As of gcc 5.2.1 for Thumb-1, it is not possible any more to assign gd from C code, as gd is mapped to r9, and r9 may now be saved in the prolog sequence, and restored in the epilog sequence, of any C functions.
Therefore arch_setup_gd(), which is supposed to set r9, may actually have no effect, causing U-Boot to use a bad address to access GD.
Fix this by never calling arch_setup_gd() for ARM, and instead setting r9 in arch/arm/lib/crt0.S, to the value returned by board_init_f_alloc_reserve().
Signed-off-by: Albert ARIBAUD albert.u.boot@aribaud.net ---
Changes in v6: - moved ARM r9 fix into its own patch
Changes in v5: None Changes in v4: None Changes in v3: None Changes in v2: None
arch/arm/lib/crt0.S | 2 ++ common/init/board_init.c | 8 ++++---- 2 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S index 4f2a712..9c34f2c 100644 --- a/arch/arm/lib/crt0.S +++ b/arch/arm/lib/crt0.S @@ -85,6 +85,8 @@ ENTRY(_main) mov r0, sp bl board_init_f_alloc_reserve mov sp, r0 + /* set up gd here, outside any C code */ + mov r9, r0 bl board_init_f_init_reserve
mov r0, #0 diff --git a/common/init/board_init.c b/common/init/board_init.c index e649e07..d98648e 100644 --- a/common/init/board_init.c +++ b/common/init/board_init.c @@ -21,13 +21,13 @@ DECLARE_GLOBAL_DATA_PTR; #define _USE_MEMCPY #endif
-/* Unfortunately x86 can't compile this code as gd cannot be assigned */ -#ifndef CONFIG_X86 +/* Unfortunately x86 or ARM can't compile this code as gd cannot be assigned */ +#if !defined(CONFIG_X86) && !defined(CONFIG_ARM) __weak void arch_setup_gd(struct global_data *gd_ptr) { gd = gd_ptr; } -#endif /* !CONFIG_X86 */ +#endif /* !CONFIG_X86 && !CONFIG_ARM */
/* * Allocate reserved space for use as 'globals' from 'top' address and @@ -128,7 +128,7 @@ void board_init_f_init_reserve(ulong base) *ptr++ = 0; #endif /* set GD unless architecture did it already */ -#ifndef CONFIG_X86 +#if !defined(CONFIG_X86) && !defined(CONFIG_ARM) arch_setup_gd(gd_ptr); #endif /* next alloc will be higher by one GD plus 16-byte alignment */