From: Oleksij Rempel <linux@xxxxxxxxxxxxxxxx>
this patch i a port of following patch from u-boot with some additional
integration changes and fixes of original code:
| Subject: [PATCH] MIPS: Stop building position independent code
|
| U-Boot has up until now built with -fpic for the MIPS architecture,
| producing position independent code which uses indirection through a
| global offset table, making relocation fairly straightforward as it
| simply involves patching up GOT entries.
|
| Using -fpic does however have some downsides. The biggest of these is
| that generated code is bloated in various ways. For example, function
| calls are indirected through the GOT & the t9 register:
|
| 8f998064 lw t9,-32668(gp)
| 0320f809 jalr t9
|
| Without -fpic the call is simply:
|
| 0f803f01 jal be00fc04 <puts>
|
| This is more compact & faster (due to the lack of the load & the
| dependency the jump has on its result). It is also easier to read &
| debug because the disassembly shows what function is being called,
| rather than just an offset from gp which would then have to be looked up
| in the ELF to discover the target function.
|
| Another disadvantage of -fpic is that each function begins with a
| sequence to calculate the value of the gp register, for example:
|
| 3c1c0004 lui gp,0x4
| 279c3384 addiu gp,gp,13188
| 0399e021 addu gp,gp,t9
|
| Without using -fpic this sequence no longer appears at the start of each
| function, reducing code size considerably.
|
| This patch switches U-Boot from building with -fpic to building with
| -fno-pic, in order to gain the benefits described above. The cost of
| this is an extra step during the build process to extract relocation
| data from the ELF & write it into a new .rel section in a compact
| format, plus the added complexity of dealing with multiple types of
| relocation rather than the single type that applied to the GOT. The
| benefit is smaller, cleaner, more debuggable code. The relocate_code()
| function is reimplemented in C to handle the new relocation scheme,
| which also makes it easier to read & debug.
|
| Taking maltael_defconfig as an example the size of u-boot.bin built
| using the Codescape MIPS 2016.05-06 toolchain (gcc 4.9.2, binutils
| 2.24.90) shrinks from 254KiB to 224KiB.
|
| Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
Signed-off-by: Oleksij Rempel <linux@xxxxxxxxxxxxxxxx>
---
Makefile | 2 +-
arch/mips/Kconfig | 18 ++
arch/mips/Makefile | 11 +-
arch/mips/boot/main_entry-pbl.c | 4 +-
arch/mips/boot/start.S | 4 +-
arch/mips/include/asm/relocs.h | 23 ++
arch/mips/include/asm/sections.h | 14 +
arch/mips/lib/Makefile | 2 +
arch/mips/lib/barebox.lds.S | 27 +-
arch/mips/lib/reloc.c | 182 +++++++++++++
arch/mips/lib/sections.c | 9 +
scripts/Makefile | 1 +
scripts/mips-relocs.c | 426 +++++++++++++++++++++++++++++++
13 files changed, 714 insertions(+), 9 deletions(-)
create mode 100644 arch/mips/include/asm/relocs.h
create mode 100644 arch/mips/lib/reloc.c
create mode 100644 arch/mips/lib/sections.c
create mode 100644 scripts/mips-relocs.c
diff --git a/Makefile b/Makefile
index f8c3d75575..ad4d0d319c 100644
--- a/Makefile
+++ b/Makefile
@@ -183,7 +183,7 @@ HOST_LFS_LIBS := $(shell getconf LFS_LIBS)
HOSTCC = gcc
HOSTCXX = g++
-HOSTCFLAGS = -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer $(HOST_LFS_CFLAGS)
+HOSTCFLAGS = -Wall -ggdb -Wstrict-prototypes -O2 -fomit-frame-pointer $(HOST_LFS_CFLAGS)
HOSTCXXFLAGS = -O2 $(HOST_LFS_CFLAGS)
HOSTLDFLAGS = $(HOST_LFS_LDFLAGS)
HOST_LOADLIBES = $(HOST_LFS_LIBS)
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index eab9452de9..49f238df58 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -32,6 +32,24 @@ config PHYS_ADDR_T_64BIT
menu "Machine selection"
+config MIPS_RELOCATION_TABLE_SIZE
+ hex "Relocation table size"
+ range 0x100 0x10000
+ default "0x8000"
+ ---help---
+ A table of relocation data will be appended to the Barebox binary
+ and parsed in relocate_code() to fix up all offsets in the relocated
+ Barebox.
