Create position-independent exception vectors using relative branches instead of absolute addresses. This works on ARMv7 onwards which supports setting the address of the exception vectors.
New .text_inplace_exceptions section contains PC-relative branches, enabling barebox proper to start with MMU already configured using ELF segment addresses. Signed-off-by: Sascha Hauer <[email protected]> --- arch/arm/cpu/exceptions_32.S | 20 ++++++++++++++++++++ arch/arm/cpu/interrupts_32.c | 7 ++----- arch/arm/cpu/no-mmu.c | 11 +---------- arch/arm/include/asm/sections.h | 1 + arch/arm/lib/pbl.lds.S | 6 +++--- arch/arm/lib32/barebox.lds.S | 4 ++++ 6 files changed, 31 insertions(+), 18 deletions(-) diff --git a/arch/arm/cpu/exceptions_32.S b/arch/arm/cpu/exceptions_32.S index dc3d42663cbedd37947e27d449eb4ac8c3d8c3f1..85ee4ca3fd4e5aff8e1e02aa3d7375173a923072 100644 --- a/arch/arm/cpu/exceptions_32.S +++ b/arch/arm/cpu/exceptions_32.S @@ -155,6 +155,26 @@ ENTRY(arm_fixup_vectors) ENDPROC(arm_fixup_vectors) #endif +.section .text_inplace_exceptions +1: b 1b /* barebox_arm_reset_vector */ +#ifdef CONFIG_ARM_EXCEPTIONS + b undefined_instruction /* undefined instruction */ + b software_interrupt /* software interrupt (SWI) */ + b prefetch_abort /* prefetch abort */ + b data_abort /* data abort */ +1: b 1b /* (reserved) */ + b irq /* irq (interrupt) */ + b fiq /* fiq (fast interrupt) */ +#else +1: b 1b /* undefined instruction */ +1: b 1b /* software interrupt (SWI) */ +1: b 1b /* prefetch abort */ +1: b 1b /* data abort */ +1: b 1b /* (reserved) */ +1: b 1b /* irq (interrupt) */ +1: b 1b /* fiq (fast interrupt) */ +#endif + .section .text_exceptions .globl extable extable: diff --git a/arch/arm/cpu/interrupts_32.c b/arch/arm/cpu/interrupts_32.c index 0b88db10fe487378fe08018701bc672f63139fc1..5dc4802fafbfdbcd54707b84835f40177e10742b 100644 --- a/arch/arm/cpu/interrupts_32.c +++ b/arch/arm/cpu/interrupts_32.c @@ -231,10 +231,8 @@ static __maybe_unused int arm_init_vectors(void) * First try to use the vectors where they actually are, works * on ARMv7 and later. */ - if (!set_vector_table((unsigned long)__exceptions_start)) { - arm_fixup_vectors(); + if (!set_vector_table((unsigned long)__inplace_exceptions_start)) return 0; - } /* * Next try high vectors at 0xffff0000. @@ -264,7 +262,6 @@ void arm_pbl_init_exceptions(void) if (cpu_architecture() < CPU_ARCH_ARMv7) return; - set_vbar((unsigned long)__exceptions_start); - arm_fixup_vectors(); + set_vbar((unsigned long)__inplace_exceptions_start); } #endif diff --git a/arch/arm/cpu/no-mmu.c b/arch/arm/cpu/no-mmu.c index c4ef5d1f9d55136d606c244309dbeeb8fd988784..68246d71156c7c84b9faff452cebb37132b83573 100644 --- a/arch/arm/cpu/no-mmu.c +++ b/arch/arm/cpu/no-mmu.c @@ -21,8 +21,6 @@ #include <asm/sections.h> #include <asm/cputype.h> -#define __exceptions_size (__exceptions_stop - __exceptions_start) - static bool has_vbar(void) { u32 mainid; @@ -41,7 +39,6 @@ static bool has_vbar(void) static int nommu_v7_vectors_init(void) { - void *vectors; u32 cr; if (cpu_architecture() < CPU_ARCH_ARMv7) @@ -58,13 +55,7 @@ static int nommu_v7_vectors_init(void) cr &= ~CR_V; set_cr(cr); - arm_fixup_vectors(); - - vectors = xmemalign(PAGE_SIZE, PAGE_SIZE); - memset(vectors, 0, PAGE_SIZE); - memcpy(vectors, __exceptions_start, __exceptions_size); - - set_vbar((unsigned int)vectors); + set_vbar((unsigned int)__inplace_exceptions_start); return 0; } diff --git a/arch/arm/include/asm/sections.h b/arch/arm/include/asm/sections.h index 15b1a6482a5b148284ab47de2db1c2653909da09..bf4fb7b109a7a22d9a298257af23a11b9efe6861 100644 --- a/arch/arm/include/asm/sections.h +++ b/arch/arm/include/asm/sections.h @@ -13,6 +13,7 @@ extern char __dynsym_start[]; extern char __dynsym_end[]; extern char __exceptions_start[]; extern char __exceptions_stop[]; +extern char __inplace_exceptions_start[]; #endif diff --git a/arch/arm/lib/pbl.lds.S b/arch/arm/lib/pbl.lds.S index 9c51f5eb3a3d8256752a78e03fed851c84d92edb..53b21084cff2e3d916cd37485281f2f78166c37d 100644 --- a/arch/arm/lib/pbl.lds.S +++ b/arch/arm/lib/pbl.lds.S @@ -53,9 +53,9 @@ SECTIONS *(.text_bare_init*) __bare_init_end = .; . = ALIGN(0x20); - __exceptions_start = .; - KEEP(*(.text_exceptions*)) - __exceptions_stop = .; + __inplace_exceptions_start = .; + KEEP(*(.text_inplace_exceptions*)) + __inplace_exceptions_stop = .; *(.text*) } diff --git a/arch/arm/lib32/barebox.lds.S b/arch/arm/lib32/barebox.lds.S index c704dd6d70f3ab157ceb67dfb14760e03f2a5d62..17e0970ba4989e5213ed38ea5ff87bdf5bfa2740 100644 --- a/arch/arm/lib32/barebox.lds.S +++ b/arch/arm/lib32/barebox.lds.S @@ -26,6 +26,10 @@ SECTIONS __exceptions_start = .; KEEP(*(.text_exceptions*)) __exceptions_stop = .; + . = ALIGN(0x20); + __inplace_exceptions_start = .; + KEEP(*(.text_inplace_exceptions*)) + __inplace_exceptions_stop = .; *(.text*) } BAREBOX_BARE_INIT_SIZE -- 2.47.3
