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From: Adrian Hunter <adrian.hunter@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>, Andi Kleen <ak@linux.intel.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Joerg Roedel <joro@8bytes.org>, Jiri Olsa <jolsa@redhat.com>,
	linux-kernel@vger.kernel.org, x86@kernel.org
Subject: [PATCH V2 09/20] perf tools: Fix map_groups__split_kallsyms() for entry trampoline symbols
Date: Thu, 17 May 2018 12:21:57 +0300	[thread overview]
Message-ID: <1526548928-20790-10-git-send-email-adrian.hunter@intel.com> (raw)
In-Reply-To: <1526548928-20790-1-git-send-email-adrian.hunter@intel.com>

When kernel symbols are derived from /proc/kallsyms only (not using vmlinux
or /proc/kcore) map_groups__split_kallsyms() is used. However that function
makes assumptions that are not true with entry trampoline symbols. For now,
remove the entry trampoline symbols at that point, as they are no longer
needed at that point.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 tools/perf/util/map.h    |  8 ++++++++
 tools/perf/util/symbol.c | 13 +++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
index f1afe1ab6ff7..fafcc375ed37 100644
--- a/tools/perf/util/map.h
+++ b/tools/perf/util/map.h
@@ -8,6 +8,7 @@
 #include <linux/rbtree.h>
 #include <pthread.h>
 #include <stdio.h>
+#include <string.h>
 #include <stdbool.h>
 #include <linux/types.h>
 #include "rwsem.h"
@@ -239,4 +240,11 @@ static inline bool __map__is_kmodule(const struct map *map)
 
 bool map__has_symbols(const struct map *map);
 
+#define ENTRY_TRAMPOLINE_NAME "__entry_SYSCALL_64_trampoline"
+
+static inline bool is_entry_trampoline(const char *name)
+{
+	return !strcmp(name, ENTRY_TRAMPOLINE_NAME);
+}
+
 #endif /* __PERF_MAP_H */
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 701144094183..929058da6727 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -737,12 +737,15 @@ static int map_groups__split_kallsyms(struct map_groups *kmaps, struct dso *dso,
 	struct rb_root *root = &dso->symbols;
 	struct rb_node *next = rb_first(root);
 	int kernel_range = 0;
+	bool x86_64;
 
 	if (!kmaps)
 		return -1;
 
 	machine = kmaps->machine;
 
+	x86_64 = machine__is(machine, "x86_64");
+
 	while (next) {
 		char *module;
 
@@ -790,6 +793,16 @@ static int map_groups__split_kallsyms(struct map_groups *kmaps, struct dso *dso,
 			 */
 			pos->start = curr_map->map_ip(curr_map, pos->start);
 			pos->end   = curr_map->map_ip(curr_map, pos->end);
+		} else if (x86_64 && is_entry_trampoline(pos->name)) {
+			/*
+			 * These symbols are not needed anymore since the
+			 * trampoline maps refer to the text section and it's
+			 * symbols instead. Avoid having to deal with
+			 * relocations, and the assumption that the first symbol
+			 * is the start of kernel text, by simply removing the
+			 * symbols at this point.
+			 */
+			goto discard_symbol;
 		} else if (curr_map != initial_map) {
 			char dso_name[PATH_MAX];
 			struct dso *ndso;
-- 
1.9.1

  parent reply	other threads:[~2018-05-17  9:24 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-17  9:21 [PATCH V2 00/20] perf tools and x86 PTI entry trampolines Adrian Hunter
2018-05-17  9:21 ` [PATCH V2 01/20] kallsyms: Simplify update_iter_mod() Adrian Hunter
2018-05-17  9:21 ` [PATCH V2 02/20] kallsyms, x86: Export addresses of syscall trampolines Adrian Hunter
2018-05-17  9:21 ` [PATCH V2 03/20] x86: Add entry trampolines to kcore Adrian Hunter
2018-05-17 17:52   ` Dave Hansen
2018-05-17 18:09     ` Arnaldo Carvalho de Melo
2018-05-17  9:21 ` [PATCH V2 04/20] x86: kcore: Give entry trampolines all the same offset in kcore Adrian Hunter
2018-05-17 17:54   ` Dave Hansen
2018-05-17  9:21 ` [PATCH V2 05/20] perf tools: Add machine__is() to identify machine arch Adrian Hunter
2018-05-19 11:47   ` [tip:perf/core] perf machine: " tip-bot for Adrian Hunter
2018-05-17  9:21 ` [PATCH V2 06/20] perf tools: Fix kernel_start for PTI on x86 Adrian Hunter
2018-05-19 11:48   ` [tip:perf/core] " tip-bot for Adrian Hunter
2018-05-17  9:21 ` [PATCH V2 07/20] perf tools: Add machine__nr_cpus_avail() Adrian Hunter
2018-05-17  9:21 ` [PATCH V2 08/20] perf tools: Workaround missing maps for x86 PTI entry trampolines Adrian Hunter
2018-05-17  9:21 ` Adrian Hunter [this message]
2018-05-17  9:21 ` [PATCH V2 10/20] perf tools: Allow for extra kernel maps Adrian Hunter
2018-05-17  9:21 ` [PATCH V2 11/20] perf tools: Create maps for x86 PTI entry trampolines Adrian Hunter
2018-05-17  9:22 ` [PATCH V2 12/20] perf tools: Synthesize and process mmap events " Adrian Hunter
2018-05-17  9:22 ` [PATCH V2 13/20] perf buildid-cache: kcore_copy: Keep phdr data in a list Adrian Hunter
2018-05-17  9:22 ` [PATCH V2 14/20] perf buildid-cache: kcore_copy: Keep a count of phdrs Adrian Hunter
2018-05-17  9:22 ` [PATCH V2 15/20] perf buildid-cache: kcore_copy: Calculate offset from phnum Adrian Hunter
2018-05-17  9:22 ` [PATCH V2 16/20] perf buildid-cache: kcore_copy: Layout sections Adrian Hunter
2018-05-17  9:22 ` [PATCH V2 17/20] perf buildid-cache: kcore_copy: Iterate phdrs Adrian Hunter
2018-05-17  9:22 ` [PATCH V2 18/20] perf buildid-cache: kcore_copy: Get rid of kernel_map Adrian Hunter
2018-05-17  9:22 ` [PATCH V2 19/20] perf buildid-cache: kcore_copy: Copy x86 PTI entry trampoline sections Adrian Hunter
2018-05-17  9:22 ` [PATCH V2 20/20] perf buildid-cache: kcore_copy: Amend the offset of sections that remap kernel text Adrian Hunter

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