xtensa: keep a3 and excsave1 on entry to exception handlers
Based on the SMP patch by Joe Taylor and subsequent fixes.
Preserve exception table pointer (normally stored in excsave1 SR) as it
cannot be easily restored in SMP environment.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index 3f3de28..ab025c1 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -91,9 +91,9 @@
* a0: trashed, original value saved on stack (PT_AREG0)
* a1: a1
* a2: new stack pointer, original value in depc
- * a3: dispatch table
+ * a3: a3
* depc: a2, original value saved on stack (PT_DEPC)
- * excsave1: a3
+ * excsave1: dispatch table
*
* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
@@ -109,9 +109,8 @@
ENTRY(user_exception)
- /* Save a2, a3, and depc, restore excsave_1 and set SP. */
+ /* Save a1, a2, a3, and set SP. */
- xsr a3, excsave1
rsr a0, depc
s32i a1, a2, PT_AREG1
s32i a0, a2, PT_AREG2
@@ -237,9 +236,9 @@
* a0: trashed, original value saved on stack (PT_AREG0)
* a1: a1
* a2: new stack pointer, original in DEPC
- * a3: dispatch table
+ * a3: a3
* depc: a2, original value saved on stack (PT_DEPC)
- * excsave_1: a3
+ * excsave_1: dispatch table
*
* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
@@ -255,9 +254,8 @@
ENTRY(kernel_exception)
- /* Save a0, a2, a3, DEPC and set SP. */
+ /* Save a1, a2, a3, and set SP. */
- xsr a3, excsave1 # restore a3, excsave_1
rsr a0, depc # get a2
s32i a1, a2, PT_AREG1
s32i a0, a2, PT_AREG2
@@ -408,7 +406,7 @@
* exception handler and call the exception handler.
*/
- movi a4, exc_table
+ rsr a4, excsave1
mov a6, a1 # pass stack frame
mov a7, a0 # pass EXCCAUSE
addx4 a4, a0, a4
@@ -832,9 +830,9 @@
* a0: trashed, original value saved on stack (PT_AREG0)
* a1: a1
* a2: new stack pointer, original in DEPC
- * a3: dispatch table
+ * a3: a3
* depc: a2, original value saved on stack (PT_DEPC)
- * excsave_1: a3
+ * excsave_1: dispatch table
*
* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
@@ -857,18 +855,16 @@
rsr a0, depc # get a2
s32i a4, a2, PT_AREG4 # save a4 and
+ s32i a3, a2, PT_AREG3
s32i a0, a2, PT_AREG2 # a2 to stack
/* Exit critical section. */
movi a0, 0
+ rsr a3, excsave1
s32i a0, a3, EXC_TABLE_FIXUP
- /* Restore a3, excsave_1 */
-
- xsr a3, excsave1 # make sure excsave_1 is valid for dbl.
rsr a4, epc1 # get exception address
- s32i a3, a2, PT_AREG3 # save a3 to stack
#ifdef ALLOCA_EXCEPTION_IN_IRAM
#error iram not supported
@@ -1007,9 +1003,9 @@
* a0: trashed, original value saved on stack (PT_AREG0)
* a1: a1
* a2: new stack pointer, original in DEPC
- * a3: dispatch table
+ * a3: a3
* depc: a2, original value saved on stack (PT_DEPC)
- * excsave_1: a3
+ * excsave_1: dispatch table
*/
ENTRY(fast_syscall_kernel)
@@ -1056,7 +1052,6 @@
l32i a0, a2, PT_AREG0 # restore a0
xsr a2, depc # restore a2, depc
- rsr a3, excsave1
wsr a0, excsave1
movi a0, unrecoverable_exception
@@ -1078,10 +1073,10 @@
* a0: a2 (syscall-nr), original value saved on stack (PT_AREG0)
* a1: a1
* a2: new stack pointer, original in a0 and DEPC
- * a3: dispatch table, original in excsave_1
+ * a3: a3
* a4..a15: unchanged
* depc: a2, original value saved on stack (PT_DEPC)
- * excsave_1: a3
+ * excsave_1: dispatch table
*
* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
@@ -1114,8 +1109,6 @@
ENTRY(fast_syscall_xtensa)
- xsr a3, excsave1 # restore a3, excsave1
-
s32i a7, a2, PT_AREG7 # we need an additional register
movi a7, 4 # sizeof(unsigned int)
access_ok a3, a7, a0, a2, .Leac # a0: scratch reg, a2: sp
@@ -1178,9 +1171,9 @@
* a0: trashed, original value saved on stack (PT_AREG0)
* a1: a1
* a2: new stack pointer, original in DEPC
- * a3: dispatch table
+ * a3: a3
* depc: a2, original value saved on stack (PT_DEPC)
- * excsave_1: a3
+ * excsave_1: dispatch table
*
* Note: We assume the stack pointer is EXC_TABLE_KSTK in the fixup handler.