+
+ This option allows the amount of space reserved for the table to be
+ adjusted in a range from 256 up to 64k. The default is 32k and should
+ be ok in most cases. Reduce this value to shrink the size of U-Boot
+ binary.
+
+ The build will fail and a valid size suggested if this is too small.
+
+ If unsure, leave at the default value.
+
config BUILTIN_DTB
bool "link a DTB into the barebox image"
depends on OFTREE
diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index 5fbd51ceee..5eccf18fe4 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -11,7 +11,7 @@ endif
CPPFLAGS += -D__MIPS__ -fno-strict-aliasing -fno-merge-constants
-cflags-y += -G 0 -mno-abicalls -fno-pic -pipe
+cflags-y += -G 0 -mno-abicalls -pipe
cflags-y += -Wall -Wstrict-prototypes \
-Wno-uninitialized -Wno-format -Wno-main
@@ -59,7 +59,7 @@ CPPFLAGS += -DTEXT_BASE=$(CONFIG_TEXT_BASE)
ifndef CONFIG_MODULES
# Add cleanup flags
CPPFLAGS += -fdata-sections -ffunction-sections
-LDFLAGS_barebox += -static --gc-sections
+LDFLAGS_barebox += -static --gc-sections --emit-relocs
endif
ifdef CONFIG_IMAGE_COMPRESSION
@@ -116,6 +116,13 @@ CFLAGS += $(cflags-y)
lds-$(CONFIG_GENERIC_LINKER_SCRIPT) := arch/mips/lib/barebox.lds
+cmd_barebox__ ?= $(LD) $(LDFLAGS) $(LDFLAGS_barebox) -o $@ \
+ -T $(barebox-lds) \
+ --start-group $(barebox-common) --end-group \
+ $(filter-out $(barebox-lds) $(barebox-common) FORCE ,$^); \
+ $(srctree)/scripts/mips-relocs $@
+
+
CLEAN_FILES += arch/mips/lib/barebox.lds barebox.map barebox.S
pbl := arch/mips/pbl
diff --git a/arch/mips/boot/main_entry-pbl.c b/arch/mips/boot/main_entry-pbl.c
index 28eaa8791f..60be645148 100644
--- a/arch/mips/boot/main_entry-pbl.c
+++ b/arch/mips/boot/main_entry-pbl.c
@@ -38,7 +38,7 @@ void __section(.text_entry) pbl_main_entry(void *fdt, void *fdt_end,
{
u32 pg_start, pg_end, pg_len, fdt_len;
void *fdt_new;
- void (*barebox)(void *fdt, u32 fdt_len);
+ void (*barebox)(void *fdt, u32 fdt_len, u32 ram_size);
puts_ll("pbl_main_entry()\n");
@@ -56,5 +56,5 @@ void __section(.text_entry) pbl_main_entry(void *fdt, void *fdt_end,
memcpy(fdt_new, fdt, fdt_len);
barebox = (void *)TEXT_BASE;
- barebox(fdt_new, fdt_len);
+ barebox(fdt_new, fdt_len, ram_size);
}
diff --git a/arch/mips/boot/start.S b/arch/mips/boot/start.S
index 6efe03e98d..c1cd2d9dd5 100644
--- a/arch/mips/boot/start.S
+++ b/arch/mips/boot/start.S
@@ -18,6 +18,7 @@ EXPORT(_start)
/* save dtb pointer */
move s0, a0
move s1, a1
+ move s2, a2
/* disable watchpoints */
mtc0 zero, CP0_WATCHLO
@@ -32,7 +33,8 @@ EXPORT(_start)
/* restore dtb pointer */
move a0, s0
move a1, s1
- la v0, main_entry
+ move a2, s2
+ la v0, relocate_code
jal v0
nop
diff --git a/arch/mips/include/asm/relocs.h b/arch/mips/include/asm/relocs.h
new file mode 100644
index 0000000000..0987c4bb13
--- /dev/null
+++ b/arch/mips/include/asm/relocs.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * MIPS Relocations
+ *
+ * Copyright (c) 2017 Imagination Technologies Ltd.
