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authorDaniel Thompson <daniel.thompson@linaro.org>2014-09-17 17:12:06 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2014-09-18 00:35:18 +0100
commitc0e7f7ee717e2b4c5791e7422424c96b5008c39e (patch)
treebc04f72e3004ff8873f9cb842fd91c17e35e90d0 /arch/arm/kernel/entry-armv.S
parent9e82bf014195d6f0054982c463575cdce24292be (diff)
downloadlinux-linaro-stable-c0e7f7ee717e2b4c5791e7422424c96b5008c39e.tar.gz
ARM: 8150/3: fiq: Replace default FIQ handler
This patch introduces a new default FIQ handler that is structured in a similar way to the existing ARM exception handler and result in the FIQ being handled by C code running on the SVC stack (despite this code run in the FIQ handler is subject to severe limitations with respect to locking making normal interaction with the kernel impossible). This default handler allows concepts that on x86 would be handled using NMIs to be realized on ARM. Credit: This patch is a near complete re-write of a patch originally provided by Anton Vorontsov. Today only a couple of small fragments survive, however without Anton's work to build from this patch would not exist. Thanks also to Russell King for spoonfeeding me a variety of fixes during the review cycle. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/entry-armv.S')
-rw-r--r--arch/arm/kernel/entry-armv.S98
1 files changed, 87 insertions, 11 deletions
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 36276cdccfbc..859f56cb122b 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -146,7 +146,7 @@ ENDPROC(__und_invalid)
#define SPFIX(code...)
#endif
- .macro svc_entry, stack_hole=0
+ .macro svc_entry, stack_hole=0, trace=1
UNWIND(.fnstart )
UNWIND(.save {r0 - pc} )
sub sp, sp, #(S_FRAME_SIZE + \stack_hole - 4)
@@ -182,9 +182,11 @@ ENDPROC(__und_invalid)
@
stmia r7, {r2 - r6}
+ .if \trace
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_off
#endif
+ .endif
.endm
.align 5
@@ -295,6 +297,15 @@ __pabt_svc:
ENDPROC(__pabt_svc)
.align 5
+__fiq_svc:
+ svc_entry trace=0
+ mov r0, sp @ struct pt_regs *regs
+ bl handle_fiq_as_nmi
+ svc_exit_via_fiq
+ UNWIND(.fnend )
+ENDPROC(__fiq_svc)
+
+ .align 5
.LCcralign:
.word cr_alignment
#ifdef MULTI_DABORT
@@ -305,6 +316,46 @@ ENDPROC(__pabt_svc)
.word fp_enter
/*
+ * Abort mode handlers
+ */
+
+@
+@ Taking a FIQ in abort mode is similar to taking a FIQ in SVC mode
+@ and reuses the same macros. However in abort mode we must also
+@ save/restore lr_abt and spsr_abt to make nested aborts safe.