*/
@@ -1189,15 +1182,16 @@
/* Register a FIXUP handler (pass current wb as a parameter) */
+ xsr a3, excsave1
movi a0, fast_syscall_spill_registers_fixup
s32i a0, a3, EXC_TABLE_FIXUP
rsr a0, windowbase
s32i a0, a3, EXC_TABLE_PARAM
+ xsr a3, excsave1 # restore a3 and excsave_1
- /* Save a3 and SAR on stack. */
+ /* Save a3, a4 and SAR on stack. */
rsr a0, sar
- xsr a3, excsave1 # restore a3 and excsave_1
s32i a3, a2, PT_AREG3
s32i a4, a2, PT_AREG4
s32i a0, a2, PT_AREG5 # store SAR to PT_AREG5
@@ -1251,14 +1245,14 @@
* in WS, so that the exception handlers save them to the task stack.
*/
- rsr a3, excsave1 # get spill-mask
+ xsr a3, excsave1 # get spill-mask
slli a2, a3, 1 # shift left by one
slli a3, a2, 32-WSBITS
src a2, a2, a3 # a1 = xxwww1yyxxxwww1yy......
wsr a2, windowstart # set corrected windowstart
- movi a3, exc_table
+ rsr a3, excsave1
l32i a2, a3, EXC_TABLE_DOUBLE_SAVE # restore a2
l32i a3, a3, EXC_TABLE_PARAM # original WB (in user task)
@@ -1295,7 +1289,7 @@
/* Jump to the exception handler. */
- movi a3, exc_table
+ rsr a3, excsave1
rsr a0, exccause
addx4 a0, a0, a3 # find entry in table
l32i a0, a0, EXC_TABLE_FAST_USER # load handler
@@ -1312,6 +1306,7 @@
xsr a3, excsave1
movi a2, fast_syscall_spill_registers_fixup
s32i a2, a3, EXC_TABLE_FIXUP
+ s32i a0, a3, EXC_TABLE_DOUBLE_SAVE
rsr a2, windowbase
s32i a2, a3, EXC_TABLE_PARAM
l32i a2, a3, EXC_TABLE_KSTK
@@ -1323,11 +1318,6 @@
wsr a3, windowbase
rsync
- /* Restore a3 and return. */
-
- movi a3, exc_table
- xsr a3, excsave1
-
rfde
@@ -1514,9 +1504,8 @@
movi a0, 0
- movi a3, exc_table
+ rsr a3, excsave1
l32i a1, a3, EXC_TABLE_KSTK
- wsr a3, excsave1
movi a4, (1 << PS_WOE_BIT) | LOCKLEVEL
wsr a4, ps
@@ -1560,9 +1549,9 @@
* a0: trashed, original value saved on stack (PT_AREG0)
* a1: a1
* a2: new stack pointer, original in DEPC
- * a3: dispatch table
+ * a3: a3
* depc: a2, original value saved on stack (PT_DEPC)
- * excsave_1: a3
+ * excsave_1: dispatch table
*
* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
@@ -1570,9 +1559,10 @@
ENTRY(fast_second_level_miss)
- /* Save a1. Note: we don't expect a double exception. */
+ /* Save a1 and a3. Note: we don't expect a double exception. */
s32i a1, a2, PT_AREG1
+ s32i a3, a2, PT_AREG3
/* We need to map the page of PTEs for the user task. Find
* the pointer to that page. Also, it's possible for tsk->mm
@@ -1594,9 +1584,6 @@
l32i a0, a1, TASK_MM # tsk->mm
beqz a0, 9f
-
- /* We deliberately destroy a3 that holds the exception table. */
-
8: rsr a3, excvaddr # fault address
_PGD_OFFSET(a0, a3, a1)
