[kvm-unit-tests PATCH v2 8/8] arm: stack: add dump_stack support

Andrew Jones
2016-04-19T16:19:49Z

This actually fixes the arm build too, as arm's __builtin_return_address
doesn't allow any input other than zero, and thus the common backtrace()
wasn't compiling.

Signed-off-by: Andrew Jones <drjones@redhat.com>
---
arm/Makefile.arm | 4 ++++
lib/arm/asm/stack.h | 3 +++
lib/arm/processor.c | 1 +
lib/arm/stack.c | 41 +++++++++++++++++++++++++++++++++++++++++
4 files changed, 49 insertions(+)
create mode 100644 lib/arm/stack.c

diff --git a/arm/Makefile.arm b/arm/Makefile.arm
index 946422872532d..92f375700c45e 100644
--- a/arm/Makefile.arm
+++ b/arm/Makefile.arm
@@ -8,12 +8,16 @@ ldarch = elf32-littlearm
kernel_offset = 0x10000
machine = -marm

+# stack.o relies on frame pointers.
+KEEP_FRAME_POINTER := y
+
CFLAGS += $(machine)
CFLAGS += -mcpu=$(PROCESSOR)

cstart.o = $(TEST_DIR)/cstart.o
cflatobjs += lib/arm/spinlock.o
cflatobjs += lib/arm/processor.o
+cflatobjs += lib/arm/stack.o

# arm specific tests
tests =
diff --git a/lib/arm/asm/stack.h b/lib/arm/asm/stack.h
index fe97ac5d4b7d9..ebcedc2ef938c 100644
--- a/lib/arm/asm/stack.h
+++ b/lib/arm/asm/stack.h
@@ -5,4 +5,7 @@
#error Do not directly include <asm/stack.h>. Just use <stack.h>.
#endif

+#define HAVE_ARCH_BACKTRACE_FRAME
+#define HAVE_ARCH_BACKTRACE
+
#endif
diff --git a/lib/arm/processor.c b/lib/arm/processor.c
index 1cef46ab28647..54fdb87ef0196 100644
--- a/lib/arm/processor.c
+++ b/lib/arm/processor.c
@@ -108,6 +108,7 @@ void do_handle_exception(enum vector v, struct pt_regs *regs)
asm volatile("mrc p15, 0, %0, c5, c0, 1": "=r" (fsr));
printf("IFAR: %08lx IFSR: %08lx\n", far, fsr);
}
+ dump_frame_stack((void *)regs->ARM_pc, (void *)regs->ARM_fp);
abort();
}

diff --git a/lib/arm/stack.c b/lib/arm/stack.c
new file mode 100644
index 0000000000000..7d081be7c6d0e
--- /dev/null
+++ b/lib/arm/stack.c
@@ -0,0 +1,41 @@
+/*
+ * backtrace support (this is a modified lib/x86/stack.c)
+ *
+ * Copyright (C) 2016, Red Hat Inc, Andrew Jones <drjones@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.
+ */
+#include <libcflat.h>
+#include <stack.h>
+
+int backtrace_frame(const void *frame, const void **return_addrs,
+ int max_depth)
+{
+ static int walking;
+ int depth;
+ const unsigned long *fp = (unsigned long *)frame;
+
+ if (walking) {
+ printf("RECURSIVE STACK WALK!!!\n");
+ return 0;
+ }
+ walking = 1;
+
+ for (depth = 0; depth < max_depth; depth++) {
+ if (!fp)
+ break;
+ return_addrs[depth] = (void *)fp[0];
+ if (return_addrs[depth] == 0)
+ break;
+ fp = (unsigned long *)fp[-1];
+ }
+
+ walking = 0;
+ return depth;
+}
+
+int backtrace(const void **return_addrs, int max_depth)
+{
+ return backtrace_frame(__builtin_frame_address(0),
+ return_addrs, max_depth);
+}
--
2.4.11