rte_dump_stack needs to be usable in situations when a bug is
encountered and from signal handlers (such as SEGV).
Glibc backtrace_symbols() calls malloc which makes it
dangerous in a signal handler that is handling errors that maybe
due to memory corruption. Additionally, rte_log() is unsafe because
syslog() is not signal safe; printf() is also documented as
not being safe.
This version formats message and uses writev for each line in a manner
similar to what glibc version of backtrace_symbols_fd() does. The
FreeBSD version of backtrace_symbols_fd() is not signal safe.
Sample output:
0: ./build/app/dpdk-testpmd (rte_dump_stack+0x2b) [560a6e9c002b]
1: ./build/app/dpdk-testpmd (main+0xad) [560a6decd5ad]
2: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xcd) [7fd43d3e27fd]
3: ./build/app/dpdk-testpmd (_start+0x2a) [560a6e83628a]
Bugzilla ID: 929
Acked-by: Morten Brørup <m...@smartsharesystems.com>
Signed-off-by: Stephen Hemminger <step...@networkplumber.org>
---
v3
- merge previous two patches into one
common Linux/FreeBSD code.
- rewrite the code to not use functions which are not
documented to be signal safe.
lib/eal/freebsd/eal_debug.c | 43 -------------
lib/eal/freebsd/meson.build | 1 -
lib/eal/include/rte_debug.h | 2 +-
lib/eal/linux/eal_debug.c | 38 -----------
lib/eal/linux/meson.build | 1 -
lib/eal/unix/eal_debug.c | 123 ++++++++++++++++++++++++++++++++++++
lib/eal/unix/meson.build | 1 +
7 files changed, 125 insertions(+), 84 deletions(-)
delete mode 100644 lib/eal/freebsd/eal_debug.c
delete mode 100644 lib/eal/linux/eal_debug.c
create mode 100644 lib/eal/unix/eal_debug.c
diff --git a/lib/eal/freebsd/eal_debug.c b/lib/eal/freebsd/eal_debug.c
deleted file mode 100644
index 64dab4e0da24..000000000000
--- a/lib/eal/freebsd/eal_debug.c
+++ /dev/null
@@ -1,43 +0,0 @@
-/* SPDX-License-Identifier: BSD-3-Clause
- * Copyright(c) 2010-2014 Intel Corporation
- */
-
-#ifdef RTE_BACKTRACE
-#include <execinfo.h>
-#endif
-#include <stdarg.h>
-#include <signal.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <stdint.h>
-
-#include <rte_log.h>
-#include <rte_debug.h>
-#include <rte_common.h>
-#include <rte_eal.h>
-
-#define BACKTRACE_SIZE 256
-
-/* dump the stack of the calling core */
-void rte_dump_stack(void)
-{
-#ifdef RTE_BACKTRACE
- void *func[BACKTRACE_SIZE];
- char **symb = NULL;
- int size;
-
- size = backtrace(func, BACKTRACE_SIZE);
- symb = backtrace_symbols(func, size);
-
- if (symb == NULL)
- return;
-
- while (size > 0) {
- rte_log(RTE_LOG_ERR, RTE_LOGTYPE_EAL,
- "%d: [%s]\n", size, symb[size - 1]);
- size --;
- }
-
- free(symb);
-#endif /* RTE_BACKTRACE */
-}
diff --git a/lib/eal/freebsd/meson.build b/lib/eal/freebsd/meson.build
index 398ceab71d03..85cca5a096ca 100644
--- a/lib/eal/freebsd/meson.build
+++ b/lib/eal/freebsd/meson.build
@@ -7,7 +7,6 @@ sources += files(
'eal.c',
'eal_alarm.c',
'eal_cpuflags.c',
- 'eal_debug.c',
'eal_dev.c',
'eal_hugepage_info.c',
'eal_interrupts.c',
diff --git a/lib/eal/include/rte_debug.h b/lib/eal/include/rte_debug.h
index c4bc71ce28f5..2c4b94a7c9bf 100644
--- a/lib/eal/include/rte_debug.h
+++ b/lib/eal/include/rte_debug.h
@@ -22,7 +22,7 @@ extern "C" {
#endif
/**
- * Dump the stack of the calling core to the console.
+ * Dump the stack of the calling core to the standard error.
