History log of /arch/frv/kernel/head.S
Revision Date Author Comments
c0b81e003678b983fbe652316a83413d59c8032c 06-May-2013 Geert Uytterhoeven <geert@linux-m68k.org> frv: head.S - Remove commented-out initialization code

The commented-out calls to processor_init() and unit_init() seem to have
been copied from mn10300, when starting the frv port. Remove them.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
b6f4e451de78547a369a8dbb7bcb56c1919a6b79 20-Feb-2010 Denys Vlasenko <vda.linux@googlemail.com> Rename special text sections in arch/frv from .text.XXX to .text..XXX.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
b6a8d95c95814079ded93c14c4b394015d8b65cd 26-Apr-2009 Tim Abbott <tabbott@MIT.EDU> frv: convert frv to use __HEAD and HEAD_TEXT macros.

This has the consequence of changing the section name use for head
code from ".text.head" to ".head.text". Since this commit changes all
users in the architecture, this change should be harmless.

Signed-off-by: Tim Abbott <tabbott@mit.edu>
Cc: David Howells <dhowells@redhat.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
84e8cd6dbc00b4979e8d1c15c80d91987aeb3417 10-Jul-2006 David Howells <dhowells@redhat.com> [PATCH] FRV: Introduce asm-offsets for FRV arch

Introduce the use of asm-offsets into the FRV architecture.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
6ab3d5624e172c553004ecc862bfeac16d9d68b7 30-Jun-2006 Jörn Engel <joern@wohnheim.fh-wedel.de> Remove obsolete #include <linux/config.h>

Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
28baebae73c3ea8b75c7cae225a7db817ab825a9 14-Feb-2006 David Howells <dhowells@redhat.com> [PATCH] FRV: Use virtual interrupt disablement

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>
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 17-Apr-2005 Linus Torvalds <torvalds@ppc970.osdl.org> Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!