[PATCH-V2] perf/probe: verify instruction/offset in perf before adding a uprobe

Prashanth Nageshappa
2012-04-24T06:37:18Z

This patch is to augment Srikar's perf support for uprobes patch
(https://lkml.org/lkml/2012/4/11/191) with the following features:

a. Instruction verification for user space tracing
b. Function boundary validation support to uprobes as its kernel
counterpart (Commit-ID: 1c1bc922).

This will help in ensuring uprobe is placed at right location inside
the intended function.

To verify instructions in perf before adding a uprobe, we need to use
arch/x86/lib/insn.c. Since perf Makefile enables -Wswitch-default flag
it causes build warnings/failures. Masami's patch
https://lkml.org/lkml/2012/4/12/598 addresses those warnings and it is
a pre-req for this patch.

v2 addresses Masami's review comments: Rebuild insn.c and inat.c while
building perf and a few other minor ones.

Signed-off-by: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com>
---

tools/perf/Makefile | 1
tools/perf/arch/x86/Makefile | 20 ++++++++
tools/perf/arch/x86/util/probe-event.c | 84 ++++++++++++++++++++++++++++++++
tools/perf/util/include/linux/string.h | 1
tools/perf/util/probe-event.c | 22 ++++++++
tools/perf/util/probe-event.h | 2 +
tools/perf/util/symbol.c | 2 +
tools/perf/util/symbol.h | 1
8 files changed, 132 insertions(+), 1 deletions(-)
create mode 100644 tools/perf/arch/x86/util/probe-event.c

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 820371f..94879b9 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -61,6 +61,7 @@ ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \

CC = $(CROSS_COMPILE)gcc
AR = $(CROSS_COMPILE)ar
+AWK = awk

# Additional ARCH settings for x86
ifeq ($(ARCH),i386)
diff --git a/tools/perf/arch/x86/Makefile b/tools/perf/arch/x86/Makefile
index 744e629..1a7215b 100644
--- a/tools/perf/arch/x86/Makefile
+++ b/tools/perf/arch/x86/Makefile
@@ -1,5 +1,25 @@
+inat_tables_script = ../../arch/$(ARCH)/tools/gen-insn-attr-x86.awk
+inat_tables_maps = ../../arch/$(ARCH)/lib/x86-opcode-map.txt
+cmd_inat_tables = $(AWK) -f $(inat_tables_script) $(inat_tables_maps) > $@ || rm -f $@
+
+BASIC_CFLAGS += -I. -I../../arch/$(ARCH)/include
+
ifndef NO_DWARF
PERF_HAVE_DWARF_REGS := 1
LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/dwarf-regs.o
endif
LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/header.o
+LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/probe-event.o
+LIB_OBJS += $(OUTPUT)arch/$(ARCH)/inat.o
+LIB_OBJS += $(OUTPUT)arch/$(ARCH)/insn.o
+
+$(OUTPUT)arch/$(ARCH)/inat.o:../../arch/$(ARCH)/lib/inat-tables.c
+
+../../arch/$(ARCH)/lib/inat-tables.c: $(inat_tables_script) $(inat_tables_maps)
+ $(cmd_inat_tables)
+
+$(OUTPUT)arch/$(ARCH)/inat.o:../../arch/$(ARCH)/lib/inat.c $(OUTPUT)PERF-CFLAGS
+ $(QUIET_CC)$(CC) -o $@ -c $(ALL_CFLAGS) $<
+
+$(OUTPUT)arch/$(ARCH)/insn.o:../../arch/$(ARCH)/lib/insn.c $(OUTPUT)PERF-CFLAGS
+ $(QUIET_CC)$(CC) -o $@ -c $(ALL_CFLAGS) $<
diff --git a/tools/perf/arch/x86/util/probe-event.c b/tools/perf/arch/x86/util/probe-event.c
new file mode 100644
index 0000000..7df9031
--- /dev/null
+++ b/tools/perf/arch/x86/util/probe-event.c
@@ -0,0 +1,84 @@
+/*
+ * probe-event.c : x86 specific perf-probe definition
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2011-2012
+ * Authors:
+ * Prashanth Nageshappa
+ */
+
+#include <util/types.h>
+#include <util/probe-event.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#include <errno.h>
+#include <asm/insn.h>
+#include <elf.h>
+
+/*
+ * Check if a given offset from start of a function is valid or not
+ */
+bool can_probe(char *name, unsigned long long vaddr, unsigned long offset,
+ u8 class)
+{
+ unsigned long long eaddr, saddr;
+ unsigned long fileoffset, readbytes;
+ int fd = 0;
+ bool ret = false;
+ char *buf = NULL;
+ struct insn insn;
+
+ fd = open(name, O_RDONLY);
+ if (fd == -1) {
+ pr_warning("Failed to open %s: %s\n", name, strerror(errno));
+ return ret;
+ }
+ buf = (char *)malloc(offset + MAX_INSN_SIZE);
+ if (buf == NULL) {
+ pr_warning("Failed to allocate memory");
+ goto out;
+ }
+ fileoffset = lseek(fd, vaddr, SEEK_SET);
+ if (fileoffset != vaddr) {
+ pr_warning("Failed to lseek %s: %s\n", name, strerror(errno));
+ goto out;
+ }
+ saddr = (unsigned long long)buf;
+ eaddr = (unsigned long long)buf + offset;
+ readbytes = read(fd, buf, offset + MAX_INSN_SIZE);
+ if (readbytes != offset + MAX_INSN_SIZE) {
+ pr_warning("Failed to read %s: %s\n", name, strerror(errno));
+ goto out;
+ }
+ while (saddr < eaddr) {
+ insn_init(&insn, (void *)saddr, class == ELFCLASS64);
+ insn_get_length(&insn);
+ saddr += insn.length;
+ }
+ ret = (saddr == eaddr);
+
+out:
+ if (buf)
+ free(buf);
+
+ if (fd)
+ close(fd);
+
+ return ret;
+}
diff --git a/tools/perf/util/include/linux/string.h b/tools/perf/util/include/linux/string.h
index 3b2f590..9d5eb21 100644
--- a/tools/perf/util/include/linux/string.h
+++ b/tools/perf/util/include/linux/string.h
@@ -1 +1,2 @@
#include <string.h>
+#include <perf.h>
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index b7dec82..8f3de61 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -2254,6 +2254,17 @@ int show_available_funcs(const char *target, struct strfilter *_filter,
}

