diff options
Diffstat (limited to 'arch/xtensa/kernel/entry.S')
| -rw-r--r-- | arch/xtensa/kernel/entry.S | 438 |
1 files changed, 231 insertions, 207 deletions
diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S index de1dfa18d0a..ef7f4990722 100644 --- a/arch/xtensa/kernel/entry.S +++ b/arch/xtensa/kernel/entry.S @@ -1081,185 +1081,53 @@ ENTRY(fast_syscall_spill_registers) rsr a0, sar s32i a3, a2, PT_AREG3 - s32i a4, a2, PT_AREG4 - s32i a0, a2, PT_AREG5 # store SAR to PT_AREG5 + s32i a0, a2, PT_SAR - /* The spill routine might clobber a7, a11, and a15. */ + /* The spill routine might clobber a4, a7, a8, a11, a12, and a15. */ + s32i a4, a2, PT_AREG4 s32i a7, a2, PT_AREG7 + s32i a8, a2, PT_AREG8 s32i a11, a2, PT_AREG11 + s32i a12, a2, PT_AREG12 s32i a15, a2, PT_AREG15 - call0 _spill_registers # destroys a3, a4, and SAR - - /* Advance PC, restore registers and SAR, and return from exception. */ - - l32i a3, a2, PT_AREG5 - l32i a4, a2, PT_AREG4 - l32i a0, a2, PT_AREG0 - wsr a3, sar - l32i a3, a2, PT_AREG3 - - /* Restore clobbered registers. */ - - l32i a7, a2, PT_AREG7 - l32i a11, a2, PT_AREG11 - l32i a15, a2, PT_AREG15 - - movi a2, 0 - rfe - -ENDPROC(fast_syscall_spill_registers) - -/* Fixup handler. - * - * We get here if the spill routine causes an exception, e.g. tlb miss. - * We basically restore WINDOWBASE and WINDOWSTART to the condition when - * we entered the spill routine and jump to the user exception handler. - * - * a0: value of depc, original value in depc - * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE - * a3: exctable, original value in excsave1 - */ - -fast_syscall_spill_registers_fixup: - - rsr a2, windowbase # get current windowbase (a2 is saved) - xsr a0, depc # restore depc and a0 - ssl a2 # set shift (32 - WB) - - /* We need to make sure the current registers (a0-a3) are preserved. - * To do this, we simply set the bit for the current window frame - * in WS, so that the exception handlers save them to the task stack. - */ - - 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 - - rsr a3, excsave1 - l32i a2, a3, EXC_TABLE_DOUBLE_SAVE # restore a2 - l32i a3, a3, EXC_TABLE_PARAM # original WB (in user task) - - /* Return to the original (user task) WINDOWBASE. - * We leave the following frame behind: - * a0, a1, a2 same - * a3: trashed (saved in excsave_1) - * depc: depc (we have to return to that address) - * excsave_1: a3 - */ - - wsr a3, windowbase - rsync - - /* We are now in the original frame when we entered _spill_registers: - * a0: return address - * a1: used, stack pointer - * a2: kernel stack pointer - * a3: available, saved in EXCSAVE_1 - * depc: exception address - * excsave: a3 - * Note: This frame might be the same as above. - */ - - /* Setup stack pointer. */ - - addi a2, a2, -PT_USER_SIZE - s32i a0, a2, PT_AREG0 - - /* Make sure we return to this fixup handler. */ - - movi a3, fast_syscall_spill_registers_fixup_return - s32i a3, a2, PT_DEPC # setup depc - - /* Jump to the exception handler. */ - - rsr a3, excsave1 - rsr a0, exccause - addx4 a0, a0, a3 # find entry in table - l32i a0, a0, EXC_TABLE_FAST_USER # load handler - jx a0 - -fast_syscall_spill_registers_fixup_return: - - /* When we return here, all registers have been restored (a2: DEPC) */ - - wsr a2, depc # exception address - - /* 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 - - /* Load WB at the time the exception occurred. */ - - rsr a3, sar # WB is still in SAR - neg a3, a3 - wsr a3, windowbase - rsync - - rfde - - -/* - * spill all registers. - * - * This is not a real function. The following conditions must be met: - * - * - must be called with call0. - * - uses a3, a4 and SAR. - * - the last 'valid' register of each frame are clobbered. - * - the caller must have