xtensa: implement fake NMI
In case perf IRQ is the highest of the medium-level IRQs, and is alone
on its level, it may be treated as NMI:
- LOCKLEVEL is defined to be one level less than EXCM level,
- IRQ masking never lowers current IRQ level,
- new fake exception cause code, EXCCAUSE_MAPPED_NMI is assigned to that
IRQ; new second level exception handler, do_nmi, assigned to it
handles it as NMI,
- atomic operations in configurations without s32c1i still need to mask
all interrupts.
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
diff --git a/arch/xtensa/include/asm/atomic.h b/arch/xtensa/include/asm/atomic.h
index 00b7d46..ebcd1f6 100644
--- a/arch/xtensa/include/asm/atomic.h
+++ b/arch/xtensa/include/asm/atomic.h
@@ -29,7 +29,7 @@
*
* Locking interrupts looks like this:
*
- * rsil a15, LOCKLEVEL
+ * rsil a15, TOPLEVEL
* <code>
* wsr a15, PS
* rsync
@@ -106,7 +106,7 @@
unsigned int vval; \
\
__asm__ __volatile__( \
- " rsil a15, "__stringify(LOCKLEVEL)"\n"\
+ " rsil a15, "__stringify(TOPLEVEL)"\n"\
" l32i %0, %2, 0\n" \
" " #op " %0, %0, %1\n" \
" s32i %0, %2, 0\n" \
@@ -124,7 +124,7 @@
unsigned int vval; \
\
__asm__ __volatile__( \
- " rsil a15,"__stringify(LOCKLEVEL)"\n" \
+ " rsil a15,"__stringify(TOPLEVEL)"\n" \
" l32i %0, %2, 0\n" \
" " #op " %0, %0, %1\n" \
" s32i %0, %2, 0\n" \
@@ -272,7 +272,7 @@
unsigned int vval;
__asm__ __volatile__(
- " rsil a15,"__stringify(LOCKLEVEL)"\n"
+ " rsil a15,"__stringify(TOPLEVEL)"\n"
" l32i %0, %2, 0\n"
" xor %1, %4, %3\n"
" and %0, %0, %4\n"
@@ -306,7 +306,7 @@
unsigned int vval;
__asm__ __volatile__(
- " rsil a15,"__stringify(LOCKLEVEL)"\n"
+ " rsil a15,"__stringify(TOPLEVEL)"\n"
" l32i %0, %2, 0\n"
" or %0, %0, %1\n"
" s32i %0, %2, 0\n"
diff --git a/arch/xtensa/include/asm/cmpxchg.h b/arch/xtensa/include/asm/cmpxchg.h
index 370b26f..201e900 100644
--- a/arch/xtensa/include/asm/cmpxchg.h
+++ b/arch/xtensa/include/asm/cmpxchg.h
@@ -34,7 +34,7 @@
return new;
#else
__asm__ __volatile__(
- " rsil a15, "__stringify(LOCKLEVEL)"\n"
+ " rsil a15, "__stringify(TOPLEVEL)"\n"
" l32i %0, %1, 0\n"
" bne %0, %2, 1f\n"
" s32i %3, %1, 0\n"
@@ -123,7 +123,7 @@
#else
unsigned long tmp;
__asm__ __volatile__(
- " rsil a15, "__stringify(LOCKLEVEL)"\n"
+ " rsil a15, "__stringify(TOPLEVEL)"\n"
" l32i %0, %1, 0\n"
" s32i %2, %1, 0\n"
" wsr a15, ps\n"
diff --git a/arch/xtensa/include/asm/irqflags.h b/arch/xtensa/include/asm/irqflags.h
index ea36674..8e090c7 100644
--- a/arch/xtensa/include/asm/irqflags.h
+++ b/arch/xtensa/include/asm/irqflags.h
@@ -6,6 +6,7 @@
* for more details.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
+ * Copyright (C) 2015 Cadence Design Systems Inc.