+@
+ .align 5
+__fiq_abt:
+ svc_entry trace=0
+
+ ARM( msr cpsr_c, #ABT_MODE | PSR_I_BIT | PSR_F_BIT )
+ THUMB( mov r0, #ABT_MODE | PSR_I_BIT | PSR_F_BIT )
+ THUMB( msr cpsr_c, r0 )
+ mov r1, lr @ Save lr_abt
+ mrs r2, spsr @ Save spsr_abt, abort is now safe
+ ARM( msr cpsr_c, #SVC_MODE | PSR_I_BIT | PSR_F_BIT )
+ THUMB( mov r0, #SVC_MODE | PSR_I_BIT | PSR_F_BIT )
+ THUMB( msr cpsr_c, r0 )
+ stmfd sp!, {r1 - r2}
+
+ add r0, sp, #8 @ struct pt_regs *regs
+ bl handle_fiq_as_nmi
+
+ ldmfd sp!, {r1 - r2}
+ ARM( msr cpsr_c, #ABT_MODE | PSR_I_BIT | PSR_F_BIT )
+ THUMB( mov r0, #ABT_MODE | PSR_I_BIT | PSR_F_BIT )
+ THUMB( msr cpsr_c, r0 )
+ mov lr, r1 @ Restore lr_abt, abort is unsafe
+ msr spsr_cxsf, r2 @ Restore spsr_abt
+ ARM( msr cpsr_c, #SVC_MODE | PSR_I_BIT | PSR_F_BIT )
+ THUMB( mov r0, #SVC_MODE | PSR_I_BIT | PSR_F_BIT )
+ THUMB( msr cpsr_c, r0 )
+
+ svc_exit_via_fiq
+ UNWIND(.fnend )
+ENDPROC(__fiq_abt)
+
+/*
* User mode handlers
*
* EABI note: sp_svc is always 64-bit aligned here, so should S_FRAME_SIZE
@@ -314,7 +365,7 @@ ENDPROC(__pabt_svc)
#error "sizeof(struct pt_regs) must be a multiple of 8"
#endif
- .macro usr_entry
+ .macro usr_entry, trace=1
UNWIND(.fnstart )
UNWIND(.cantunwind ) @ don't unwind the user space
sub sp, sp, #S_FRAME_SIZE
@@ -351,10 +402,12 @@ ENDPROC(__pabt_svc)
@
zero_fp
+ .if \trace
#ifdef CONFIG_IRQSOFF_TRACER
bl trace_hardirqs_off
#endif
ct_user_exit save = 0
+ .endif
.endm
.macro kuser_cmpxchg_check
@@ -683,6 +736,17 @@ ENTRY(ret_from_exception)
ENDPROC(__pabt_usr)
ENDPROC(ret_from_exception)
+ .align 5
+__fiq_usr:
+ usr_entry trace=0
+ kuser_cmpxchg_check
+ mov r0, sp @ struct pt_regs *regs
+ bl handle_fiq_as_nmi
+ get_thread_info tsk
+ restore_user_regs fast = 0, offset = 0
+ UNWIND(.fnend )
+ENDPROC(__fiq_usr)
+
/*
* Register switch for ARMv3 and ARMv4 processors
* r0 = previous task_struct, r1 = previous thread_info, r2 = next thread_info
@@ -1118,17 +1182,29 @@ vector_addrexcptn:
b vector_addrexcptn
/*=============================================================================
- * Undefined FIQs
+ * FIQ "NMI" handler
*-----------------------------------------------------------------------------
- * Enter in FIQ mode, spsr = ANY CPSR, lr = ANY PC
- * MUST PRESERVE SVC SPSR, but need to switch to SVC mode to show our msg.
- * Basically to switch modes, we *HAVE* to clobber one register... brain
- * damage alert! I don't think that we can execute any code in here in any
- * other mode than FIQ... Ok you can switch to another mode, but you can't
- * get out of that mode without clobbering one register.
+ * Handle a FIQ using the SVC stack allowing FIQ act like NMI on x86
+ * systems.
*/
-vector_fiq:
- subs pc, lr, #4
+ vector_stub fiq, FIQ_MODE, 4
+
+ .long __fiq_usr @ 0 (USR_26 / USR_32)
+ .long __fiq_svc @ 1 (FIQ_26 / FIQ_32)
+ .long __fiq_svc @ 2 (IRQ_26 / IRQ_32)
+ .long __fiq_svc @ 3 (SVC_26 / SVC_32)
+ .long __fiq_svc @ 4
+ .long __fiq_svc @ 5
+ .long __fiq_svc @ 6
+ .long __fiq_abt @ 7
+ .long __fiq_svc @ 8
+ .long __fiq_svc @ 9
+ .long __fiq_svc @ a
+ .long __fiq_svc @ b
+ .long __fiq_svc @ c
+ .long __fiq_svc @ d
+ .long __fiq_svc @ e
+ .long __fiq_svc @ f
.globl vector_fiq_offset
.equ vector_fiq_offset, vector_fiq