/*
+ * Check if a given offset from start of a function is valid or not
+ */
+bool __attribute__((weak)) can_probe(char *name __used,
+ unsigned long long vaddr __used,
+ unsigned long offset __used,
+ u8 class __used)
+{
+ return true;
+}
+
+/*
* uprobe_events only accepts address:
* Convert function and any offset to address
*/
@@ -2307,7 +2318,16 @@ static int convert_name_to_addr(struct perf_probe_event *pev, const char *exec)

if (map->start > sym->start)
vaddr = map->start;
- vaddr += sym->start + pp->offset + map->pgoff;
+
+ vaddr += sym->start + map->pgoff;
+ if (pp->offset)
+ if ((vaddr + pp->offset > sym->end) ||
+ !can_probe(name, vaddr, pp->offset,
+ map->dso->class)) {
+ pr_err("Failed to insert probe, ensure offset is within function and on insn boundary.\n");
+ return -EINVAL;
+ }
+ vaddr += pp->offset;
pp->offset = 0;

if (!pev->event) {
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index f9f3de8..af96594 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -137,4 +137,6 @@ extern int show_available_funcs(const char *module, struct strfilter *filter,
/* Maximum index number of event-name postfix */
#define MAX_EVENT_INDEX 1024

+extern bool can_probe(char *name, unsigned long long vaddr,
+ unsigned long offset, u8 class);
#endif /*_PROBE_EVENT_H */
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index caaf75a..be58b06 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1184,6 +1184,7 @@ static int dso__load_sym(struct dso *dso, struct map *map, const char *name,
goto out_close;
}

+ dso->class = gelf_getclass(elf);
if (gelf_getehdr(elf, &ehdr) == NULL) {
pr_debug("%s: cannot get elf header.\n", __func__);
goto out_elf_end;
@@ -1326,6 +1327,7 @@ static int dso__load_sym(struct dso *dso, struct map *map, const char *name,
curr_dso->kernel = dso->kernel;
curr_dso->long_name = dso->long_name;
curr_dso->long_name_len = dso->long_name_len;
+ curr_dso->class = dso->class;
curr_map = map__new2(start, curr_dso,
map->type);
if (curr_map == NULL) {
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 9e7742c..1d0cc28 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -174,6 +174,7 @@ struct dso {
char *long_name;
u16 long_name_len;
u16 short_name_len;
+ u8 class;
char name[0];
};