1 files changed, 67 insertions, 0 deletions

diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index 04f6ec1679f0..3ba102b41512 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -402,6 +402,73 @@ const struct bpf_func_proto bpf_get_stackid_proto = {
         .arg3_type      = ARG_ANYTHING,
 };
 
+BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size,
+           u64, flags)
+{
+        u32 init_nr, trace_nr, copy_len, elem_size, num_elem;
+        bool user_build_id = flags & BPF_F_USER_BUILD_ID;
+        u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
+        bool user = flags & BPF_F_USER_STACK;
+        struct perf_callchain_entry *trace;
+        bool kernel = !user;
+        int err = -EINVAL;
+        u64 *ips;
+
+        if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
+                               BPF_F_USER_BUILD_ID)))
+                goto clear;
+        if (kernel && user_build_id)
+                goto clear;
+
+        elem_size = (user && user_build_id) ? sizeof(struct bpf_stack_build_id)
+                                            : sizeof(u64);
+        if (unlikely(size % elem_size))
+                goto clear;
+
+        num_elem = size / elem_size;
+        if (sysctl_perf_event_max_stack < num_elem)
+                init_nr = 0;
+        else
+                init_nr = sysctl_perf_event_max_stack - num_elem;
+        trace = get_perf_callchain(regs, init_nr, kernel, user,
+                                   sysctl_perf_event_max_stack, false, false);
+        if (unlikely(!trace))
+                goto err_fault;
+
+        trace_nr = trace->nr - init_nr;
+        if (trace_nr < skip)
+                goto err_fault;
+
+        trace_nr -= skip;
+        trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem;
+        copy_len = trace_nr * elem_size;
+        ips = trace->ip + skip + init_nr;
+        if (user && user_build_id)
+                stack_map_get_build_id_offset(buf, ips, trace_nr, user);
+        else
+                memcpy(buf, ips, copy_len);
+
+        if (size > copy_len)
+                memset(buf + copy_len, 0, size - copy_len);
+        return copy_len;
+
+err_fault:
+        err = -EFAULT;
+clear:
+        memset(buf, 0, size);
+        return err;
+}
+
+const struct bpf_func_proto bpf_get_stack_proto = {
+        .func           = bpf_get_stack,
+        .gpl_only       = true,
+        .ret_type       = RET_INTEGER,
+        .arg1_type      = ARG_PTR_TO_CTX,
+        .arg2_type      = ARG_PTR_TO_UNINIT_MEM,
+        .arg3_type      = ARG_CONST_SIZE_OR_ZERO,
+        .arg4_type      = ARG_ANYTHING,
+};
+
 /* Called from eBPF program */
 static void *stack_map_lookup_elem(struct bpf_map *map, void *key)
 {