[kvm-unit-tests PATCH v3 2/6] lib/stack: print base addresses on relocation setups

Nadav Amit
2023-06-28T00:14:43Z

Making sense from dumped stacks when running EFI tests is very hard due
to the relocation. Fix it by adjusting the address back to the original
address.

Introduce CONFIG_RELOC, which would be set on arm64 and on EFI configs.

Suggested-by: Andrew Jones <andrew.jones@linux.dev>
Signed-off-by: Nadav Amit <namit@vmware.com>

---
v2->v3:
* Mark PowerPC as relocatable as well [Andrew]
* Fixing incorrect Makefile [Andrew]

v1->v2:
* Introduce CONFIG_RELOC to support ARM64 [Andrew]
---
Makefile | 2 +-
arm/Makefile.arm64 | 1 +
lib/stack.c | 31 +++++++++++++++++++++++++++++--
powerpc/Makefile.common | 1 +
4 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index 307bc29..ae79059 100644
--- a/Makefile
+++ b/Makefile
@@ -40,7 +40,7 @@ OBJDIRS += $(LIBFDT_objdir)

# EFI App
ifeq ($(CONFIG_EFI),y)
-EFI_CFLAGS := -DCONFIG_EFI
+EFI_CFLAGS := -DCONFIG_EFI -DCONFIG_RELOC
# The following CFLAGS and LDFLAGS come from:
# - GNU-EFI/Makefile.defaults
# - GNU-EFI/apps/Makefile
diff --git a/arm/Makefile.arm64 b/arm/Makefile.arm64
index eada7f9..85b3348 100644
--- a/arm/Makefile.arm64
+++ b/arm/Makefile.arm64
@@ -12,6 +12,7 @@ CFLAGS += -mstrict-align

mno_outline_atomics := $(call cc-option, -mno-outline-atomics, "")
CFLAGS += $(mno_outline_atomics)
+CFLAGS += -DCONFIG_RELOC

define arch_elf_check =
$(if $(shell ! $(READELF) -rW $(1) >&/dev/null && echo "nok"),
diff --git a/lib/stack.c b/lib/stack.c
index bdb23fd..dd6bfa8 100644
--- a/lib/stack.c
+++ b/lib/stack.c
@@ -6,13 +6,38 @@
*/

#include <libcflat.h>
+#include <stdbool.h>
#include <stack.h>

#define MAX_DEPTH 20

+#ifdef CONFIG_RELOC
+extern char _text, _etext;
+
+static bool base_address(const void *rebased_addr, unsigned long *addr)
+{
+ unsigned long ra = (unsigned long)rebased_addr;
+ unsigned long start = (unsigned long)&_text;
+ unsigned long end = (unsigned long)&_etext;
+
+ if (ra < start || ra >= end)
+ return false;
+
+ *addr = ra - start;
+ return true;
+}
+#else
+static bool base_address(const void *rebased_addr, unsigned long *addr)
+{
+ *addr = (unsigned long)rebased_addr;
+ return true;
+}
+#endif
+
static void print_stack(const void **return_addrs, int depth,
bool top_is_return_address)
{
+ unsigned long addr;
int i = 0;

printf("\tSTACK:");
@@ -20,12 +45,14 @@ static void print_stack(const void **return_addrs, int depth,
/* @addr indicates a non-return address, as expected by the stack
* pretty printer script. */
if (depth > 0 && !top_is_return_address) {
- printf(" @%lx", (unsigned long) return_addrs[0]);
+ if (base_address(return_addrs[0], &addr))
+ printf(" @%lx", addr);
i++;
}

for (; i < depth; i++) {
- printf(" %lx", (unsigned long) return_addrs[i]);
+ if (base_address(return_addrs[i], &addr))
+ printf(" %lx", addr);
}
printf("\n");
}
diff --git a/powerpc/Makefile.common b/powerpc/Makefile.common
index 8ce0034..c2e976e 100644
--- a/powerpc/Makefile.common
+++ b/powerpc/Makefile.common
@@ -24,6 +24,7 @@ CFLAGS += -ffreestanding
CFLAGS += -O2 -msoft-float -mno-altivec $(mabi_no_altivec)
CFLAGS += -I $(SRCDIR)/lib -I $(SRCDIR)/lib/libfdt -I lib
CFLAGS += -Wa,-mregnames
+CFLAGS += -DCONFIG_RELOC

# We want to keep intermediate files
.PRECIOUS: %.o
--
2.34.1