Not all toolchains use pc relative addresses for global variables.
Apparently the gcc 8.3.0 YOCTO toolchain uses absolute addresses.
This means can't simply return 0 for global_variable_offset() but
instead have to calculate the offset between the compile addresses
for global variables and their runtime address.
We do this by getting the address of a global variable pc relative
explicitely in assembly and substracting that address from the
location the C compiler thinks they are.
Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
---
arch/arm/include/asm/barebox-arm.h | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
diff --git a/arch/arm/include/asm/barebox-arm.h b/arch/arm/include/asm/barebox-arm.h
index 9840482b23..8b2ecd9ab2 100644
--- a/arch/arm/include/asm/barebox-arm.h
+++ b/arch/arm/include/asm/barebox-arm.h
@@ -31,6 +31,7 @@
#include <linux/types.h>
#include <linux/compiler.h>
#include <asm/barebox-arm-head.h>
+#include <asm/sections.h>
/*
* We have a 4GiB address space split into 1MiB sections, with each
@@ -43,15 +44,22 @@ unsigned long get_runtime_offset(void);
/* global_variable_offset() - Access global variables when not running at link address
*
* Get the offset of global variables when not running at the address we are
- * linked at. ARM uses absolute addresses, so we must add the runtime offset
- * whereas aarch64 uses PC relative addresses, so nothing must be done here.
+ * linked at.
*/
static inline unsigned long global_variable_offset(void)
{
- if (IS_ENABLED(CONFIG_CPU_32))
- return get_runtime_offset();
- else
- return 0;
+#ifdef CONFIG_CPU_V8
+ unsigned long text;
+
+ __asm__ __volatile__(
+ "adr %0, _text\n"
+ : "=r" (text)
+ :
+ : "memory");
+ return text - (unsigned long)_text;
+#else
+ return get_runtime_offset();
+#endif
}
void setup_c(void);
--
2.20.1
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