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https://source.denx.de/u-boot/u-boot.git
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armv7: Add Position Independent Execution support
A U-Boot image could be loaded and executed at a different location than it was linked at. For example, Aspeed takes a stable release version of U-Boot image as the golden one for recovery purposes. When the primary storage such as flash is corrupted, the golden image would be loaded to any SRAM/DRAM address on demands through ethernet/UART/etc and run for rescue. To deal with this condition, the PIE is needed as there is only one signed, golden image, which could be however executed at different places. This patch adds the PIE support for ARMv7 platform. Signed-off-by: Chia-Wei Wang <chiawei_wang@aspeedtech.com>
This commit is contained in:
Chia-Wei Wang
Tom Rini
parent
aa29b21d62
commit
cd82f19985
@ -11,7 +11,7 @@ config ARM64
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config POSITION_INDEPENDENT
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bool "Generate position-independent pre-relocation code"
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depends on ARM64
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depends on ARM64 || CPU_V7A
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help
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U-Boot expects to be linked to a specific hard-coded address, and to
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be loaded to and run from that address. This option lifts that
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@ -39,6 +39,42 @@ reset:
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/* Allow the board to save important registers */
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b save_boot_params
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save_boot_params_ret:
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#ifdef CONFIG_POSITION_INDEPENDENT
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/*
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* Fix .rela.dyn relocations. This allows U-Boot to loaded to and
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* executed at a different address than it was linked at.
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*/
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pie_fixup:
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adr r0, reset /* r0 <- Runtime value of reset label */
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ldr r1, =reset /* r1 <- Linked value of reset label */
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subs r4, r0, r1 /* r4 <- Runtime-vs-link offset */
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beq pie_fixup_done
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adr r0, pie_fixup
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ldr r1, _rel_dyn_start_ofs
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add r2, r0, r1 /* r2 <- Runtime &__rel_dyn_start */
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ldr r1, _rel_dyn_end_ofs
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add r3, r0, r1 /* r3 <- Runtime &__rel_dyn_end */
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pie_fix_loop:
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ldr r0, [r2] /* r0 <- Link location */
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ldr r1, [r2, #4] /* r1 <- fixup */
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cmp r1, #23 /* relative fixup? */
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bne pie_skip_reloc
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/* relative fix: increase location by offset */
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add r0, r4
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ldr r1, [r0]
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add r1, r4
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str r1, [r0]
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str r0, [r2]
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add r2, #8
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pie_skip_reloc:
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cmp r2, r3
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blo pie_fix_loop
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pie_fixup_done:
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#endif
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#ifdef CONFIG_ARMV7_LPAE
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/*
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* check for Hypervisor support
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@ -340,3 +376,10 @@ ENTRY(cpu_init_crit)
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b lowlevel_init @ go setup pll,mux,memory
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ENDPROC(cpu_init_crit)
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#endif
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#if CONFIG_POSITION_INDEPENDENT
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_rel_dyn_start_ofs:
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.word __rel_dyn_start - pie_fixup
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_rel_dyn_end_ofs:
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.word __rel_dyn_end - pie_fixup
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#endif
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@ -130,6 +130,14 @@ ENTRY(_main)
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ldr r9, [r9, #GD_NEW_GD] /* r9 <- gd->new_gd */
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adr lr, here
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#if defined(CONFIG_POSITION_INDEPENDENT)
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adr r0, _main
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ldr r1, _start_ofs
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add r0, r1
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ldr r1, =CONFIG_SYS_TEXT_BASE
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sub r1, r0
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add lr, r1
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#endif
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ldr r0, [r9, #GD_RELOC_OFF] /* r0 = gd->reloc_off */
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add lr, lr, r0
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#if defined(CONFIG_CPU_V7M)
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@ -180,3 +188,6 @@ here:
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#endif
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ENDPROC(_main)
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_start_ofs:
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.word _start - _main
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@ -78,22 +78,28 @@ ENDPROC(relocate_vectors)
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*/
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ENTRY(relocate_code)
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ldr r1, =__image_copy_start /* r1 <- SRC &__image_copy_start */
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subs r4, r0, r1 /* r4 <- relocation offset */
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beq relocate_done /* skip relocation */
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ldr r2, =__image_copy_end /* r2 <- SRC &__image_copy_end */
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adr r3, relocate_code
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ldr r1, _image_copy_start_ofs
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add r1, r3 /* r1 <- Run &__image_copy_start */
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subs r4, r0, r1 /* r4 <- Run to copy offset */
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beq relocate_done /* skip relocation */
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ldr r1, _image_copy_start_ofs
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add r1, r3 /* r1 <- Run &__image_copy_start */
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ldr r2, _image_copy_end_ofs
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add r2, r3 /* r2 <- Run &__image_copy_end */
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copy_loop:
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ldmia r1!, {r10-r11} /* copy from source address [r1] */
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stmia r0!, {r10-r11} /* copy to target address [r0] */
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cmp r1, r2 /* until source end address [r2] */
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ldmia r1!, {r10-r11} /* copy from source address [r1] */
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stmia r0!, {r10-r11} /* copy to target address [r0] */
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cmp r1, r2 /* until source end address [r2] */
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blo copy_loop
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/*
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* fix .rel.dyn relocations
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*/
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ldr r2, =__rel_dyn_start /* r2 <- SRC &__rel_dyn_start */
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ldr r3, =__rel_dyn_end /* r3 <- SRC &__rel_dyn_end */
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ldr r1, _rel_dyn_start_ofs
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add r2, r1, r3 /* r2 <- Run &__rel_dyn_start */
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ldr r1, _rel_dyn_end_ofs
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add r3, r1, r3 /* r3 <- Run &__rel_dyn_end */
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fixloop:
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ldmia r2!, {r0-r1} /* (r0,r1) <- (SRC location,fixup) */
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and r1, r1, #0xff
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@ -129,3 +135,12 @@ relocate_done:
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#endif
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ENDPROC(relocate_code)
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_image_copy_start_ofs:
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.word __image_copy_start - relocate_code
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_image_copy_end_ofs:
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.word __image_copy_end - relocate_code
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_rel_dyn_start_ofs:
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.word __rel_dyn_start - relocate_code
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_rel_dyn_end_ofs:
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.word __rel_dyn_end - relocate_code
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