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

[Nadav Amit <nadav.amit@gmail.com>]

From: Nadav Amit <namit@vmware.com>

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