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-rw-r--r--arch/arm/kernel/entry-armv.S98
-rw-r--r--arch/arm/kernel/entry-header.S47
-rw-r--r--arch/arm/kernel/fiq.c17
-rw-r--r--arch/arm/kernel/setup.c8
-rw-r--r--arch/arm/kernel/traps.c26
5 files changed, 180 insertions, 16 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
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 2fdf8679b46e..0d91ca05d55b 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -216,6 +216,34 @@
ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr
.endm
+ @
+ @ svc_exit_via_fiq - like svc_exit but switches to FIQ mode before exit
+ @
+ @ This macro acts in a similar manner to svc_exit but switches to FIQ
+ @ mode to restore the final part of the register state.
+ @
+ @ We cannot use the normal svc_exit procedure because that would
+ @ clobber spsr_svc (FIQ could be delivered during the first few
+ @ instructions of vector_swi meaning its contents have not been
+ @ saved anywhere).
+ @
+ @ Note that, unlike svc_exit, this macro also does not allow a caller
+ @ supplied rpsr. This is because the FIQ exceptions are not re-entrant
+ @ and the handlers cannot call into the scheduler (meaning the value
+ @ on the stack remains correct).
+ @
+ .macro svc_exit_via_fiq
+ mov r0, sp
+ ldmib r0, {r1 - r14} @ abort is deadly from here onward (it will
+ @ clobber state restored below)
+ msr cpsr_c, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT
+ add r8, r0, #S_PC
+ ldr r9, [r0, #S_PSR]
+ msr spsr_cxsf, r9
+ ldr r0, [r0, #S_R0]
+ ldmia r8, {pc}^
+ .endm
+
.macro restore_user_regs, fast = 0, offset = 0
ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr
ldr lr, [sp, #\offset + S_PC]! @ get pc
@@ -267,6 +295,25 @@
rfeia sp!
.endm
+ @
+ @ svc_exit_via_fiq - like svc_exit but switches to FIQ mode before exit
+ @
+ @ For full details see non-Thumb implementation above.
+ @
+ .macro svc_exit_via_fiq
+ add r0, sp, #S_R2
+ ldr lr, [sp, #S_LR]
+ ldr sp, [sp, #S_SP] @ abort is deadly from here onward (it will
+ @ clobber state restored below)
+ ldmia r0, {r2 - r12}
+ mov r1, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT
+ msr cpsr_c, r1
+ sub r0, #S_R2
+ add r8, r0, #S_PC
+ ldmia r0, {r0 - r1}
+ rfeia r8
+ .endm
+
#ifdef CONFIG_CPU_V7M
/*
* Note we don't need to do clrex here as clearing the local monitor is
diff --git a/arch/arm/kernel/fiq.c b/arch/arm/kernel/fiq.c
index 918875d96d5d..b37752a96652 100644
--- a/arch/arm/kernel/fiq.c
+++ b/arch/arm/kernel/fiq.c
@@ -52,7 +52,8 @@
(unsigned)&vector_fiq_offset; \
})
-static unsigned long no_fiq_insn;
+static unsigned long dfl_fiq_insn;
+static struct pt_regs dfl_fiq_regs;
/* Default reacquire function
* - we always relinquish FIQ control
@@ -60,8 +61,15 @@ static unsigned long no_fiq_insn;
*/
static int fiq_def_op(void *ref, int relinquish)
{
- if (!relinquish)
- set_fiq_handler(&no_fiq_insn, sizeof(no_fiq_insn));
+ if (!relinquish) {
+ /* Restore default handler and registers */
+ local_fiq_disable();
+ set_fiq_regs(&dfl_fiq_regs);
+ set_fiq_handler(&dfl_fiq_insn, sizeof(dfl_fiq_insn));
+ local_fiq_enable();
+
+ /* FIXME: notify irq controller to standard enable FIQs */
+ }
return 0;
}
@@ -150,6 +158,7 @@ EXPORT_SYMBOL(disable_fiq);
void __init init_FIQ(int start)
{
unsigned offset = FIQ_OFFSET;
- no_fiq_insn = *(unsigned long *)(0xffff0000 + offset);
+ dfl_fiq_insn = *(unsigned long *)(0xffff0000 + offset);
+ get_fiq_regs(&dfl_fiq_regs);
fiq_start = start;
}
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 84db893dedc2..c03106378b49 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -133,6 +133,7 @@ struct stack {
u32 irq[3];
u32 abt[3];
u32 und[3];
+ u32 fiq[3];
} ____cacheline_aligned;
#ifndef CONFIG_CPU_V7M
@@ -470,7 +471,10 @@ void notrace cpu_init(void)
"msr cpsr_c, %5\n\t"
"add r14, %0, %6\n\t"
"mov sp, r14\n\t"
- "msr cpsr_c, %7"
+ "msr cpsr_c, %7\n\t"
+ "add r14, %0, %8\n\t"
+ "mov sp, r14\n\t"
+ "msr cpsr_c, %9"
:
: "r" (stk),
PLC (PSR_F_BIT | PSR_I_BIT | IRQ_MODE),
@@ -479,6 +483,8 @@ void notrace cpu_init(void)
"I" (offsetof(struct stack, abt[0])),
PLC (PSR_F_BIT | PSR_I_BIT | UND_MODE),
"I" (offsetof(struct stack, und[0])),
+ PLC (PSR_F_BIT | PSR_I_BIT | FIQ_MODE),
+ "I" (offsetof(struct stack, fiq[0])),
PLC (PSR_F_BIT | PSR_I_BIT | SVC_MODE)
: "r14");
#endif
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index c8e4bb714944..58348631671d 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -25,6 +25,7 @@
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/sched.h>
+#include <linux/irq.h>
#include <linux/atomic.h>
#include <asm/cacheflush.h>
@@ -467,6 +468,31 @@ asmlinkage void do_unexp_fiq (struct pt_regs *regs)
}
/*
+ * Handle FIQ similarly to NMI on x86 systems.
+ *
+ * The runtime environment for NMIs is extremely restrictive
+ * (NMIs can pre-empt critical sections meaning almost all locking is
+ * forbidden) meaning this default FIQ handling must only be used in
+ * circumstances where non-maskability improves robustness, such as
+ * watchdog or debug logic.
+ *
+ * This handler is not appropriate for general purpose use in drivers
+ * platform code and can be overrideen using set_fiq_handler.
+ */
+asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
+{
+ struct pt_regs *old_regs = set_irq_regs(regs);
+
+ nmi_enter();
+
+ /* nop. FIQ handlers for special arch/arm features can be added here. */
+
+ nmi_exit();
+
+ set_irq_regs(old_regs);
+}
+
+/*
* bad_mode handles the impossible case in the vectors. If you see one of
* these, then it's extremely serious, and could mean you have buggy hardware.
* It never returns, and never tries to sync. We hope that we can at least