[U-Boot] [RFC 0/3] MIPS: add automatic relocation support
This series adds dynamic relocation support for MIPS. The patches are against the testing branch of the MIPS custodian tree.
The patch-set depends on the following patches:
http://patchwork.ozlabs.org/patch/214352/ (malloc: make malloc_bin_reloc static)
http://patchwork.ozlabs.org/patch/217651/ (MIPS: compute num_got_entries from .got section's size)
Gabor Juhos (3): MIPS: add .dyn.rel section to u-boot.lds MIPS: add -pie flag to LDFLAGS_FINAL MIPS: add dynamic relocation support
arch/mips/config.mk | 2 +- arch/mips/cpu/mips32/start.S | 31 +++++++++++++++++++++++++++++-- arch/mips/cpu/mips64/start.S | 39 +++++++++++++++++++++++++++++++++++++-- arch/mips/cpu/u-boot.lds | 27 ++++++++++++++++++++++++++- arch/mips/cpu/xburst/start.S | 31 +++++++++++++++++++++++++++++-- arch/mips/include/asm/config.h | 2 -- 6 files changed, 122 insertions(+), 10 deletions(-)
-- 1.7.10
This section contain the table needed for dynamic relocation. Also provide symbols for the relocation code to access the table.
Signed-off-by: Gabor Juhos juhosg@openwrt.org Cc: Daniel Schwierzeck daniel.schwierzeck@googlemail.com --- arch/mips/cpu/u-boot.lds | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-)
diff --git a/arch/mips/cpu/u-boot.lds b/arch/mips/cpu/u-boot.lds index 58a49b2..3d9d82a 100644 --- a/arch/mips/cpu/u-boot.lds +++ b/arch/mips/cpu/u-boot.lds @@ -70,11 +70,36 @@ SECTIONS uboot_end_data = .;
. = ALIGN(4); + .rel.dyn : { + __rel_dyn_start = .; + *(.rel*) + __rel_dyn_end = .; + } + + .deadcode : { + /* + * Workaround for a binutils feature (or bug?). + * + * The GNU ld from binutils puts the dynamic relocation + * entries into the .rel.dyn section. Sometimes it + * allocates more dynamic relocation entries than it needs + * and the unused slots are set to R_MIPS_NONE entries. + * + * However the size of the .rel.dyn section in the ELF + * section header does not cover the unused entries, so + * objcopy removes those during stripping. + * + * Create a small section here to avoid that. + */ + LONG(0xffffffff); + } + + . = ALIGN(4); .sbss : { *(.sbss*) }
- .bss : { + .bss __rel_dyn_start (OVERLAY) : { *(.bss*) . = ALIGN(4); }
This ensures that the linker generates the .rel.dyn fixup table, which will be applied to the relocated image before transferring control to it.
Signed-off-by: Gabor Juhos juhosg@openwrt.org Cc: Daniel Schwierzeck daniel.schwierzeck@googlemail.com --- arch/mips/config.mk | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/config.mk b/arch/mips/config.mk index de9140b..57f2338 100644 --- a/arch/mips/config.mk +++ b/arch/mips/config.mk @@ -65,4 +65,4 @@ PLATFORM_CPPFLAGS += -G 0 -mabicalls -fpic $(ENDIANNESS) PLATFORM_CPPFLAGS += -msoft-float PLATFORM_LDFLAGS += -G 0 -static -n -nostdlib $(ENDIANNESS) PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections -LDFLAGS_FINAL += --gc-sections +LDFLAGS_FINAL += --gc-sections -pie
The code handles relocation entries with the following relocation types only: mips32: R_MIPS_REL32 mips64: R_MIPS_REL+R_MIPS_64 xburst: R_MIPS_REL32
Other relocation entries are skipped without processing. The code must be extended if other relocation types must be upported, however my toolchains uses these types only.
The CONFIG_NEEDS_MANUAL_RELOC is not needed after the patch, so remove that as well.