l32i a0, a0, 0 # read pmdval
@@ -1647,7 +1634,7 @@
/* Exit critical section. */
-4: movi a3, exc_table # restore a3
+4: rsr a3, excsave1
movi a0, 0
s32i a0, a3, EXC_TABLE_FIXUP
@@ -1655,8 +1642,8 @@
l32i a0, a2, PT_AREG0
l32i a1, a2, PT_AREG1
+ l32i a3, a2, PT_AREG3
l32i a2, a2, PT_DEPC
- xsr a3, excsave1
bgeui a2, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f
@@ -1743,11 +1730,8 @@
2: /* Invalid PGD, default exception handling */
- movi a3, exc_table
rsr a1, depc
- xsr a3, excsave1
s32i a1, a2, PT_AREG2
- s32i a3, a2, PT_AREG3
mov a1, a2
rsr a2, ps
@@ -1767,9 +1751,9 @@
* a0: trashed, original value saved on stack (PT_AREG0)
* a1: a1
* a2: new stack pointer, original in DEPC
- * a3: dispatch table
+ * a3: a3
* depc: a2, original value saved on stack (PT_DEPC)
- * excsave_1: a3
+ * excsave_1: dispatch table
*
* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
@@ -1777,17 +1761,17 @@
ENTRY(fast_store_prohibited)
- /* Save a1 and a4. */
+ /* Save a1 and a3. */
s32i a1, a2, PT_AREG1
- s32i a4, a2, PT_AREG4
+ s32i a3, a2, PT_AREG3
GET_CURRENT(a1,a2)
l32i a0, a1, TASK_MM # tsk->mm
beqz a0, 9f
8: rsr a1, excvaddr # fault address
- _PGD_OFFSET(a0, a1, a4)
+ _PGD_OFFSET(a0, a1, a3)
l32i a0, a0, 0
beqz a0, 2f
@@ -1796,39 +1780,37 @@
* and is not PAGE_NONE. See pgtable.h for possible PTE layouts.
*/
- _PTE_OFFSET(a0, a1, a4)
- l32i a4, a0, 0 # read pteval
+ _PTE_OFFSET(a0, a1, a3)
+ l32i a3, a0, 0 # read pteval
movi a1, _PAGE_CA_INVALID
- ball a4, a1, 2f
- bbci.l a4, _PAGE_WRITABLE_BIT, 2f
+ ball a3, a1, 2f
+ bbci.l a3, _PAGE_WRITABLE_BIT, 2f
movi a1, _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_HW_WRITE
- or a4, a4, a1
+ or a3, a3, a1
rsr a1, excvaddr
- s32i a4, a0, 0
+ s32i a3, a0, 0
/* We need to flush the cache if we have page coloring. */
#if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK
dhwb a0, 0
#endif
pdtlb a0, a1
- wdtlb a4, a0
+ wdtlb a3, a0
/* Exit critical section. */
movi a0, 0
+ rsr a3, excsave1
s32i a0, a3, EXC_TABLE_FIXUP
/* Restore the working registers, and return. */
- l32i a4, a2, PT_AREG4
+ l32i a3, a2, PT_AREG3
l32i a1, a2, PT_AREG1
l32i a0, a2, PT_AREG0
l32i a2, a2, PT_DEPC
- /* Restore excsave1 and a3. */
-
- xsr a3, excsave1
bgeui a2, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f
rsr a2, depc
@@ -1845,11 +1827,8 @@
2: /* If there was a problem, handle fault in C */
- rsr a4, depc # still holds a2
- xsr a3, excsave1
- s32i a4, a2, PT_AREG2
- s32i a3, a2, PT_AREG3
- l32i a4, a2, PT_AREG4
+ rsr a3, depc # still holds a2
+ s32i a3, a2, PT_AREG2
mov a1, a2
rsr a2, ps