28baebae73
Make the FRV arch use virtual interrupt disablement because accesses to the processor status register (PSR) are relatively slow and because we will soon have the need to deal with multiple interrupt controls at the same time (separate h/w and inter-core interrupts). The way this is done is to dedicate one of the four integer condition code registers (ICC2) to maintaining a virtual interrupt disablement state whilst inside the kernel. This uses the ICC2.Z flag (Zero) to indicate whether the interrupts are virtually disabled and the ICC2.C flag (Carry) to indicate whether the interrupts are physically disabled. ICC2.Z is set to indicate interrupts are virtually disabled. ICC2.C is set to indicate interrupts are physically enabled. Under normal running conditions Z==0 and C==1. Disabling interrupts with local_irq_disable() doesn't then actually physically disable interrupts - it merely sets ICC2.Z to 1. Should an interrupt then happen, the exception prologue will note ICC2.Z is set and branch out of line using one instruction (an unlikely BEQ). Here it will physically disable interrupts and clear ICC2.C. When it comes time to enable interrupts (local_irq_enable()), this simply clears the ICC2.Z flag and invokes a trap #2 if both Z and C flags are clear (the HI integer condition). This can be done with the TIHI conditional trap instruction. The trap then physically reenables interrupts and sets ICC2.C again. Upon returning the interrupt will be taken as interrupts will then be enabled. Note that whilst processing the trap, the whole exceptions system is disabled, and so an interrupt can't happen till it returns. If no pending interrupt had happened, ICC2.C would still be set, the HI condition would not be fulfilled, and no trap will happen. Saving interrupts (local_irq_save) is simply a matter of pulling the ICC2.Z flag out of the CCR register, shifting it down and masking it off. This gives a result of 0 if interrupts were enabled and 1 if they weren't. Restoring interrupts (local_irq_restore) is then a matter of taking the saved value mentioned previously and XOR'ing it against 1. If it was one, the result will be zero, and if it was zero the result will be non-zero. This result is then used to affect the ICC2.Z flag directly (it is a condition code flag after all). An XOR instruction does not affect the Carry flag, and so that bit of state is unchanged. The two flags can then be sampled to see if they're both zero using the trap (TIHI) as for the unconditional reenablement (local_irq_enable). This patch also: (1) Modifies the debugging stub (break.S) to handle single-stepping crossing into the trap #2 handler and into virtually disabled interrupts. (2) Removes superseded fixup pointers from the second instructions in the trap tables (there's no a separate fixup table for this). (3) Declares the trap #3 vector for use in .org directives in the trap table. (4) Moves irq_enter() and irq_exit() in do_IRQ() to avoid problems with virtual interrupt handling, and removes the duplicate code that has now been folded into irq_exit() (softirq and preemption handling). (5) Tells the compiler in the arch Makefile that ICC2 is now reserved. (6) Documents the in-kernel ABI, including the virtual interrupts. (7) Renames the old irq management functions to different names. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
119 lines
2.9 KiB
Makefile
119 lines
2.9 KiB
Makefile
#
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# frv/Makefile
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#
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# This file is included by the global makefile so that you can add your own
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# architecture-specific flags and dependencies. Remember to do have actions
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# for "archclean" and "archdep" for cleaning up and making dependencies for
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# this architecture
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#
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# This file is subject to the terms and conditions of the GNU General Public
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# License. See the file "COPYING" in the main directory of this archive
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# for more details.
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#
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# Copyright (c) 2003, 2004 Red Hat Inc.
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# - Written by David Howells <dhowells@redhat.com>
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# - Derived from arch/m68knommu/Makefile,
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# Copyright (c) 1999,2001 D. Jeff Dionne <jeff@lineo.ca>,
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# Rt-Control Inc. / Lineo, Inc.
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#
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# Copyright (C) 1998,1999 D. Jeff Dionne <jeff@uclinux.org>,
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# Kenneth Albanowski <kjahds@kjahds.com>,
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#
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# Based on arch/m68k/Makefile:
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# Copyright (C) 1994 by Hamish Macdonald
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#
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CCSPECS := $(shell $(CC) -v 2>&1 | grep "^Reading specs from " | head -1 | cut -c20-)
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CCDIR := $(strip $(patsubst %/specs,%,$(CCSPECS)))
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CPUCLASS := fr400
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# test for cross compiling
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COMPILE_ARCH = $(shell uname -m)
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ifdef CONFIG_MMU
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UTS_SYSNAME = -DUTS_SYSNAME=\"Linux\"
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else
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UTS_SYSNAME = -DUTS_SYSNAME=\"uClinux\"
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endif
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ARCHMODFLAGS += -G0 -mlong-calls
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ifdef CONFIG_GPREL_DATA_8
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CFLAGS += -G8
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else
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ifdef CONFIG_GPREL_DATA_4
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CFLAGS += -G4
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else
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ifdef CONFIG_GPREL_DATA_NONE
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CFLAGS += -G0
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endif
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endif
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endif
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#LDFLAGS_vmlinux := -Map linkmap.txt
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ifdef CONFIG_GC_SECTIONS
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CFLAGS += -ffunction-sections -fdata-sections
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LINKFLAGS += --gc-sections
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endif
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ifndef CONFIG_FRAME_POINTER
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CFLAGS += -mno-linked-fp
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endif
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ifdef CONFIG_CPU_FR451_COMPILE
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CFLAGS += -mcpu=fr450
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AFLAGS += -mcpu=fr450
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ASFLAGS += -mcpu=fr450
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else
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ifdef CONFIG_CPU_FR551_COMPILE
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CFLAGS += -mcpu=fr550
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AFLAGS += -mcpu=fr550
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ASFLAGS += -mcpu=fr550
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else
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CFLAGS += -mcpu=fr400
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AFLAGS += -mcpu=fr400
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ASFLAGS += -mcpu=fr400
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endif
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endif
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# pretend the kernel is going to run on an FR400 with no media-fp unit
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# - reserve CC3 for use with atomic ops
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# - all the extra registers are dealt with only at context switch time
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CFLAGS += -mno-fdpic -mgpr-32 -msoft-float -mno-media
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CFLAGS += -ffixed-fcc3 -ffixed-cc3 -ffixed-gr15 -ffixed-icc2
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AFLAGS += -mno-fdpic
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ASFLAGS += -mno-fdpic
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# make sure the .S files get compiled with debug info
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# and disable optimisations that are unhelpful whilst debugging
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ifdef CONFIG_DEBUG_INFO
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CFLAGS += -O1
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AFLAGS += -Wa,--gdwarf2
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ASFLAGS += -Wa,--gdwarf2
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endif
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head-y := arch/frv/kernel/head.o arch/frv/kernel/init_task.o
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core-y += arch/frv/kernel/ arch/frv/mm/
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libs-y += arch/frv/lib/
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core-$(CONFIG_MB93090_MB00) += arch/frv/mb93090-mb00/
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all: Image
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Image: vmlinux
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$(Q)$(MAKE) $(build)=arch/frv/boot $@
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bootstrap:
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$(Q)$(MAKEBOOT) bootstrap
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archmrproper:
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$(Q)$(MAKE) $(build)=arch/frv/boot mrproper
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archclean:
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$(Q)$(MAKE) $(build)=arch/frv/boot clean
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archdep: scripts/mkdep symlinks
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$(Q)$(MAKE) $(build)=arch/frv/boot dep
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