Signed-off-by: Gabor Juhos juhosg@openwrt.org Cc: Daniel Schwierzeck daniel.schwierzeck@googlemail.com --- arch/mips/cpu/mips32/start.S | 31 +++++++++++++++++++++++++++++-- arch/mips/cpu/mips64/start.S | 39 +++++++++++++++++++++++++++++++++++++-- arch/mips/cpu/xburst/start.S | 31 +++++++++++++++++++++++++++++-- arch/mips/include/asm/config.h | 2 -- 4 files changed, 95 insertions(+), 8 deletions(-)
diff --git a/arch/mips/cpu/mips32/start.S b/arch/mips/cpu/mips32/start.S index 7373d4e..4db06a0 100644 --- a/arch/mips/cpu/mips32/start.S +++ b/arch/mips/cpu/mips32/start.S @@ -201,6 +201,8 @@ relocate_code: jr t0 nop
+ .word __rel_dyn_end + .word __rel_dyn_start .word _GLOBAL_OFFSET_TABLE_ .word uboot_end_data .word uboot_end @@ -228,11 +230,36 @@ in_ram: blt t2, t3, 1b addi t4, 4
+ /* Update dynamic relocations. */ + lw t1, -20(t0) # t1 <-- __rel_dyn_start + lw t2, -24(t0) # t2 <-- __rel_dyn_end + + /* The first relocation entry is reserved, skip it. */ + b 2f + addi t1, 8 + +1: + lw t3, -4(t1) # t4 <-- relocation info + + sub t3, 3 + bnez t3, 2f # skip non R_MIPS_REL32 entries + nop + + lw t3, -8(t1) # t3 <-- location to fix up in FLASH + + lw t4, 0(t3) # t4 <-- original pointer + add t4, s1 # t4 <-- adjusted pointer + + add t3, s1 # t3 <-- location to fix up in RAM + sw t4, 0(t3) + +2: + blt t1, t2, 1b + addi t1, 8 # each rel.dyn entry is 8 bytes + /* Clear BSS */ lw t1, -12(t0) # t1 <-- uboot_end_data lw t2, -8(t0) # t2 <-- uboot_end - add t1, s1 # adjust pointers - add t2, s1
sub t1, 4 1: diff --git a/arch/mips/cpu/mips64/start.S b/arch/mips/cpu/mips64/start.S index c0ae41a..3479d77 100644 --- a/arch/mips/cpu/mips64/start.S +++ b/arch/mips/cpu/mips64/start.S @@ -31,6 +31,14 @@ #define CONFIG_SYS_MIPS_CACHE_MODE CONF_CM_CACHABLE_NONCOHERENT #endif
+#ifdef CONFIG_SYS_LITTLE_ENDIAN +#define MIPS64_R_INFO(ssym, r_type3, r_type2, r_type) \ + (((r_type) << 24) | ((r_type2) << 16) | ((r_type3) << 8) | (ssym)) +#else +#define MIPS64_R_INFO(ssym, r_type3, r_type2, r_type) \ + ((r_type) | ((r_type2) << 8) | ((r_type3) << 16) | (ssym) << 24) +#endif + /* * For the moment disable interrupts, mark the kernel mode and * set ST0_KX so that the CPU does not spit fire when using @@ -193,6 +201,8 @@ relocate_code: jr t0 nop
+ .dword __rel_dyn_end + .dword __rel_dyn_start .dword _GLOBAL_OFFSET_TABLE_ .dword uboot_end_data .dword uboot_end @@ -220,11 +230,36 @@ in_ram: blt t2, t3, 1b daddi t8, 8
+ /* update dynamic relocation entries */ + ld t1, -40(t0) # t1 <-- __rel_dyn_start + ld t2, -48(t0) # t2 <-- __rel_dyn_end + + /* The first relocation entry is reserved, skip it. */ + b 2f + daddi t1, 16 + +1: + lw t8, -4(t1) # t8 <-- r_info + + dli t3, MIPS64_R_INFO(0x00, 0x00, 0x12, 0x03) + bne t8, t3, 2f # skip non R_MIPS_REL32 entries + nop + + ld t3, -16(t1) # t3 <-- location to fix up in FLASH + + ld t8, 0(t3) # t8 <-- original pointer + dadd t8, s1 # t8 <-- adjusted pointer + + dadd t3, s1 # t3 <-- location to fix up in RAM + sd t8, 0(t3) + +2: + blt t1, t2, 1b + daddi t1, 16 # each rel.dyn entry is 16 bytes + /* Clear BSS */ ld t1, -24(t0) # t1 <-- uboot_end_data ld t2, -16(t0) # t2 <-- uboot_end - dadd t1, s1 # adjust pointers - dadd t2, s1
dsub t1, 8 1: diff --git a/arch/mips/cpu/xburst/start.S b/arch/mips/cpu/xburst/start.S index 50b7fb1..e669061 100644 --- a/arch/mips/cpu/xburst/start.S +++ b/arch/mips/cpu/xburst/start.S @@ -116,6 +116,8 @@ relocate_code: jr t0 nop
+ .word __rel_dyn_end + .word __rel_dyn_start .word _GLOBAL_OFFSET_TABLE_ .word uboot_end_data .word uboot_end @@ -143,11 +145,36 @@ in_ram: blt t2, t3, 1b addi t4, 4
+ /* Update dynamic relocations. */ + lw t1, -20(t0) # t1 <-- __rel_dyn_start + lw t2, -24(t0) # t2 <-- __rel_dyn_end + + /* The first relocation entry is reserved, skip it. */ + b 2f + addi t1, 8 + +1: + lw t3, -4(t1) # t4 <-- relocation info + + sub t3, 3 + bnez t3, 2f # skip non R_MIPS_REL32 entries + nop + + lw t3, -8(t1) # t3 <-- location to fix up in FLASH + + lw t4, 0(t3) # t4 <-- original pointer + add t4, t6 # t4 <-- adjusted pointer + + add t3, t6 # t3 <-- location to fix up in RAM + sw t4, 0(t3) + +2: + blt t1, t2, 1b + addi t1, 8 # each rel.dyn entry is 8 bytes + /* Clear BSS */ lw t1, -12(t0) # t1 <-- uboot_end_data lw t2, -8(t0) # t2 <-- uboot_end - add t1, t6 # adjust pointers - add t2, t6
sub t1, 4 1: addi t1, 4 diff --git a/arch/mips/include/asm/config.h b/arch/mips/include/asm/config.h index 02fbfb3..049c44e 100644 --- a/arch/mips/include/asm/config.h +++ b/arch/mips/include/asm/config.h @@ -21,6 +21,4 @@ #ifndef _ASM_CONFIG_H_ #define _ASM_CONFIG_H_
-#define CONFIG_NEEDS_MANUAL_RELOC - #endif
participants (1)
-
Gabor Juhos