[PATCH v2 23/23] microblaze: Add support for run time relocation
Michal Simek
monstr at monstr.eu
Tue Jun 7 10:10:40 CEST 2022
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 at amd.com>
---
(no changes since v1)
arch/Kconfig | 1 -
arch/microblaze/Kconfig | 14 +++++
arch/microblaze/config.mk | 5 ++
arch/microblaze/cpu/Makefile | 1 +
arch/microblaze/cpu/relocate.c | 111 +++++++++++++++++++++++++++++++++
arch/microblaze/cpu/start.S | 66 ++++++++++++++++++++
arch/microblaze/cpu/u-boot.lds | 14 +++++
common/board_f.c | 2 +
8 files changed, 213 insertions(+), 1 deletion(-)
create mode 100644 arch/microblaze/cpu/relocate.c
diff --git a/arch/Kconfig b/arch/Kconfig
index 02de32f9c77f..6c8d295d66b2 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -76,7 +76,6 @@ config M68K
config MICROBLAZE
bool "MicroBlaze architecture"
- select NEEDS_MANUAL_RELOC
select SUPPORT_OF_CONTROL
imply CMD_IRQ
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index d7d1b219704e..6f45d19330a1 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -4,6 +4,20 @@ menu "MicroBlaze architecture"
config SYS_ARCH
default "microblaze"
+config NEEDS_MANUAL_RELOC
+ bool "Disable position-independent pre-relocation code"
+ default y
+ help
+ U-Boot expects to be linked to a specific hard-coded address, and to
+ be loaded to and run from that address. This option lifts that
+ restriction, thus allowing the code to be loaded to and executed from
+ almost any 4K aligned address. This logic relies on the relocation
+ information that is embedded in the binary to support U-Boot
+ relocating itself to the top-of-RAM later during execution.
+
+config STATIC_RELA
+ def_bool y if !NEEDS_MANUAL_RELOC
+
choice
prompt "Target select"
optional
diff --git a/arch/microblaze/config.mk b/arch/microblaze/config.mk
index 3e84a832fc12..d35b4f6db7a1 100644
--- a/arch/microblaze/config.mk
+++ b/arch/microblaze/config.mk
@@ -17,6 +17,11 @@ ifeq ($(CONFIG_SPL_BUILD),)
PLATFORM_CPPFLAGS += -fPIC
endif
+ifeq ($(CONFIG_STATIC_RELA),y)
+PLATFORM_CPPFLAGS += -fPIC
+LDFLAGS_u-boot += -pic
+endif
+
ifeq ($(CONFIG_SYS_LITTLE_ENDIAN),y)
PLATFORM_ELFFLAGS += -B microblaze $(OBJCOPYFLAGS) -O elf32-microblazeel
else
diff --git a/arch/microblaze/cpu/Makefile b/arch/microblaze/cpu/Makefile
index f7a83d07b6f6..1feffc6a97c0 100644
--- a/arch/microblaze/cpu/Makefile
+++ b/arch/microblaze/cpu/Makefile
@@ -6,4 +6,5 @@
extra-y = start.o
obj-y = irq.o
obj-y += interrupts.o cache.o exception.o timer.o
+obj-$(CONFIG_STATIC_RELA) += relocate.o
obj-$(CONFIG_SPL_BUILD) += spl.o
diff --git a/arch/microblaze/cpu/relocate.c b/arch/microblaze/cpu/relocate.c
new file mode 100644
index 000000000000..b00d02b1dfcc
--- /dev/null
+++ b/arch/microblaze/cpu/relocate.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * (C) Copyright 2022 Advanced Micro Devices, Inc
+ * Michal Simek <michal.simek at amd.com>
+ */
+
+#include <common.h>
+#include <elf.h>
+
+#define R_MICROBLAZE_NONE 0
+#define R_MICROBLAZE_32 1
+#define R_MICROBLAZE_REL 16
+#define R_MICROBLAZE_GLOB_DAT 18
+
+/**
+ * mb_fix_rela - update relocation to new address
+ * @reloc_addr: new relocation address
+ * @verbose: enable version messages
+ * @rela_start: rela section start
+ * @rela_end: rela section end
+ * @dyn_start: dynamic section start
+ * @origin_addr: address where u-boot starts(doesn't need to be CONFIG_SYS_TEXT_BASE)
+ */
+void mb_fix_rela(u32 reloc_addr, u32 verbose, u32 rela_start,
+ u32 rela_end, u32 dyn_start, u32 origin_addr)
+{
+ u32 num, type, mask, i, reloc_off;
+
+ /*
+ * Return in case u-boot.elf is used directly.
+ * Skip it when u-boot.bin is loaded to different address than
+ * CONFIG_SYS_TEXT_BASE. In this case relocation is necessary to run.
