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authorStuart Menefy <stuart.menefy@st.com>2007-11-30 16:12:36 +0900
committerPaul Mundt <lethal@linux-sh.org>2008-01-28 13:18:58 +0900
commit1efe4ce3ca126da77e450d5a83f7201949d76f62 (patch)
treefbae9902aa4103a9e86d06f841d580f24682e7b3 /arch/sh/kernel/cpu
parent53ff09422e5e7a6d6198b767c8f494e43ec8e3ae (diff)
sh: GUSA atomic rollback support.
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>
Diffstat (limited to 'arch/sh/kernel/cpu')
-rw-r--r--arch/sh/kernel/cpu/sh3/entry.S24
1 files changed, 23 insertions, 1 deletions
diff --git a/arch/sh/kernel/cpu/sh3/entry.S b/arch/sh/kernel/cpu/sh3/entry.S
index 0d12a124055..4004073f98c 100644
--- a/arch/sh/kernel/cpu/sh3/entry.S
+++ b/arch/sh/kernel/cpu/sh3/entry.S
@@ -13,8 +13,9 @@
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
-#include <asm/cpu/mmu_context.h>
#include <asm/unistd.h>
+#include <asm/cpu/mmu_context.h>
+#include <asm/page.h>
! NOTE:
! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address
@@ -409,6 +410,27 @@ ENTRY(handle_exception)
! Using k0, k1 for scratch registers (r0_bank1, r1_bank),
! save all registers onto stack.
!
+
+#ifdef CONFIG_GUSA
+ ! Check for roll back gRB (User and Kernel)
+ mov r15, k0
+ shll k0
+ bf/s 1f
+ shll k0
+ bf/s 1f
+ stc spc, k1
+ stc r0_bank, k0
+ cmp/hs k0, k1 ! test k1 (saved PC) >= k0 (saved r0)
+ bt/s 2f
+ stc r1_bank, k1
+
+ add #-2, k0
+ add r15, k0
+ ldc k0, spc ! PC = saved r0 + r15 - 2
+2: mov k1, r15 ! SP = r1
+1:
+#endif
+
stc ssr, k0 ! Is it from kernel space?
shll k0 ! Check MD bit (bit30) by shifting it into...
shll k0 ! ...the T bit