+ */
+
+#ifndef __ASM_MIPS_RELOCS_H__
+#define __ASM_MIPS_RELOCS_H__
+
+#define R_MIPS_NONE 0
+#define R_MIPS_32 2
+#define R_MIPS_26 4
+#define R_MIPS_HI16 5
+#define R_MIPS_LO16 6
+#define R_MIPS_PC16 10
+#define R_MIPS_64 18
+#define R_MIPS_HIGHER 28
+#define R_MIPS_HIGHEST 29
+#define R_MIPS_PC21_S2 60
+#define R_MIPS_PC26_S2 61
+
+#endif /* __ASM_MIPS_RELOCS_H__ */
diff --git a/arch/mips/include/asm/sections.h b/arch/mips/include/asm/sections.h
index 2b8c516038..8e004eaf34 100644
--- a/arch/mips/include/asm/sections.h
+++ b/arch/mips/include/asm/sections.h
@@ -1 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#ifndef __ASM_MIPS_SECTIONS_H
+#define __ASM_MIPS_SECTIONS_H
+
#include <asm-generic/sections.h>
+
+/**
+ * __rel_start: Relocation data generated by the mips-relocs tool
+ *
+ * See arch/mips/lib/reloc.c for details on the format & use of this data.
+ */
+extern uint8_t __rel_start[];
+
+#endif
diff --git a/arch/mips/lib/Makefile b/arch/mips/lib/Makefile
index 7372e8dc27..4ba42e526e 100644
--- a/arch/mips/lib/Makefile
+++ b/arch/mips/lib/Makefile
@@ -4,6 +4,8 @@ obj-y += cpu-probe.o
lwl-y += end.o
obj-y += traps.o
obj-y += genex.o
+obj-y += reloc.o
+obj-y += sections.o
obj-y += shutdown.o
obj-y += dma-default.o
diff --git a/arch/mips/lib/barebox.lds.S b/arch/mips/lib/barebox.lds.S
index 8ddf954517..58b0c5919d 100644
--- a/arch/mips/lib/barebox.lds.S
+++ b/arch/mips/lib/barebox.lds.S
@@ -13,6 +13,8 @@ SECTIONS
. = TEXT_BASE;
. = ALIGN(4);
+
+ .image_start : { *(.__image_start) }
.text :
{
_stext = .;
@@ -79,9 +81,28 @@ SECTIONS
.dtb : { BAREBOX_DTB() }
_edata = .;
+ .image_end : { *(.__image_end) }
+
. = ALIGN(4);
- __bss_start = .;
- .bss : { *(.bss*) }
- __bss_stop = .;
+ /*
+ * .rel must come last so that the mips-relocs tool can shrink
+ * the section size & the PT_LOAD program header filesz.
+ */
+ .data.reloc : {
+ __rel_start = .;
+ BYTE(0x0)
+ . += (32 * 1024) - 1;
+ }
+
_end = .;
+
+ .bss __rel_start (OVERLAY) : {
+ __bss_start = .;
+ *(.sbss.*)
+ *(.bss.*)
+ *(COMMON)
+ . = ALIGN(4);
+ __bss_stop = .;
+ }
+
}
diff --git a/arch/mips/lib/reloc.c b/arch/mips/lib/reloc.c
new file mode 100644
index 0000000000..9756d61666
--- /dev/null
+++ b/arch/mips/lib/reloc.c
@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * MIPS Relocation
+ *
+ * Copyright (c) 2017 Imagination Technologies Ltd.
+ *
+ * Relocation data, found in the .rel section, is generated by the mips-relocs
+ * tool & contains a record of all locations in the Barebox binary that need to
+ * be fixed up during relocation.
+ *
+ * The data is a sequence of unsigned integers, which are of somewhat arbitrary
+ * size. This is achieved by encoding integers as a sequence of bytes, each of
+ * which contains 7 bits of data with the most significant bit indicating
+ * whether any further bytes need to be read. The least significant bits of the
+ * integer are found in the first byte - ie. it somewhat resembles little
+ * endian.
