perf core: Pass max stack as a perf_callchain_entry context

This makes perf_callchain_{user,kernel}() receive the max stack
as context for the perf_callchain_entry, instead of accessing
the global sysctl_perf_event_max_stack.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/n/tip-kolmn1yo40p7jhswxwrc7rrd@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 14 insertions, 9 deletions

diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index f5a19548be12..a82d7605db3f 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -136,7 +136,8 @@ static u64 bpf_get_stackid(u64 r1, u64 r2, u64 flags, u64 r4, u64 r5)
                                BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
                 return -EINVAL;
 
-        trace = get_perf_callchain(regs, init_nr, kernel, user, false, false);
+        trace = get_perf_callchain(regs, init_nr, kernel, user,
+                                   sysctl_perf_event_max_stack, false, false);
 
         if (unlikely(!trace))
                 /* couldn't fetch the stack trace */
diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index 7fc89939ede9..af95ad92893a 100644
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -32,12 +32,12 @@ static DEFINE_MUTEX(callchain_mutex);
 static struct callchain_cpus_entries *callchain_cpus_entries;
 
 
-__weak void perf_callchain_kernel(struct perf_callchain_entry *entry,
+__weak void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
                                   struct pt_regs *regs)
 {
 }
 
-__weak void perf_callchain_user(struct perf_callchain_entry *entry,
+__weak void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
                                 struct pt_regs *regs)
 {
 }
@@ -176,14 +176,15 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs)
         if (!kernel && !user)
                 return NULL;
 
-        return get_perf_callchain(regs, 0, kernel, user, crosstask, true);
+        return get_perf_callchain(regs, 0, kernel, user, sysctl_perf_event_max_stack, crosstask, true);
 }
 
 struct perf_callchain_entry *
 get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
-                   bool crosstask, bool add_mark)
+                   u32 max_stack, bool crosstask, bool add_mark)
 {
         struct perf_callchain_entry *entry;
+        struct perf_callchain_entry_ctx ctx;
         int rctx;
 
         entry = get_callchain_entry(&rctx);
@@ -193,12 +194,15 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
         if (!entry)
                 goto exit_put;
 
+        ctx.entry     = entry;
+        ctx.max_stack = max_stack;
+
         entry->nr = init_nr;
 
         if (kernel && !user_mode(regs)) {
                 if (add_mark)
-                        perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
-                perf_callchain_kernel(entry, regs);
+                        perf_callchain_store(&ctx, PERF_CONTEXT_KERNEL);
+                perf_callchain_kernel(&ctx, regs);
         }
 
         if (user) {
@@ -214,8 +218,8 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
                                 goto exit_put;
 
                         if (add_mark)
-                                perf_callchain_store(entry, PERF_CONTEXT_USER);
-                        perf_callchain_user(entry, regs);
+                                perf_callchain_store(&ctx, PERF_CONTEXT_USER);
+                        perf_callchain_user(&ctx, regs);
                 }
         }