+ */
+ if (reloc_addr == CONFIG_SYS_TEXT_BASE) {
+ debug_cond(verbose,
+ "Relocation address is the same - skip relocation\n");
+ return;
+ }
+
+ reloc_off = reloc_addr - origin_addr;
+
+ debug_cond(verbose, "Relocation address:\t0x%08x\n", reloc_addr);
+ debug_cond(verbose, "Relocation offset:\t0x%08x\n", reloc_off);
+ debug_cond(verbose, "Origin address:\t0x%08x\n", origin_addr);
+ debug_cond(verbose, "Rela start:\t0x%08x\n", rela_start);
+ debug_cond(verbose, "Rela end:\t0x%08x\n", rela_end);
+ debug_cond(verbose, "Dynsym start:\t0x%08x\n", dyn_start);
+
+ num = (rela_end - rela_start) / sizeof(Elf32_Rela);
+
+ debug_cond(verbose, "Number of entries:\t%u\n", num);
+
+ for (i = 0; i < num; i++) {
+ Elf32_Rela *rela;
+ u32 temp;
+
+ rela = (Elf32_Rela *)(rela_start + sizeof(Elf32_Rela) * i);
+
+ mask = 0xffULL; /* would be different on 32-bit */
+ type = rela->r_info & mask;
+
+ debug_cond(verbose, "\nRela possition:\t%d/0x%x\n",
+ i, (u32)rela);
+
+ switch (type) {
+ case R_MICROBLAZE_REL:
+ temp = *(u32 *)rela->r_offset;
+
+ debug_cond(verbose, "Type:\tREL\n");
+ debug_cond(verbose, "Rela r_offset:\t\t0x%x\n", rela->r_offset);
+ debug_cond(verbose, "Rela r_info:\t\t0x%x\n", rela->r_info);
+ debug_cond(verbose, "Rela r_addend:\t\t0x%x\n", rela->r_addend);
+ debug_cond(verbose, "Value at r_offset:\t0x%x\n", temp);
+
+ rela->r_offset += reloc_off;
+ rela->r_addend += reloc_off;
+
+ temp = *(u32 *)rela->r_offset;
+ temp += reloc_off;
+ *(u32 *)rela->r_offset = temp;
+
+ debug_cond(verbose, "New:Rela r_offset:\t0x%x\n", rela->r_offset);
+ debug_cond(verbose, "New:Rela r_addend:\t0x%x\n", rela->r_addend);
+ debug_cond(verbose, "New:Value at r_offset:\t0x%x\n", temp);
+ break;
+ case R_MICROBLAZE_32:
+ case R_MICROBLAZE_GLOB_DAT:
+ debug_cond(verbose, "Type:\t(32/GLOB) %u\n", type);
+ debug_cond(verbose, "Rela r_offset:\t\t0x%x\n", rela->r_offset);
+ debug_cond(verbose, "Rela r_info:\t\t0x%x\n", rela->r_info);
+ debug_cond(verbose, "Rela r_addend:\t\t0x%x\n", rela->r_addend);
+ debug_cond(verbose, "Value at r_offset:\t0x%x\n", temp);
+
+ rela->r_offset += reloc_off;
+
+ temp = *(u32 *)rela->r_offset;
+ temp += reloc_off;
+ *(u32 *)rela->r_offset = temp;
+
+ debug_cond(verbose, "New:Rela r_offset:\t0x%x\n", rela->r_offset);
+ debug_cond(verbose, "New:Value at r_offset:\t0x%x\n", temp);
+ break;
+ case R_MICROBLAZE_NONE:
+ debug_cond(verbose, "R_MICROBLAZE_NONE - skip\n");
+ break;
+ default:
+ debug_cond(verbose, "warning: unsupported relocation type %d at %x\n",
+ type, rela->r_offset);
+ }
+ }
+}
diff --git a/arch/microblaze/cpu/start.S b/arch/microblaze/cpu/start.S
index 72b0f3354731..9a661e785f6d 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 at 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
diff --git a/arch/microblaze/cpu/u-boot.lds b/arch/microblaze/cpu/u-boot.lds
index 2b316cc7f5a5..821cc55d7b30 100644
--- a/arch/microblaze/cpu/u-boot.lds
+++ b/arch/microblaze/cpu/u-boot.lds
@@ -46,6 +46,20 @@ SECTIONS
}
__init_end = . ;
+ . = ALIGN(4);
+ __rel_dyn_start = .;
+ .rela.dyn : {
+ *(.rela.dyn)
+ }
+ __rel_dyn_end = .;
+
+ . = ALIGN(4);
+ __dyn_sym_start = .;
+ .dynsym : {
+ *(.dynsym)
+ }
+ __dyn_sym_end = .;
+
.bss ALIGN(0x4):
{
__bss_start = .;
diff --git a/common/board_f.c b/common/board_f.c
index 51d2f3c365e9..a5666ca77c24 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -684,6 +684,8 @@ static int setup_reloc(void)
#ifdef CONFIG_SYS_TEXT_BASE
#ifdef ARM
gd->reloc_off = gd->relocaddr - (unsigned long)__image_copy_start;
+#elif defined(CONFIG_MICROBLAZE)
+ gd->reloc_off = gd->relocaddr - (u32)_start;
#elif defined(CONFIG_M68K)
/*
* On all ColdFire arch cpu, monitor code starts always
--
2.36.0
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