+ *
+ * Each pair of two integers represents a relocation that must be applied. The
+ * first integer represents the type of relocation as a standard ELF relocation
+ * type (ie. R_MIPS_*). The second integer represents the offset at which to
+ * apply the relocation, relative to the previous relocation or for the first
+ * relocation the start of the relocated .text section.
+ *
+ * The end of the relocation data is indicated when type R_MIPS_NONE (0) is
+ * read, at which point no further integers should be read. That is, the
+ * terminating R_MIPS_NONE reloc includes no offset.
+ */
+
+#include <common.h>
+
+#include <asm/bitops.h>
+#include <asm/cache.h>
+#include <asm/cacheops.h>
+#include <asm/cpu.h>
+#include <asm/cpu-info.h>
+#include <asm/io.h>
+#include <asm/mipsregs.h>
+#include <asm/relocs.h>
+#include <asm/sections.h>
+#include <linux/sizes.h>
+#include <asm-generic/memory_layout.h>
+
+#define MAX_BSS_SIZE SZ_1M
+
+void main_entry(void *fdt, u32 fdt_size);
+void relocate_code(void *fdt, u32 fdt_size, u32 relocaddr);
+
+/**
+ * read_uint() - Read an unsigned integer from the buffer
+ * @buf: pointer to a pointer to the reloc buffer
+ *
+ * Read one whole unsigned integer from the relocation data pointed to by @buf,
+ * advancing @buf past the bytes encoding the integer.
+ *
+ * Returns: the integer read from @buf
+ */
+static unsigned long read_uint(uint8_t **buf)
+{
+ unsigned long val = 0;
+ unsigned int shift = 0;
+ uint8_t new;
+
+ do {
+ new = *(*buf)++;
+ val |= (new & 0x7f) << shift;
+ shift += 7;
+ } while (new & 0x80);
+
+ return val;
+}
+
+/**
+ * apply_reloc() - Apply a single relocation
+ * @type: the type of reloc (R_MIPS_*)
+ * @addr: the address that the reloc should be applied to
+ * @off: the relocation offset, ie. number of bytes we're moving Barebox by
+ *
+ * Apply a single relocation of type @type at @addr. This function is
+ * intentionally simple, and does the bare minimum needed to fixup the
+ * relocated Barebox - in particular, it does not check for overflows.
+ */
+static void apply_reloc(unsigned int type, void *addr, long off)
+{
+ uint32_t u32;
+
+ switch (type) {
+ case R_MIPS_26:
+ u32 = *(uint32_t *)addr;
+ u32 = (u32 & GENMASK(31, 26)) |
+ ((u32 + (off >> 2)) & GENMASK(25, 0));
+ *(uint32_t *)addr = u32;
+ break;
+
+ case R_MIPS_32:
+ *(uint32_t *)addr += off;
+ break;
+
+ case R_MIPS_64:
+ *(uint64_t *)addr += off;
+ break;
+
+ case R_MIPS_HI16:
+ *(uint32_t *)addr += off >> 16;
+ break;
+
+ default:
+ panic("Unhandled reloc type %u\n", type);
+ }
+}
+
+/**
+ * relocate_code() - Relocate Barebox, generally from flash to DDR
+ * @start_addr_sp: new stack pointer
+ * @new_gd: pointer to relocated global data
+ * @relocaddr: the address to relocate to
+ *
+ * Relocate Barebox from its current location (generally in flash) to a new one
+ * (generally in DDR). This function will copy the Barebox binary & apply
+ * relocations as necessary, then jump to board_init_r in the new build of
+ * Barebox. As such, this function does not return.
+ */
+void relocate_code(void *fdt, u32 fdt_size, u32 ram_size)
+{
+ unsigned long addr, length, bss_len;
+ u32 relocaddr, new_stack;
+ uint8_t *buf, *bss_start;
+ unsigned int type;
+ long off;
+
+ length = barebox_image_size + MAX_BSS_SIZE;
+ relocaddr = ALIGN_DOWN(ram_size - barebox_image_size, SZ_64K);
+ relocaddr = KSEG0ADDR(relocaddr);
+ new_stack = relocaddr - MALLOC_SIZE - 16;
+
+ /*
+ * Ensure that we're relocating by an offset which is a multiple of
+ * 64KiB, ie. doesn't change the least significant 16 bits of any
+ * addresses. This allows us to discard R_MIPS_LO16 relocs, saving
+ * space in the Barebox binary & complexity in handling them.
