forked from Minki/linux
xtensa: fix fast_syscall_spill_registers_fixup
fast_syscall_spill_registers_fixup was not correctly updated by the 'keep a3 and excsave1 on entry to exception handlers' patch: it doesn't preserve a3 that it gets on entry, breaking _spill_registers in case of page fault on stack during register spilling, leading to unhandled exception in kernel mode. Preserve a3 by saving it in the original _spill_registers stack frame's a3 during exception handling and restoring it afterwards. Also fix comments and function bounds annotations. Reported-by: Baruch Siach <baruch@tkos.co.il> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Tested-by: Baruch Siach <baruch@tkos.co.il> Signed-off-by: Chris Zankel <chris@zankel.net>
This commit is contained in:
parent
61e6cfa80d
commit
244066f4be
@ -1122,7 +1122,7 @@ ENDPROC(fast_syscall_spill_registers)
|
||||
* a3: exctable, original value in excsave1
|
||||
*/
|
||||
|
||||
fast_syscall_spill_registers_fixup:
|
||||
ENTRY(fast_syscall_spill_registers_fixup)
|
||||
|
||||
rsr a2, windowbase # get current windowbase (a2 is saved)
|
||||
xsr a0, depc # restore depc and a0
|
||||
@ -1134,22 +1134,26 @@ fast_syscall_spill_registers_fixup:
|
||||
*/
|
||||
|
||||
xsr a3, excsave1 # get spill-mask
|
||||
slli a2, a3, 1 # shift left by one
|
||||
slli a3, a3, 1 # shift left by one
|
||||
|
||||
slli a3, a2, 32-WSBITS
|
||||
src a2, a2, a3 # a1 = xxwww1yyxxxwww1yy......
|
||||
slli a2, a3, 32-WSBITS
|
||||
src a2, a3, a2 # a2 = xxwww1yyxxxwww1yy......
|
||||
wsr a2, windowstart # set corrected windowstart
|
||||
|
||||
rsr a3, excsave1
|
||||
l32i a2, a3, EXC_TABLE_DOUBLE_SAVE # restore a2
|
||||
l32i a3, a3, EXC_TABLE_PARAM # original WB (in user task)
|
||||
srli a3, a3, 1
|
||||
rsr a2, excsave1
|
||||
l32i a2, a2, EXC_TABLE_DOUBLE_SAVE # restore a2
|
||||
xsr a2, excsave1
|
||||
s32i a3, a2, EXC_TABLE_DOUBLE_SAVE # save a3
|
||||
l32i a3, a2, EXC_TABLE_PARAM # original WB (in user task)
|
||||
xsr a2, excsave1
|
||||
|
||||
/* Return to the original (user task) WINDOWBASE.
|
||||
* We leave the following frame behind:
|
||||
* a0, a1, a2 same
|
||||
* a3: trashed (saved in excsave_1)
|
||||
* a3: trashed (saved in EXC_TABLE_DOUBLE_SAVE)
|
||||
* depc: depc (we have to return to that address)
|
||||
* excsave_1: a3
|
||||
* excsave_1: exctable
|
||||
*/
|
||||
|
||||
wsr a3, windowbase
|
||||
@ -1159,9 +1163,9 @@ fast_syscall_spill_registers_fixup:
|
||||
* a0: return address
|
||||
* a1: used, stack pointer
|
||||
* a2: kernel stack pointer
|
||||
* a3: available, saved in EXCSAVE_1
|
||||
* a3: available
|
||||
* depc: exception address
|
||||
* excsave: a3
|
||||
* excsave: exctable
|
||||
* Note: This frame might be the same as above.
|
||||
*/
|
||||
|
||||
@ -1181,9 +1185,12 @@ fast_syscall_spill_registers_fixup:
|
||||
rsr a0, exccause
|
||||
addx4 a0, a0, a3 # find entry in table
|
||||
l32i a0, a0, EXC_TABLE_FAST_USER # load handler
|
||||
l32i a3, a3, EXC_TABLE_DOUBLE_SAVE
|
||||
jx a0
|
||||
|
||||
fast_syscall_spill_registers_fixup_return:
|
||||
ENDPROC(fast_syscall_spill_registers_fixup)
|
||||
|
||||
ENTRY(fast_syscall_spill_registers_fixup_return)
|
||||
|
||||
/* When we return here, all registers have been restored (a2: DEPC) */
|
||||
|
||||
@ -1191,13 +1198,13 @@ fast_syscall_spill_registers_fixup_return:
|
||||
|
||||
/* Restore fixup handler. */
|
||||
|
||||
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
|
||||
rsr a2, excsave1
|
||||
s32i a3, a2, EXC_TABLE_DOUBLE_SAVE
|
||||
movi a3, fast_syscall_spill_registers_fixup
|
||||
s32i a3, a2, EXC_TABLE_FIXUP
|
||||
rsr a3, windowbase
|
||||
s32i a3, a2, EXC_TABLE_PARAM
|
||||
l32i a2, a2, EXC_TABLE_KSTK
|
||||
|
||||
/* Load WB at the time the exception occurred. */
|
||||
|
||||
@ -1206,8 +1213,12 @@ fast_syscall_spill_registers_fixup_return:
|
||||
wsr a3, windowbase
|
||||
rsync
|
||||
|
||||
rsr a3, excsave1
|
||||
l32i a3, a3, EXC_TABLE_DOUBLE_SAVE
|
||||
|
||||
rfde
|
||||
|
||||
ENDPROC(fast_syscall_spill_registers_fixup_return)
|
||||
|
||||
/*
|
||||
* spill all registers.
|
||||
|
Loading…
Reference in New Issue
Block a user