microblaze: Add support for run time relocation

Microblaze is using NEEDS_MANUAL_RELOC from the beginnging. This is causing
issues with function pointer arrays which need to be updated manually after
relocation. Building code with -fPIC and linking with -pic will remove this
limitation and there is no longer need to run manual update.

By default still old option is enabled but by disabling NEEDS_MANUAL_RELOC
code will be compiled for full relocation.

The patch does couple of things which are connected to each other.
- Define STATIC_RELA dependency to call relocate-rela to fill sections.
- REMAKE_ELF was already enabled but u-boot file can't be used because
  sections are empty. relocate-rela will fill them and output file is
  u-boot.elf which should be used.
- Add support for full relocation (u-boot.elf)
- Add support for early relocation when u-boot.bin is loaded to different
  address then CONFIG_SYS_TEXT_BASE
- Add rela.dyn and dynsym sections

Disabling NEEDS_MANUAL_RELOC U-Boot size increased by 10% of it's original
size (550kB to 608kB).

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/a845670b34925859b2e321875f7588a29f6655f9.1655299267.git.michal.simek@amd.com

1 files changed, 66 insertions, 0 deletions

diff --git a/arch/microblaze/cpu/start.S b/arch/microblaze/cpu/start.S
index 72b0f335473..9a661e785f6 100644
--- a/arch/microblaze/cpu/start.S
+++ b/arch/microblaze/cpu/start.S
@@ -10,8 +10,16 @@
 #include <asm-offsets.h>
 #include <config.h>
 
+#if defined(CONFIG_STATIC_RELA)
+#define SYM_ADDR(reg, reg_add, symbol)	\
+	mfs	r20, rpc; \
+	addik	r20, r20, _GLOBAL_OFFSET_TABLE_ + 8; \
+	lwi	reg, r20, symbol@GOT; \
+	addk	reg, reg reg_add;
+#else
 #define SYM_ADDR(reg, reg_add, symbol)	\
 	addi	reg, reg_add, symbol
+#endif
 
 	.text
 	.global _start
@@ -27,6 +35,39 @@ _start:
 	addi	r1, r0, CONFIG_SPL_STACK_ADDR
 #else
 	add	r1, r0, r20
+#if defined(CONFIG_STATIC_RELA)
+	bri	1f
+
+	/* Force alignment for easier ASM code below */
+#define ALIGNMENT_ADDR	0x20
+	.align	4
+uboot_dyn_start:
+	.word	__rel_dyn_start
+
+uboot_dyn_end:
+	.word	__rel_dyn_end
+
+uboot_sym_start:
+	.word	__dyn_sym_start
+1:
+
+	addi	r5, r20, 0
+	add	r6, r0, r0
+
+	lwi	r7, r20, ALIGNMENT_ADDR
+	addi	r7, r7, -CONFIG_SYS_TEXT_BASE
+	add	r7, r7, r5
+	lwi	r8, r20, ALIGNMENT_ADDR + 0x4
+	addi	r8, r8, -CONFIG_SYS_TEXT_BASE
+	add	r8, r8, r5
+	lwi	r9, r20, ALIGNMENT_ADDR + 0x8
+	addi	r9, r9, -CONFIG_SYS_TEXT_BASE
+	add	r9, r9, r5
+	addi	r10, r0, CONFIG_SYS_TEXT_BASE
+
+	brlid	r15, mb_fix_rela
+	nop
+#endif
 #endif
 
 	addi	r1, r1, -4	/* Decrement SP to top of memory */
@@ -297,6 +338,30 @@ relocate_code:
 	brlid	r15, __setup_exceptions
 	nop
 
+#if defined(CONFIG_STATIC_RELA)
+	/* reloc_offset is current location */
+	SYM_ADDR(r10, r0, _start)
+
+	/* r5 new address where I should copy code */
+	add	r5, r0, r7 /* Move reloc addr to r5 */
+
+	/* Verbose message */
+	addi	r6, r0, 0
+
+	SYM_ADDR(r7, r0, __rel_dyn_start)
+	rsub	r7, r10, r7
+	add	r7, r7, r5
+	SYM_ADDR(r8, r0, __rel_dyn_end)
+	rsub	r8, r10, r8
+	add	r8, r8, r5
+	SYM_ADDR(r9, r0, __dyn_sym_start)
+	rsub	r9, r10, r9
+	add	r9, r9, r5
+	brlid	r15, mb_fix_rela
+	nop
+
+	/* end of code which does relocation */
+#else
 	/* Check if GOT exist */
 	addik	r21, r23, _got_start
 	addik	r22, r23, _got_end
@@ -314,6 +379,7 @@ relocate_code:
 	cmpu	r12, r21, r22 /* Check if this cross boundary */
 	bneid	r12, 3b
 	addik	r21. r21, 4
+#endif
 
 	/* Flush caches to ensure consistency */
 	addik	r5, r0, 0