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authorEzequiel Garcia <ezequiel@vanguardiasur.com.ar>2015-11-04 17:08:37 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2015-11-16 18:34:38 +0000
commita4124e7296000242243996e1ae2601cfadf276a5 (patch)
tree93b53a9c4bedc358c6c53ec0a7b98344bf612c53
parent440ee365d30adbcd9a97fba9cd629cedb7e9b7cb (diff)
ARM: 8451/1: v7-M: Set an early stack for __v7m_setup
On ARM v7-M, when PROCINFO_INITFUNC (__v7m_setup) is called, a stack is needed before calling the supervisor call (SVC), which is used by the supervisor call to save the context. Currently, __v7m_setup() prepares a temporary stack in the .text.init section, which is is broken if the kernel is executing directly from read-only memory. In particular, this is the case for LPC43xx, which allows to execute the kernel in-place from a serial flash through its SPIFI controller. This commit fixes the issue by seting an early stack to its usual location. Also, __v7m_setup() is currently saving and restoring the previous stack. That was bogus, because there's no stack previously set, so this commit removes it. Acked-by: Uwe Kleine-K├Ânig <u.kleine-koenig@pengutronix.de> Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--arch/arm/mm/proc-v7m.S14
1 files changed, 5 insertions, 9 deletions
diff --git a/arch/arm/mm/proc-v7m.S b/arch/arm/mm/proc-v7m.S
index 67d9209..7229d8d 100644
--- a/arch/arm/mm/proc-v7m.S
+++ b/arch/arm/mm/proc-v7m.S
@@ -12,6 +12,7 @@
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
+#include <asm/memory.h>
#include <asm/v7m.h>
#include "proc-macros.S"
@@ -97,19 +98,19 @@ __v7m_setup:
mov r5, #0x00800000
str r5, [r0, V7M_SCB_SHPR3] @ set PendSV priority
- @ SVC to run the kernel in this mode
+ @ SVC to switch to handler mode. Notice that this requires sp to
+ @ point to writeable memory because the processor saves
+ @ some registers to the stack.
badr r1, 1f
ldr r5, [r12, #11 * 4] @ read the SVC vector entry
str r1, [r12, #11 * 4] @ write the temporary SVC vector entry
mov r6, lr @ save LR
- mov r7, sp @ save SP
- ldr sp, =__v7m_setup_stack_top
+ ldr sp, =init_thread_union + THREAD_START_SP
cpsie i
svc #0
1: cpsid i
str r5, [r12, #11 * 4] @ restore the original SVC vector entry
mov lr, r6 @ restore LR
- mov sp, r7 @ restore SP
@ Special-purpose control register
mov r1, #1
@@ -123,11 +124,6 @@ __v7m_setup:
ret lr
ENDPROC(__v7m_setup)
- .align 2
-__v7m_setup_stack:
- .space 4 * 8 @ 8 registers
-__v7m_setup_stack_top:
-
define_processor_functions v7m, dabort=nommu_early_abort, pabort=legacy_pabort, nommu=1
.section ".rodata"