riscv: Access gd with inline assembly when building with LTO or Clang
Similar to AArch64's case, Clang may wrongly fold accesses to gd pointer
which is defined with register qualifier into constants, breaking
various components.
This patch defines gd as a macro when building with Clang or LTO, which
expands to get_gd() that accesses gp pointer in assembly, making RISC-V
ports function properly and preparing for introduction of LTO in the
future. Board initialization code is also adapted for non-assignable gd.
Reported-by: Nathaniel Hourt <I@nathaniel.land>
Signed-off-by: Yao Zi <ziyao@disroot.org>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
diff --git a/arch/riscv/include/asm/global_data.h b/arch/riscv/include/asm/global_data.h
index d356752..47b5e2c 100644
--- a/arch/riscv/include/asm/global_data.h
+++ b/arch/riscv/include/asm/global_data.h
@@ -14,6 +14,7 @@
#include <asm/smp.h>
#include <asm/u-boot.h>
#include <compiler.h>
+#include <config.h>
/* Architecture-specific global data */
struct arch_global_data {
@@ -47,8 +48,26 @@
#include <asm-generic/global_data.h>
+#if defined(__clang__) || CONFIG_IS_ENABLED(LTO)
+
+#define DECLARE_GLOBAL_DATA_PTR
+#define gd get_gd()
+
+static inline gd_t *get_gd(void)
+{
+ gd_t *gd_ptr;
+
+ __asm__ volatile ("mv %0, gp\n" : "=r" (gd_ptr));
+
+ return gd_ptr;
+}
+
+#else
+
#define DECLARE_GLOBAL_DATA_PTR register gd_t *gd asm ("gp")
+#endif
+
static inline void set_gd(volatile gd_t *gd_ptr)
{
#ifdef CONFIG_64BIT