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| author | Ahmad Fatoum <a.fatoum@pengutronix.de> | 2024-03-04 19:59:41 +0100 |
|---|---|---|
| committer | Sascha Hauer <s.hauer@pengutronix.de> | 2024-03-05 16:28:05 +0100 |
| commit | 0bfc6ab8bc6599720b9aab04ee1b138b96f7e6d2 (patch) | |
| tree | 9d79a55314e17fd99c720f5e1eaf9bc299aa3813 /arch/arm/cpu/setupc_64.S | |
| parent | 62a782bb02f53c6eadad31d5031a073184b7accb (diff) | |
| download | barebox-0bfc6ab8bc6599720b9aab04ee1b138b96f7e6d2.tar.gz barebox-0bfc6ab8bc6599720b9aab04ee1b138b96f7e6d2.tar.xz | |
ARM64: cpu: setupc: rewrite to be fully PIC
The code resulting from building the barebox ARM64 assembly contains
relocations, which could've been position-independent just as well.
Let's make them truly position independent by turning:
ldr x0, =label
into
adr_l x0, label
adr_l is position independent by virtue of being implemented using adrp,
so it's usuable as-is before relocation and requires no manual addition
of get_runtime_offset().
With these changes, only relocation necessary for the ARM64 generic DT
2nd stage is the one needed for get_runtime_offset() to find out
whether barebox has been relocated.
This is one step towards supporting mapping barebox PBL text section
W^X, which precludes relocation entries emitted for code.
With this change applied, there is still a data relocation entry
in assembly code for get_runtime_offset(), but that doesn't bother us
because it's in the data section.
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20240304190038.3486881-57-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'arch/arm/cpu/setupc_64.S')
| -rw-r--r-- | arch/arm/cpu/setupc_64.S | 22 |
1 files changed, 9 insertions, 13 deletions
diff --git a/arch/arm/cpu/setupc_64.S b/arch/arm/cpu/setupc_64.S index f38f893be9..2138c2a600 100644 --- a/arch/arm/cpu/setupc_64.S +++ b/arch/arm/cpu/setupc_64.S @@ -1,6 +1,7 @@ /* SPDX-License-Identifier: GPL-2.0-only */ #include <linux/linkage.h> +#include <asm/assembler.h> #include <asm/sections.h> .section .text.setupc @@ -10,9 +11,9 @@ */ ENTRY(setup_c) mov x15, x30 - ldr x0, =__bss_start + adr_l x0, __bss_start mov x1, #0 - ldr x2, =__bss_stop + adr_l x2, __bss_stop sub x2, x2, x0 bl __memset /* clear bss */ mov x30, x15 @@ -29,12 +30,12 @@ ENDPROC(setup_c) /* x0: target address */ #ifdef __PBL__ ENTRY(relocate_to_adr_full) - ldr x2, =__image_end + adr_l x2, __image_end b 1f #endif ENTRY(relocate_to_adr) - ldr x2, =__bss_start + adr_l x2, __bss_start b 1f 1: @@ -45,18 +46,13 @@ ENTRY(relocate_to_adr) mov x21, x0 - bl get_runtime_offset - mov x5, x0 - - ldr x0, =_text - mov x20, x0 - - add x1, x0, x5 /* x1: from address */ + adr_l x1, _text + mov x20, x1 cmp x1, x21 /* already at correct address? */ beq 1f /* yes, skip copy to new address */ - sub x2, x2, x0 /* x2: size */ + sub x2, x2, x1 /* x2: size */ mov x0, x21 /* x0: target */ /* adjust return address */ @@ -70,7 +66,7 @@ ENTRY(relocate_to_adr) mov x0,#0 ic ivau, x0 /* flush icache */ - ldr x0,=1f + adr_l x0, 1f sub x0, x0, x20 add x0, x0, x21 br x0 /* jump to relocated address */ |