[PATCH v3 2/9] lpc2k: Exception vector handling
Ithamar R. Adema
ithamar.adema at team-embedded.nl
Sun Mar 20 16:30:02 EDT 2011
The LPC2K optionally remaps the first 64 bytes of SRAM to address 0, to facilitate
writable low vectors. However, since it only remaps the first 64 bytes the stubs
can't be copied there and end up too far away from the vectors, requiring the
vectors to use an indirect jump instead of branch to get to the stubs.
Since now VECTOR_BASE is below PHYS_OFFSET, do not try to reserve the vector
page, as it will fail (and prevent the kernel from booting).
Also, commit 247055aa (6384/1: Remove the domain switching on ARMv6k/v7 CPUs) broke
the placement of vectors in the !MMU case, so fix this too.
Signed-off-by: Ithamar R. Adema <ithamar.adema at team-embedded.nl>
---
changes since v2:
* reworded reason for vector branch changes.
changes since v1:
* added comment to entry-armv.S vector #ifdef.
---
arch/arm/Kconfig | 1 +
arch/arm/kernel/entry-armv.S | 23 +++++++++++++++++++++++
arch/arm/kernel/traps.c | 2 +-
arch/arm/mm/nommu.c | 2 ++
4 files changed, 27 insertions(+), 1 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a74c200..7b5adab 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -186,6 +186,7 @@ config VECTORS_BASE
hex
default 0xffff0000 if MMU || CPU_HIGH_VECTOR
default DRAM_BASE if REMAP_VECTORS_TO_RAM
+ default 0x40000000 if ARCH_LPC2K
default 0x00000000
help
The base address of exception vectors.
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index e8d8856..65be7b1 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -1208,6 +1208,7 @@ __stubs_end:
.globl __vectors_start
__vectors_start:
+#ifndef CONFIG_ARCH_LPC2K
ARM( swi SYS_ERROR0 )
THUMB( svc #0 )
THUMB( nop )
@@ -1218,6 +1219,28 @@ __vectors_start:
W(b) vector_addrexcptn + stubs_offset
W(b) vector_irq + stubs_offset
W(b) vector_fiq + stubs_offset
+#else /* CONFIG_ARCH_LPC2K */
+ /*
+ * The LPC2K remaps 64 bytes of SRAM to address 0 for vectors. This
+ * means that the stubs can't be in the same page, and end up too far
+ * away from the vectors to use a branch instruction.
+ */
+ swi SYS_ERROR0
+ ldr pc, .vector_und
+ ldr pc, .vector_swi
+ ldr pc, .vector_pabt
+ ldr pc, .vector_dabt
+ ldr pc, .vector_addrexcptn
+ ldr pc, .vector_irq
+ ldr pc, .vector_fiq
+.vector_und: .word vector_und
+.vector_swi: .word vector_swi
+.vector_pabt: .word vector_pabt
+.vector_dabt: .word vector_dabt
+.vector_addrexcptn: .word vector_addrexcptn
+.vector_irq: .word vector_irq
+.vector_fiq: .word vector_fiq
+#endif
.globl __vectors_end
__vectors_end:
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 21ac43f..639c4c8 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -758,7 +758,7 @@ static void __init kuser_get_tls_init(unsigned long vectors)
void __init early_trap_init(void)
{
-#if defined(CONFIG_CPU_USE_DOMAINS)
+#if defined(CONFIG_CPU_USE_DOMAINS) || !defined(CONFIG_MMU)
unsigned long vectors = CONFIG_VECTORS_BASE;
#else
unsigned long vectors = (unsigned long)vectors_page;
diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
index 687d023..e3bec02 100644
--- a/arch/arm/mm/nommu.c
+++ b/arch/arm/mm/nommu.c
@@ -24,7 +24,9 @@ void __init arm_mm_memblock_reserve(void)
* some architectures which the DRAM is the exception vector to trap,
* alloc_page breaks with error, although it is not NULL, but "0."
*/
+#if PHYS_OFFSET <= CONFIG_VECTORS_BASE
memblock_reserve(CONFIG_VECTORS_BASE, PAGE_SIZE);
+#endif
}
/*
--
1.7.1
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