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 | 3 +-- arch/arm/cpu/mmu_32.c | 5 +++-- 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 ++++ 7 files changed, 33 insertions(+), 17 deletions(-) diff --git a/arch/arm/cpu/exceptions_32.S b/arch/arm/cpu/exceptions_32.S index 235996f7ec296b44261637bc98c1c5ee30a3cbe1..302e4d030d6347e8fdb488db73a0a3a4bb1c0ec7 100644 --- a/arch/arm/cpu/exceptions_32.S +++ b/arch/arm/cpu/exceptions_32.S @@ -156,6 +156,26 @@ 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 185646e38195b2bdc9f0d7e30d53a0506932fa13..6ebcbcd8dc1299c0333da87e496bc57172691fa8 100644 --- a/arch/arm/cpu/interrupts_32.c +++ b/arch/arm/cpu/interrupts_32.c @@ -181,7 +181,6 @@ 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/mmu_32.c b/arch/arm/cpu/mmu_32.c index 86a55d165ba3cec5154c345a1a3a9cb959f0996f..9ce77078d5e35810f2239d82f29f67e2aa2e4d8e 100644 --- a/arch/arm/cpu/mmu_32.c +++ b/arch/arm/cpu/mmu_32.c @@ -629,8 +629,9 @@ void setup_trap_pages(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)) { + pr_debug("Using inplace exception vectors at 0x%08lx\n", + (unsigned long)__inplace_exceptions_start); create_zero_page(); return; } 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 ede6889991f16d00f2bad79dd777ae9b5e639ff4..9b2b65e2f17d62d5134fc367621cce733dcea06a 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