+ */
+ off = relocaddr - (unsigned long)__image_start;
+ if (off & 0xffff)
+ panic("Mis-aligned relocation\n");
+
+ /* Copy Barebox to RAM */
+ memcpy((void *)relocaddr, __image_start, length);
+
+ /* Now apply relocations to the copy in RAM */
+ buf = __rel_start;
+ addr = relocaddr;
+ while (true) {
+ type = read_uint(&buf);
+ if (type == R_MIPS_NONE)
+ break;
+
+ addr += read_uint(&buf) << 2;
+ apply_reloc(type, (void *)addr, off);
+ }
+
+ /* Ensure the icache is coherent */
+ flush_cache_all();
+
+ /* Clear the .bss section */
+ bss_start = (uint8_t *)((unsigned long)__bss_start + off);
+ bss_len = (unsigned long)&__bss_stop - (unsigned long)__bss_start;
+ memset(bss_start, 0, bss_len);
+
+ __asm__ __volatile__ (
+ "move $a0, %0\n"
+ " move $a1, %1\n"
+ " move $31, $0\n"
+ " move $sp, %2\n"
+ " jr %3\n"
+ : /* no outputs */
+ : "r"(fdt),
+ "r"(fdt_size),
+ "r"(new_stack),
+ "r"((unsigned long)main_entry + off));
+
+ /* Since we jumped to the new Barebox above, we won't get here */
+ unreachable();
+}
diff --git a/arch/mips/lib/sections.c b/arch/mips/lib/sections.c
new file mode 100644
index 0000000000..66d559f94a
--- /dev/null
+++ b/arch/mips/lib/sections.c
@@ -0,0 +1,9 @@
+#include <common.h>
+#include <asm/sections.h>
+#include <linux/types.h>
+
+char _text[0] __attribute__((section("._text")));
+char __bss_start[0] __attribute__((section(".__bss_start")));
+char __bss_stop[0] __attribute__((section(".__bss_stop")));
+char __image_start[0] __attribute__((section(".__image_start")));
+char __image_end[0] __attribute__((section(".__image_end")));
diff --git a/scripts/Makefile b/scripts/Makefile
index ff0a3c2a07..62d4ab20aa 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -12,6 +12,7 @@ hostprogs-y += bareboxcrc32
hostprogs-y += kernel-install
hostprogs-$(CONFIG_IMD) += bareboximd
hostprogs-$(CONFIG_KALLSYMS) += kallsyms
+hostprogs-$(CONFIG_MIPS) += mips-relocs
hostprogs-$(CONFIG_MVEBU_HOSTTOOLS) += kwbimage kwboot
hostprogs-$(CONFIG_ARCH_NETX) += gen_netx_image
hostprogs-$(CONFIG_ARCH_OMAP) += omap_signGP mk-omap-image
diff --git a/scripts/mips-relocs.c b/scripts/mips-relocs.c
new file mode 100644
index 0000000000..7916159581
--- /dev/null
+++ b/scripts/mips-relocs.c
@@ -0,0 +1,426 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * MIPS Relocation Data Generator
+ *
+ * Copyright (c) 2017 Imagination Technologies Ltd.
