bpf_func_proto bpf_get_stackid_proto_tp = {
+ .func = bpf_get_stackid_tp,
+ .gpl_only = true,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_CONST_MAP_PTR,
+ .arg3_type = ARG_ANYTHING,
+};
+
+static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id)
+{
+ switch (func_id) {
+ case BPF_FUNC_perf_event_output:
+ return &bpf_perf_event_output_proto_tp;
+ case BPF_FUNC_get_stackid:
+ return &bpf_get_stackid_proto_tp;
+ default:
+ return tracing_func_proto(func_id);
+ }
+}
+
+static bool tp_prog_is_valid_access(int off, int size, enum bpf_access_type type,
+ enum bpf_reg_type *reg_type)
+{
+ if (off < sizeof(void *) || off >= PERF_MAX_TRACE_SIZE)
+ return false;
+ if (type != BPF_READ)
+ return false;
+ if (off % size != 0)
+ return false;
+ return true;
+}
+
+static const struct bpf_verifier_ops tracepoint_prog_ops = {
+ .get_func_proto = tp_prog_func_proto,
+ .is_valid_access = tp_prog_is_valid_access,
+};
+
+static struct bpf_prog_type_list tracepoint_tl = {
+ .ops = &tracepoint_prog_ops,
+ .type = BPF_PROG_TYPE_TRACEPOINT,
+};
+
+static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
+ enum bpf_reg_type *reg_type)
+{
+ if (off < 0 || off >= sizeof(struct bpf_perf_event_data))
+ return false;
+ if (type != BPF_READ)
+ return false;
+ if (off % size != 0)
+ return false;
+ if (off == offsetof(struct bpf_perf_event_data, sample_period)) {
+ if (size != sizeof(u64))
+ return false;
+ } else {
+ if (size != sizeof(long))
+ return false;
+ }
+ return true;
+}
+
+static u32 pe_prog_convert_ctx_access(enum bpf_access_type type, int dst_reg,
+ int src_reg, int ctx_off,
+ struct bpf_insn *insn_buf,
+ struct bpf_prog *prog)
+{
+ struct bpf_insn *insn = insn_buf;
+
+ switch (ctx_off) {
+ case offsetof(struct bpf_perf_event_data, sample_period):
+ BUILD_BUG_ON(FIELD_SIZEOF(struct perf_sample_data, period) != sizeof(u64));
+
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
+ data), dst_reg, src_reg,
+ offsetof(struct bpf_perf_event_data_kern, data));
+ *insn++ = BPF_LDX_MEM(BPF_DW, dst_reg, dst_reg,
+ offsetof(struct perf_sample_data, period));
+ break;
+ default:
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
+ regs), dst_reg, src_reg,
+ offsetof(struct bpf_perf_event_data_kern, regs));
+ *insn++ = BPF_LDX_MEM(BPF_SIZEOF(long), dst_reg, dst_reg, ctx_off);
+ break;
+ }
+
+ return insn - insn_buf;
+}
+
+static const struct bpf_verifier_ops perf_event_prog_ops = {
+ .get_func_proto = tp_prog_func_proto,
+ .is_valid_access = pe_prog_is_valid_access,
+ .convert_ctx_access = pe_prog_convert_ctx_access,
+};
+
+static DEFINE_MUTEX(bpf_event_mutex);
+
+int perf_event_attach_bpf_prog(struct perf_event *event,
+ struct bpf_prog *prog)
+{
+ struct bpf_prog_array __rcu *old_array;
+ struct bpf_prog_array *new_array;
+ int ret = -EEXIST;
+
+ mutex_lock(&bpf_event_mutex);
+
+ if (event->prog)
+ goto out;
+
+ old_array = rcu_dereference_protected(event->tp_event->prog_array,
+ lockdep_is_held(&bpf_event_mutex));
+ ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
+ if (ret < 0)
+ goto out;
+
+ /* set the new array to event->tp_event and set event->prog */
+ event->prog = prog;
+ rcu_assign_pointer(event->tp_event->prog_array, new_array);
+ bpf_prog_array_free(old_array);
+
+out:
+ mutex_unlock(&bpf_event_mutex);
+ return ret;
+}
+
+void perf_event_detach_bpf_prog(struct perf_event *event)
+{
+ struct bpf_prog_array __rcu *old_array;
+ struct bpf_prog_array *new_array;
+ int ret;
+
+ mutex_lock(&bpf_event_mutex);
+
+ if (!event->prog)
+ goto out;
+
+ old_array = rcu_dereference_protected(event->tp_event->prog_array,
+ lockdep_is_held(&bpf_event_mutex));
+
+ ret = bpf_prog_array_copy(old_array, event->prog, NULL, &new_array);
+ if (ret < 0) {
+ bpf_prog_array_delete_safe(old_array, event->prog);
+ } else {
+ rcu_assign_pointer(event->tp_event->prog_array, new_array);
+ bpf_prog_array_free(old_array);
+ }
+
+ bpf_prog_put(event->prog);
+ event->prog = NULL;
+
+out:
+ mutex_unlock(&bpf_event_mutex);
+}
+
+static struct bpf_prog_type_list perf_event_tl = {
+ .ops = &perf_event_prog_ops,
+ .type = BPF_PROG_TYPE_PERF_EVENT,
+};
+
static int __init register_kprobe_prog_ops(void)
{
bpf_register_prog_type(&kprobe_tl);
+ bpf_register_prog_type(&tracepoint_tl);
+ bpf_register_prog_type(&perf_event_tl);
return 0;
}
late_initcall(register_kprobe_prog_ops);