*/
void rte_dump_stack(void);
diff --git a/lib/eal/linux/eal_debug.c b/lib/eal/linux/eal_debug.c
deleted file mode 100644
index b0ecf5a9dcde..000000000000
--- a/lib/eal/linux/eal_debug.c
+++ /dev/null
@@ -1,38 +0,0 @@
-/* SPDX-License-Identifier: BSD-3-Clause
- * Copyright(c) 2010-2014 Intel Corporation
- */
-
-#ifdef RTE_BACKTRACE
-#include <execinfo.h>
-#endif
-#include <stdlib.h>
-#include <stdio.h>
-
-#include <rte_log.h>
-#include <rte_debug.h>
-
-#define BACKTRACE_SIZE 256
-
-/* dump the stack of the calling core */
-void rte_dump_stack(void)
-{
-#ifdef RTE_BACKTRACE
- void *func[BACKTRACE_SIZE];
- char **symb = NULL;
- int size;
-
- size = backtrace(func, BACKTRACE_SIZE);
- symb = backtrace_symbols(func, size);
-
- if (symb == NULL)
- return;
-
- while (size > 0) {
- rte_log(RTE_LOG_ERR, RTE_LOGTYPE_EAL,
- "%d: [%s]\n", size, symb[size - 1]);
- size --;
- }
-
- free(symb);
-#endif /* RTE_BACKTRACE */
-}
diff --git a/lib/eal/linux/meson.build b/lib/eal/linux/meson.build
index 65f2ac6b4798..3cccfa36c0a4 100644
--- a/lib/eal/linux/meson.build
+++ b/lib/eal/linux/meson.build
@@ -7,7 +7,6 @@ sources += files(
'eal.c',
'eal_alarm.c',
'eal_cpuflags.c',
- 'eal_debug.c',
'eal_dev.c',
'eal_hugepage_info.c',
'eal_interrupts.c',
diff --git a/lib/eal/unix/eal_debug.c b/lib/eal/unix/eal_debug.c
new file mode 100644
index 000000000000..79b6f2fea2b9
--- /dev/null
+++ b/lib/eal/unix/eal_debug.c
@@ -0,0 +1,123 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2010-2014 Intel Corporation
+ */
+
+#include <rte_debug.h>
+
+
+#ifdef RTE_BACKTRACE
+
+#include <dlfcn.h>
+#include <execinfo.h>
+#include <string.h>
+#include <sys/uio.h>
+#include <unistd.h>
+
+#define BACKTRACE_SIZE 256
+
+/*
+ * Convert number to string and return start of string.
+ * Note: string does not start at beginning of buffer.
+ */
+static char *safe_itoa(long val, char *buf, size_t len, unsigned int radix)
+{
+ char *bp = buf + len;
+ static const char hexdigit[] = "0123456789abcdef";
+
+ *--bp = '\0'; /* Null terminate the string */
+ do {
+ /* if buffer is not big enough, then truncate */
+ if (bp == buf)
+ return bp;
+
+ *--bp = hexdigit[val % radix];
+ val /= radix;
+ } while (val != 0);
+
+ return bp;
+}
+
+
+/* Dump the stack of the calling core
+ *
+ * To be safe in signal handler requires limiting what functions are
+ * used in this code since may be called from inside libc or
+ * when malloc poll is corrupt.
+ *
+ * Most of libc is therefore not safe, include RTE_LOG (calls syslog);
+ * backtrace_symbols (calls malloc), etc.
+ */
+void rte_dump_stack(void)
+{
+ void *func[BACKTRACE_SIZE];
+ Dl_info info;
+ char buf1[8], buf2[32], buf3[32], buf4[32];
+ struct iovec iov[10];
+ int i, size;
+
+ size = backtrace(func, BACKTRACE_SIZE);
+
+ for (i = 0; i < size; i++) {
+ struct iovec *io = iov;
+ char *str;
+ uintptr_t base;
+ long offset;
+ void *pc = func[i];
+
+/* Macro to put string onto set of iovecs
+ * cast is to suppress warnings about lose of const qualifier
+ */
+#define PUSH_IOV(io, str) { \
+ (io)->iov_base = (char *)(uintptr_t)str; \
+ (io)->iov_len = strlen(str); \
+ ++io; }
+
+ /* output stack frame number */
+ str = safe_itoa(i, buf1, sizeof(buf1), 10);
+ PUSH_IOV(io, str); /* iov[0] */
+ PUSH_IOV(io, ": "); /* iov[1] */
+
+ /* Lookup the symbol information */
+ if (dladdr (pc, &info) == 0) {
+ PUSH_IOV(io, "?? [");
+ } else {
+ const char *fname;
+
+ if (info.dli_fname && *info.dli_fname)
+ fname = info.dli_fname;
+ else
+ fname = "(vdso)";
+ PUSH_IOV(io, fname); /* iov[2] */
+ PUSH_IOV(io, " ("); /* iov[3] */
+
+ if (info.dli_saddr != NULL) {
+ PUSH_IOV(io, info.dli_sname); /* iov[4] */
+ base = (uintptr_t)info.dli_saddr;
+ } else {
+ str = safe_itoa((unsigned long)info.dli_fbase,
+ buf3, sizeof(buf3), 16);
+ PUSH_IOV(io, str);
+ base = (uintptr_t)info.dli_fbase;
+ }
+
+ PUSH_IOV(io, "+0x"); /* iov[5] */
+
+ offset = (uintptr_t)pc - base;
+ str = safe_itoa(offset, buf4, sizeof(buf4), 16);
+ PUSH_IOV(io, str); /* iov[6] */
+
+ PUSH_IOV(io, ") ["); /* iov[7] */
+ }
+
+ str = safe_itoa((unsigned long)pc, buf2, sizeof(buf2), 16);
+ PUSH_IOV(io, str); /* iov[8] */
+ PUSH_IOV(io, "]\n"); /* iov[9] */
+
+ if (writev(STDERR_FILENO, iov, io - iov) < 0)
+ break;
+ }
+}
+#else
+/* stub if not enabled */
+void rte_dump_stack(void) { }
+#endif /* RTE_BACKTRACE */
diff --git a/lib/eal/unix/meson.build b/lib/eal/unix/meson.build
index a22ea7cabc46..9c59f3d31693 100644
--- a/lib/eal/unix/meson.build
+++ b/lib/eal/unix/meson.build
@@ -2,6 +2,7 @@
# Copyright(c) 2020 Dmitry Kozlyuk
sources += files(
+ 'eal_debug.c',
'eal_file.c',
'eal_unix_memory.c',
'eal_unix_timer.c',
--
2.35.1