+ */
+
+#include <assert.h>
+#include <elf.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <../../arch/mips/include/asm/relocs.h>
+
+#define hdr_field(pfx, idx, field) ({ \
+ uint64_t _val; \
+ unsigned int _size; \
+ \
+ if (is_64) { \
+ _val = pfx##hdr64[idx].field; \
+ _size = sizeof(pfx##hdr64[0].field); \
+ } else { \
+ _val = pfx##hdr32[idx].field; \
+ _size = sizeof(pfx##hdr32[0].field); \
+ } \
+ \
+ switch (_size) { \
+ case 1: \
+ break; \
+ case 2: \
+ _val = is_be ? be16toh(_val) : le16toh(_val); \
+ break; \
+ case 4: \
+ _val = is_be ? be32toh(_val) : le32toh(_val); \
+ break; \
+ case 8: \
+ _val = is_be ? be64toh(_val) : le64toh(_val); \
+ break; \
+ } \
+ \
+ _val; \
+})
+
+#define set_hdr_field(pfx, idx, field, val) ({ \
+ uint64_t _val; \
+ unsigned int _size; \
+ \
+ if (is_64) \
+ _size = sizeof(pfx##hdr64[0].field); \
+ else \
+ _size = sizeof(pfx##hdr32[0].field); \
+ \
+ switch (_size) { \
+ case 1: \
+ _val = val; \
+ break; \
+ case 2: \
+ _val = is_be ? htobe16(val) : htole16(val); \
+ break; \
+ case 4: \
+ _val = is_be ? htobe32(val) : htole32(val); \
+ break; \
+ case 8: \
+ _val = is_be ? htobe64(val) : htole64(val); \
+ break; \
+ default: \
+ /* We should never reach here */ \
+ _val = 0; \
+ assert(0); \
+ break; \
+ } \
+ \
+ if (is_64) \
+ pfx##hdr64[idx].field = _val; \
+ else \
+ pfx##hdr32[idx].field = _val; \
+})
+
+#define ehdr_field(field) \
+ hdr_field(e, 0, field)
+#define phdr_field(idx, field) \
+ hdr_field(p, idx, field)
+#define shdr_field(idx, field) \
+ hdr_field(s, idx, field)
+
+#define set_phdr_field(idx, field, val) \
+ set_hdr_field(p, idx, field, val)
+#define set_shdr_field(idx, field, val) \
+ set_hdr_field(s, idx, field, val)
+
+#define shstr(idx) (&shstrtab[idx])
+
+bool is_64, is_be;
+uint64_t text_base;
+
+struct mips_reloc {
+ uint8_t type;
+ uint64_t offset;
+} *relocs;
+size_t relocs_sz, relocs_idx;
+
+static int add_reloc(unsigned int type, uint64_t off)
+{
+ struct mips_reloc *new;
+ size_t new_sz;
+
+ switch (type) {
+ case R_MIPS_NONE:
+ case R_MIPS_LO16:
+ case R_MIPS_PC16:
+ case R_MIPS_HIGHER:
+ case R_MIPS_HIGHEST:
+ case R_MIPS_PC21_S2:
+ case R_MIPS_PC26_S2:
+ /* Skip these relocs */
+ return 0;
+
+ default:
+ break;
+ }
+
+ if (relocs_idx == relocs_sz) {
+ new_sz = relocs_sz ? relocs_sz * 2 : 128;
+ new = realloc(relocs, new_sz * sizeof(*relocs));
+ if (!new) {
+ fprintf(stderr, "Out of memory\n");
+ return -ENOMEM;
+ }
+
+ relocs = new;
+ relocs_sz = new_sz;
+ }
+
+ relocs[relocs_idx++] = (struct mips_reloc){
+ .type = type,
+ .offset = off,
+ };
+
+ return 0;
+}
+
+static int parse_mips32_rel(const void *_rel)
+{
+ const Elf32_Rel *rel = _rel;
+ uint32_t off, type;
+
+ off = is_be ? be32toh(rel->r_offset) : le32toh(rel->r_offset);
+ off -= text_base;
+
+ type = is_be ? be32toh(rel->r_info) : le32toh(rel->r_info);
+ type = ELF32_R_TYPE(type);
+
+ return add_reloc(type, off);
+}
+
+static int parse_mips64_rela(const void *_rel)
+{
+ const Elf64_Rela *rel = _rel;
+ uint64_t off, type;
+
+ off = is_be ? be64toh(rel->r_offset) : le64toh(rel->r_offset);
+ off -= text_base;
+
+ type = rel->r_info >> (64 - 8);
+
+ return add_reloc(type, off);
+}
+
+static void output_uint(uint8_t **buf, uint64_t val)
+{
+ uint64_t tmp;
+
+ do {
+ tmp = val & 0x7f;
+ val >>= 7;
+ tmp |= !!val << 7;
+ *(*buf)++ = tmp;
+ } while (val);
+}
+
+static int compare_relocs(const void *a, const void *b)
+{
