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sh: GUSA atomic rollback support.

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This implements kernel-level atomic rollback built on top of gUSA,
as an alternative non-IRQ based atomicity method. This is generally
a faster method for platforms that are lacking the LL/SC pairs that
SH-4A and later use, and is only supportable on legacy cores.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Stuart Menefy
2007-11-30 16:12:36 +09:00
committed by Paul Mundt
parent 53ff09422e
commit 1efe4ce3ca
13 changed files with 590 additions and 180 deletions
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19
arch/sh/kernel/entry-common.S
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@@ -176,25 +176,6 @@ work_notifysig:
jmp @r1
lds r0, pr
work_resched:
#if defined(CONFIG_GUSA) && !defined(CONFIG_PREEMPT)
! gUSA handling
mov.l @(OFF_SP,r15), r0 ! get user space stack pointer
mov r0, r1
shll r0
bf/s 1f
shll r0
bf/s 1f
mov #OFF_PC, r0
! SP >= 0xc0000000 : gUSA mark
mov.l @(r0,r15), r2 ! get user space PC (program counter)
mov.l @(OFF_R0,r15), r3 ! end point
cmp/hs r3, r2 ! r2 >= r3?
bt 1f
add r3, r1 ! rewind point #2
mov.l r1, @(r0,r15) ! reset PC to rewind point #2
!
1:
#endif
mov.l 1f, r1
jsr @r1 ! schedule
nop