diff options
| author | Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> | 2015-11-04 17:08:37 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-11-16 18:34:38 +0000 |
| commit | a4124e7296000242243996e1ae2601cfadf276a5 (patch) | |
| tree | 93b53a9c4bedc358c6c53ec0a7b98344bf612c53 /arch/arm/mm | |
| parent | 440ee365d30adbcd9a97fba9cd629cedb7e9b7cb (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-König <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>
Diffstat (limited to 'arch/arm/mm')
| -rw-r--r-- | arch/arm/mm/proc-v7m.S | 14 |
1 files changed, 5 insertions, 9 deletions
diff --git a/arch/arm/mm/proc-v7m.S b/arch/arm/mm/proc-v7m.S index 67d9209077c6..7229d8d0be1a 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" |