+ const struct mips_reloc *ra = a, *rb = b;
+
+ return ra->offset - rb->offset;
+}
+
+int main(int argc, char *argv[])
+{
+ unsigned int i, j, i_rel_shdr, sh_type, sh_entsize, sh_entries;
+ size_t rel_size, rel_actual_size;
+ const char *shstrtab, *sh_name, *rel_pfx;
+ int (*parse_fn)(const void *rel);
+ uint8_t *buf_start, *buf;
+ const Elf32_Ehdr *ehdr32;
+ const Elf64_Ehdr *ehdr64;
+ uintptr_t sh_offset;
+ Elf32_Shdr *shdr32;
+ Elf64_Shdr *shdr64;
+ struct stat st;
+ int err, fd;
+ void *elf;
+ bool skip;
+
+ fd = open(argv[1], O_RDWR);
+ if (fd == -1) {
+ fprintf(stderr, "Unable to open input file %s\n", argv[1]);
+ err = errno;
+ goto out_ret;
+ }
+
+ err = fstat(fd, &st);
+ if (err) {
+ fprintf(stderr, "Unable to fstat() input file\n");
+ goto out_close_fd;
+ }
+
+ elf = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+ if (elf == MAP_FAILED) {
+ fprintf(stderr, "Unable to mmap() input file\n");
+ err = errno;
+ goto out_close_fd;
+ }
+
+ ehdr32 = elf;
+ ehdr64 = elf;
+
+ if (memcmp(&ehdr32->e_ident[EI_MAG0], ELFMAG, SELFMAG)) {
+ fprintf(stderr, "Input file is not an ELF\n");
+ err = -EINVAL;
+ goto out_free_relocs;
+ }
+
+ if (ehdr32->e_ident[EI_VERSION] != EV_CURRENT) {
+ fprintf(stderr, "Unrecognised ELF version\n");
+ err = -EINVAL;
+ goto out_free_relocs;
+ }
+
+ switch (ehdr32->e_ident[EI_CLASS]) {
+ case ELFCLASS32:
+ is_64 = false;
+ break;
+ case ELFCLASS64:
+ is_64 = true;
+ break;
+ default:
+ fprintf(stderr, "Unrecognised ELF class\n");
+ err = -EINVAL;
+ goto out_free_relocs;
+ }
+
+ switch (ehdr32->e_ident[EI_DATA]) {
+ case ELFDATA2LSB:
+ is_be = false;
+ break;
+ case ELFDATA2MSB:
+ is_be = true;
+ break;
+ default:
+ fprintf(stderr, "Unrecognised ELF data encoding\n");
+ err = -EINVAL;
+ goto out_free_relocs;
+ }
+
+ if (ehdr_field(e_type) != ET_EXEC) {
+ fprintf(stderr, "Input ELF is not an executable\n");
+ printf("type 0x%lx\n", ehdr_field(e_type));
+ err = -EINVAL;
+ goto out_free_relocs;
+ }
+
+ if (ehdr_field(e_machine) != EM_MIPS) {
+ fprintf(stderr, "Input ELF does not target MIPS\n");
+ err = -EINVAL;
+ goto out_free_relocs;
+ }
+
+ shdr32 = elf + ehdr_field(e_shoff);
+ shdr64 = elf + ehdr_field(e_shoff);
+ shstrtab = elf + shdr_field(ehdr_field(e_shstrndx), sh_offset);
+
+ i_rel_shdr = UINT_MAX;
+ for (i = 0; i < ehdr_field(e_shnum); i++) {
+ sh_name = shstr(shdr_field(i, sh_name));
+
+ if (!strcmp(sh_name, ".data.reloc")) {
+ i_rel_shdr = i;
+ continue;
+ }
+
+ if (!strcmp(sh_name, ".text")) {
+ text_base = shdr_field(i, sh_addr);
+ continue;
+ }
+ }
+ if (i_rel_shdr == UINT_MAX) {
+ fprintf(stderr, "Unable to find .rel section\n");
+ err = -EINVAL;
+ goto out_free_relocs;
+ }
+ if (!text_base) {
+ fprintf(stderr, "Unable to find .text base address\n");
+ err = -EINVAL;
+ goto out_free_relocs;
+ }
+
+ rel_pfx = is_64 ? ".rela." : ".rel.";
+
+ for (i = 0; i < ehdr_field(e_shnum); i++) {
+ sh_type = shdr_field(i, sh_type);
+ if ((sh_type != SHT_REL) && (sh_type != SHT_RELA))
+ continue;
+
+ sh_name = shstr(shdr_field(i, sh_name));
+ if (strncmp(sh_name, rel_pfx, strlen(rel_pfx))) {
+ if (strcmp(sh_name, ".rel") && strcmp(sh_name, ".rel.dyn"))
+ fprintf(stderr, "WARNING: Unexpected reloc section name '%s'\n", sh_name);
+ continue;
+ }
+
+ /*
+ * Skip reloc sections which either don't correspond to another
+ * section in the ELF, or whose corresponding section isn't
+ * loaded as part of the U-Boot binary (ie. doesn't have the
+ * alloc flags set).
