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
diff --git a/arch/microblaze/cpu/start.S b/arch/microblaze/cpu/start.S
index 72b0f33..9a661e7 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 @@
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 @@
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 @@
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