*/
#ifndef _XTENSA_IRQFLAGS_H
@@ -23,8 +24,27 @@
static inline unsigned long arch_local_irq_save(void)
{
unsigned long flags;
- asm volatile("rsil %0, "__stringify(LOCKLEVEL)
+#if XTENSA_FAKE_NMI
+#if defined(CONFIG_DEBUG_KERNEL) && (LOCKLEVEL | TOPLEVEL) >= XCHAL_DEBUGLEVEL
+ unsigned long tmp;
+
+ asm volatile("rsr %0, ps\t\n"
+ "extui %1, %0, 0, 4\t\n"
+ "bgei %1, "__stringify(LOCKLEVEL)", 1f\t\n"
+ "rsil %0, "__stringify(LOCKLEVEL)"\n"
+ "1:"
+ : "=a" (flags), "=a" (tmp) :: "memory");
+#else
+ asm volatile("rsr %0, ps\t\n"
+ "or %0, %0, %1\t\n"
+ "xsr %0, ps\t\n"
+ "rsync"
+ : "=&a" (flags) : "a" (LOCKLEVEL) : "memory");
+#endif
+#else
+ asm volatile("rsil %0, "__stringify(LOCKLEVEL)
: "=a" (flags) :: "memory");
+#endif
return flags;
}
diff --git a/arch/xtensa/include/asm/processor.h b/arch/xtensa/include/asm/processor.h
index b61bdf0..83e2e4bc 100644
--- a/arch/xtensa/include/asm/processor.h
+++ b/arch/xtensa/include/asm/processor.h
@@ -1,11 +1,10 @@
/*
- * include/asm-xtensa/processor.h
- *
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2008 Tensilica Inc.
+ * Copyright (C) 2015 Cadence Design Systems Inc.
*/
#ifndef _XTENSA_PROCESSOR_H
@@ -45,6 +44,14 @@
#define STACK_TOP_MAX STACK_TOP
/*
+ * General exception cause assigned to fake NMI. Fake NMI needs to be handled
+ * differently from other interrupts, but it uses common kernel entry/exit
+ * code.
+ */
+
+#define EXCCAUSE_MAPPED_NMI 62
+
+/*
* General exception cause assigned to debug exceptions. Debug exceptions go
* to their own vector, rather than the general exception vectors (user,
* kernel, double); and their specific causes are reported via DEBUGCAUSE
@@ -65,10 +72,30 @@
#define VALID_DOUBLE_EXCEPTION_ADDRESS 64
+#define XTENSA_INT_LEVEL(intno) _XTENSA_INT_LEVEL(intno)
+#define _XTENSA_INT_LEVEL(intno) XCHAL_INT##intno##_LEVEL
+
+#define XTENSA_INTLEVEL_MASK(level) _XTENSA_INTLEVEL_MASK(level)
+#define _XTENSA_INTLEVEL_MASK(level) (XCHAL_INTLEVEL##level##_MASK)
+
+#define IS_POW2(v) (((v) & ((v) - 1)) == 0)
+
+#define PROFILING_INTLEVEL XTENSA_INT_LEVEL(XCHAL_PROFILING_INTERRUPT)
+
/* LOCKLEVEL defines the interrupt level that masks all
* general-purpose interrupts.
*/
+#if defined(CONFIG_XTENSA_VARIANT_HAVE_PERF_EVENTS) && \
+ defined(XCHAL_PROFILING_INTERRUPT) && \
+ PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
+ XCHAL_EXCM_LEVEL > 1 && \
+ IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL))
+#define LOCKLEVEL (XCHAL_EXCM_LEVEL - 1)
+#else
#define LOCKLEVEL XCHAL_EXCM_LEVEL
+#endif
+#define TOPLEVEL XCHAL_EXCM_LEVEL
+#define XTENSA_FAKE_NMI (LOCKLEVEL < TOPLEVEL)
/* WSBITS and WBBITS are the width of the WINDOWSTART and WINDOWBASE
* registers