+ */
+ skip = true;
+ for (j = 0; j < ehdr_field(e_shnum); j++) {
+ if (strcmp(&sh_name[strlen(rel_pfx) - 1], shstr(shdr_field(j, sh_name))))
+ continue;
+
+ skip = !(shdr_field(j, sh_flags) & SHF_ALLOC);
+ break;
+ }
+ if (skip)
+ continue;
+
+ sh_offset = shdr_field(i, sh_offset);
+ sh_entsize = shdr_field(i, sh_entsize);
+ sh_entries = shdr_field(i, sh_size) / sh_entsize;
+
+ if (sh_type == SHT_REL) {
+ if (is_64) {
+ fprintf(stderr, "REL-style reloc in MIPS64 ELF?\n");
+ err = -EINVAL;
+ goto out_free_relocs;
+ } else {
+ parse_fn = parse_mips32_rel;
+ }
+ } else {
+ if (is_64) {
+ parse_fn = parse_mips64_rela;
+ } else {
+ fprintf(stderr, "RELA-style reloc in MIPS32 ELF?\n");
+ err = -EINVAL;
+ goto out_free_relocs;
+ }
+ }
+
+ for (j = 0; j < sh_entries; j++) {
+ err = parse_fn(elf + sh_offset + (j * sh_entsize));
+ if (err)
+ goto out_free_relocs;
+ }
+ }
+
+ if (!relocs) {
+ fprintf(stderr, "No relocs was found. Try to configure linker with --emit-relocs\n");
+ err = -EINVAL;
+ goto out_free_relocs;
+ }
+
+ /* Sort relocs in ascending order of offset */
+ qsort(relocs, relocs_idx, sizeof(*relocs), compare_relocs);
+
+ /* Make reloc offsets relative to their predecessor */
+ for (i = relocs_idx - 1; i > 0; i--) {
+ relocs[i].offset -= relocs[i - 1].offset;
+ }
+
+ /* Write the relocations to the .rel section */
+ buf = buf_start = elf + shdr_field(i_rel_shdr, sh_offset);
+ for (i = 0; i < relocs_idx; i++) {
+ output_uint(&buf, relocs[i].type);
+ output_uint(&buf, relocs[i].offset >> 2);
+ }
+
+ /* Write a terminating R_MIPS_NONE (0) */
+ output_uint(&buf, R_MIPS_NONE);
+
+ /* Ensure the relocs didn't overflow the .rel section */
+ rel_size = shdr_field(i_rel_shdr, sh_size);
+ rel_actual_size = buf - buf_start;
+ if (rel_actual_size > rel_size) {
+ fprintf(stderr, "Relocations overflow available space of 0x%lx (required 0x%lx)!\n",
+ rel_size, rel_actual_size);
+ fprintf(stderr, "Please adjust CONFIG_MIPS_RELOCATION_TABLE_SIZE to at least 0x%lx\n",
+ (rel_actual_size + 0x100) & ~0xFF);
+ err = -ENOMEM;
+ goto out_free_relocs;
+ }
+
+ /* Make sure data is written back to the file */
+ err = msync(elf, st.st_size, MS_SYNC);
+ if (err) {
+ fprintf(stderr, "Failed to msync: %d\n", errno);
+ goto out_free_relocs;
+ }
+
+out_free_relocs:
+ free(relocs);
+ munmap(elf, st.st_size);
+out_close_fd:
+ close(fd);
+out_ret:
+ return err;
+}
--
2.20.1
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