4 files changed, 140 insertions, 1 deletions

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index ba03ec39efb3..9349a5db3cf2 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -31,6 +31,7 @@
 #include <linux/rbtree_latch.h>
 #include <linux/kallsyms.h>
 #include <linux/rcupdate.h>
+#include <linux/perf_event.h>
 
 #include <asm/unaligned.h>
 
@@ -1722,6 +1723,10 @@ static void bpf_prog_free_deferred(struct work_struct *work)
 	aux = container_of(work, struct bpf_prog_aux, work);
 	if (bpf_prog_is_dev_bound(aux))
 		bpf_prog_offload_destroy(aux->prog);
+#ifdef CONFIG_PERF_EVENTS
+	if (aux->prog->has_callchain_buf)
+		put_callchain_buffers();
+#endif
 	for (i = 0; i < aux->func_cnt; i++)
 		bpf_jit_free(aux->func[i]);
 	if (aux->func_cnt) {
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)
 {
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index eb1a596aebd3..253f6bdb9117 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -22,6 +22,7 @@
 #include <linux/stringify.h>
 #include <linux/bsearch.h>
 #include <linux/sort.h>
+#include <linux/perf_event.h>
 
 #include "disasm.h"
 
@@ -2450,6 +2451,24 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
 	if (err)
 		return err;
 
+	if (func_id == BPF_FUNC_get_stack && !env->prog->has_callchain_buf) {
+		const char *err_str;
+
+#ifdef CONFIG_PERF_EVENTS
+		err = get_callchain_buffers(sysctl_perf_event_max_stack);
+		err_str = "cannot get callchain buffer for func %s#%d\n";
+#else
+		err = -ENOTSUPP;
+		err_str = "func %s#%d not supported without CONFIG_PERF_EVENTS\n";
+#endif
+		if (err) {
+			verbose(env, err_str, func_id_name(func_id), func_id);
+			return err;
+		}
+
+		env->prog->has_callchain_buf = true;
+	}
+
 	if (changes_data)
 		clear_all_pkt_pointers(env);
 	return 0;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 56ba0f2a01db..46d866e9937c 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -20,6 +20,7 @@
 #include "trace.h"
 
 u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
+u64 bpf_get_stack(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 
 /**
  * trace_call_bpf - invoke BPF program
@@ -577,6 +578,8 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_perf_event_output_proto;
 	case BPF_FUNC_get_stackid:
 		return &bpf_get_stackid_proto;
+	case BPF_FUNC_get_stack:
+		return &bpf_get_stack_proto;
 	case BPF_FUNC_perf_event_read_value:
 		return &bpf_perf_event_read_value_proto;
 #ifdef CONFIG_BPF_KPROBE_OVERRIDE
@@ -664,6 +667,25 @@ static const struct bpf_func_proto bpf_get_stackid_proto_tp = {
 	.arg3_type	= ARG_ANYTHING,
 };
 
+BPF_CALL_4(bpf_get_stack_tp, void *, tp_buff, void *, buf, u32, size,
+	   u64, flags)
+{
+	struct pt_regs *regs = *(struct pt_regs **)tp_buff;
+
+	return bpf_get_stack((unsigned long) regs, (unsigned long) buf,
+			     (unsigned long) size, flags, 0);
+}
+
+static const struct bpf_func_proto bpf_get_stack_proto_tp = {
+	.func		= bpf_get_stack_tp,
+	.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,
+};
+
 static const struct bpf_func_proto *
 tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {
@@ -672,6 +694,8 @@ tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_perf_event_output_proto_tp;
 	case BPF_FUNC_get_stackid:
 		return &bpf_get_stackid_proto_tp;
+	case BPF_FUNC_get_stack:
+		return &bpf_get_stack_proto_tp;
 	default:
 		return tracing_func_proto(func_id, prog);
 	}
@@ -734,6 +758,8 @@ pe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_perf_event_output_proto_tp;
 	case BPF_FUNC_get_stackid:
 		return &bpf_get_stackid_proto_tp;
+	case BPF_FUNC_get_stack:
+		return &bpf_get_stack_proto_tp;
 	case BPF_FUNC_perf_prog_read_value:
 		return &bpf_perf_prog_read_value_proto;
 	default:
@@ -744,7 +770,7 @@ pe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 /*
  * bpf_raw_tp_regs are separate from bpf_pt_regs used from skb/xdp
  * to avoid potential recursive reuse issue when/if tracepoints are added
- * inside bpf_*_event_output and/or bpf_get_stack_id
+ * inside bpf_*_event_output, bpf_get_stackid and/or bpf_get_stack
  */
 static DEFINE_PER_CPU(struct pt_regs, bpf_raw_tp_regs);
 BPF_CALL_5(bpf_perf_event_output_raw_tp, struct bpf_raw_tracepoint_args *, args,
@@ -787,6 +813,26 @@ static const struct bpf_func_proto bpf_get_stackid_proto_raw_tp = {
 	.arg3_type	= ARG_ANYTHING,
 };
 
+BPF_CALL_4(bpf_get_stack_raw_tp, struct bpf_raw_tracepoint_args *, args,
+	   void *, buf, u32, size, u64, flags)
+{
+	struct pt_regs *regs = this_cpu_ptr(&bpf_raw_tp_regs);
+
+	perf_fetch_caller_regs(regs);
+	return bpf_get_stack((unsigned long) regs, (unsigned long) buf,
+			     (unsigned long) size, flags, 0);
+}
+
+static const struct bpf_func_proto bpf_get_stack_proto_raw_tp = {
+	.func		= bpf_get_stack_raw_tp,
+	.gpl_only	= true,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
+	.arg4_type	= ARG_ANYTHING,
+};
+
 static const struct bpf_func_proto *
 raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {
@@ -795,6 +841,8 @@ raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_perf_event_output_proto_raw_tp;
 	case BPF_FUNC_get_stackid:
 		return &bpf_get_stackid_proto_raw_tp;
+	case BPF_FUNC_get_stack:
+		return &bpf_get_stack_proto_raw_tp;
 	default:
 		return tracing_func_proto(func_id, prog);
 	}