registered a fixup handler - * (or be inside a critical section) - * - PS_EXCM must be set (PS_WOE cleared?) - */ - -ENTRY(_spill_registers) - /* * Rotate ws so that the current windowbase is at bit 0. * Assume ws = xxxwww1yy (www1 current window frame). * Rotate ws right so that a4 = yyxxxwww1. */ - rsr a4, windowbase + rsr a0, windowbase rsr a3, windowstart # a3 = xxxwww1yy - ssr a4 # holds WB - slli a4, a3, WSBITS - or a3, a3, a4 # a3 = xxxwww1yyxxxwww1yy + ssr a0 # holds WB + slli a0, a3, WSBITS + or a3, a3, a0 # a3 = xxxwww1yyxxxwww1yy srl a3, a3 # a3 = 00xxxwww1yyxxxwww1 /* We are done if there are no more than the current register frame. */ extui a3, a3, 1, WSBITS-1 # a3 = 0yyxxxwww - movi a4, (1 << (WSBITS-1)) + movi a0, (1 << (WSBITS-1)) _beqz a3, .Lnospill # only one active frame? jump /* We want 1 at the top, so that we return to the current windowbase */ - or a3, a3, a4 # 1yyxxxwww + or a3, a3, a0 # 1yyxxxwww /* Skip empty frames - get 'oldest' WINDOWSTART-bit. */ wsr a3, windowstart # save shifted windowstart - neg a4, a3 - and a3, a4, a3 # first bit set from right: 000010000 + neg a0, a3 + and a3, a0, a3 # first bit set from right: 000010000 - ffs_ws a4, a3 # a4: shifts to skip empty frames + ffs_ws a0, a3 # a0: shifts to skip empty frames movi a3, WSBITS - sub a4, a3, a4 # WSBITS-a4:number of 0-bits from right - ssr a4 # save in SAR for later. + sub a0, a3, a0 # WSBITS-a0:number of 0-bits from right + ssr a0 # save in SAR for later. rsr a3, windowbase - add a3, a3, a4 + add a3, a3, a0 wsr a3, windowbase rsync @@ -1274,22 +1142,6 @@ ENTRY(_spill_registers) * we have to save 4,8. or 12 registers. */ - _bbsi.l a3, 1, .Lc4 - _bbsi.l a3, 2, .Lc8 - - /* Special case: we have a call12-frame starting at a4. */ - - _bbci.l a3, 3, .Lc12 # bit 3 shouldn't be zero! (Jump to Lc12 first) - - s32e a4, a1, -16 # a1 is valid with an empty spill area - l32e a4, a5, -12 - s32e a8, a4, -48 - mov a8, a4 - l32e a4, a1, -16 - j .Lc12c - -.Lnospill: - ret .Lloop: _bbsi.l a3, 1, .Lc4 _bbci.l a3, 2, .Lc12 @@ -1303,20 +1155,10 @@ ENTRY(_spill_registers) s32e a9, a4, -28 s32e a10, a4, -24 s32e a11, a4, -20 - srli a11, a3, 2 # shift windowbase by 2 rotw 2 _bnei a3, 1, .Lloop - -.Lexit: /* Done. Do the final rotation, set WS, and return. */ - - rotw 1 - rsr a3, windowbase - ssl a3 - movi a3, 1 - sll a3, a3 - wsr a3, windowstart - ret + j .Lexit .Lc4: s32e a4, a9, -16 s32e a5, a9, -12 @@ -1332,11 +1174,11 @@ ENTRY(_spill_registers) /* 12-register frame (call12) */ - l32e a2, a5, -12 - s32e a8, a2, -48 - mov a8, a2 + l32e a0, a5, -12 + s32e a8, a0, -48 + mov a8, a0 -.Lc12c: s32e a9, a8, -44 + s32e a9, a8, -44 s32e a10, a8, -40 s32e a11, a8, -36 s32e a12, a8, -32 @@ -1356,30 +1198,54 @@ ENTRY(_spill_registers) */ rotw 1 - mov a5, a13 + mov a4, a13 rotw -1 - s32e a4, a9, -16 - s32e a5, a9, -12 - s32e a6, a9, -8 - s32e a7, a9, -4 + s32e a4, a8, -16 + s32e a5, a8, -12 + s32e a6, a8, -8 + s32e a7, a8, -4 rotw 3 _beqi a3, 1, .Lexit j .Lloop -.Linvalid_mask: +.Lexit: - /* We get here because of an unrecoverable error in the window - * registers. If we are in user space, we kill the application, - * however, this condition is unrecoverable in kernel space. - */ + /* Done. Do the final rotation and set WS */ - rsr a0, ps - _bbci.l a0, PS_UM_BIT, 1f + rotw 1 + rsr a3, windowbase + ssl a3 + movi a3, 1 + sll a3, a3 + wsr a3, windowstart +.Lnospill: - /* User space: Setup a dummy frame and kill application. + /* Advance PC, restore registers and SAR, and return from exception. */ + + l32i a3, a2, PT_SAR + l32i a0, a2, PT_AREG0 + wsr a3, sar + l32i a3, a2, PT_AREG3 + + /* Restore clobbered registers. */ + + l32i a4, a2, PT_AREG4 + l32i a7, a2, PT_AREG7 + l32i a8, a2, PT_AREG8 + l32i a11, a2, PT_AREG11 + l32i a12, a2, PT_AREG12 + l32i a15, a2, PT_AREG15 + + movi a2, 0 + rfe + +.Linvalid_mask: + + /* We get here because of an unrecoverable error in the window + * registers, so set up a dummy frame and kill the user application. * Note: We assume EXC_TABLE_KSTK contains a valid stack pointer. */ @@ -1403,14 +1269,136 @@ ENTRY(_spill_registers) movi a4, do_exit callx4 a4 -1: /* Kernel space: PANIC! */ + /* shouldn't return, so panic */ wsr a0, excsave1 movi a0, unrecoverable_exception callx0 a0 # should not return 1: j 1b -ENDPROC(_spill_registers) + +ENDPROC(fast_syscall_spill_registers) + +/* Fixup handler. + * + * We get here if the spill routine causes an exception, e.g. tlb miss. + * We basically restore WINDOWBASE and WINDOWSTART to the condition when + * we entered the spill routine and jump to the user exception handler. + * + * Note that we only need to restore the bits in windowstart that have not + * been spilled yet by the _spill_register routine. Luckily, a3 contains a + * rotated windowstart with only those bits set for frames that haven't been + * spilled yet. Because a3 is rotated such that bit 0 represents the register + * frame for the current windowbase - 1, we need to rotate a3 left by the + * value of the current windowbase + 1 and move it to windowstart. + * + * a0: value of depc, original value in depc + * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE + * a3: exctable, original value in excsave1 + */ + +ENTRY(fast_syscall_spill_registers_fixup) + + rsr a2, windowbase # get current windowbase (a2 is saved) + xsr a0, depc # restore depc and a0 + ssl a2 # set shift (32 - WB) + + /* We need to make sure the current registers (a0-a3) are preserved. + * To do this, we simply set the bit for the current window frame + * in WS, so that the exception handlers save them to the task stack. + * + * Note: we use a3 to set the windowbase, so we take a special care + * of it, saving it in the original _spill_registers frame across + * the exception handler call. + */ + + xsr a3, excsave1 # get spill-mask + slli a3, a3, 1 # shift left by one + addi a3, a3, 1 # set the bit for the current window frame + + slli a2, a3, 32-WSBITS + src a2, a3, a2 # a2 = xxwww1yyxxxwww1yy...... + wsr a2, windowstart # set corrected windowstart + + 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 EXC_TABLE_DOUBLE_SAVE) + * depc: depc (we have to return to that address) + * excsave_1: exctable + */ + + wsr a3, windowbase + rsync + + /* We are now in the original frame when we entered _spill_registers: + * a0: return address + * a1: used, stack pointer + * a2: kernel stack pointer + * a3: available + * depc: exception address + * excsave: exctable + * Note: This frame might be the same as above. + */ + + /* Setup stack pointer. */ + + addi a2, a2, -PT_USER_SIZE + s32i a0, a2, PT_AREG0 + + /* Make sure we return to this fixup handler. */ + + movi a3, fast_syscall_spill_registers_fixup_return + s32i a3, a2, PT_DEPC # setup depc + + /* Jump to the exception handler. */ + + rsr a3, excsave1 + 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 + +ENDPROC(fast_syscall_spill_registers_fixup) + +ENTRY(fast_syscall_spill_registers_fixup_return) + + /* When we return here, all registers have been restored (a2: DEPC) */ + + wsr a2, depc # exception address + + /* Restore fixup handler. */ + + 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. */ + + rsr a3, sar # WB is still in SAR + neg a3, a3 + wsr a3, windowbase + rsync + + rsr a3, excsave1 + l32i a3, a3, EXC_TABLE_DOUBLE_SAVE + + rfde + +ENDPROC(fast_syscall_spill_registers_fixup_return) #ifdef CONFIG_MMU /* @@ -1783,6 +1771,43 @@ ENTRY(system_call) ENDPROC(system_call) +/* + * Spill live registers on the kernel stack macro. + * + * Entry condition: ps.woe is set, ps.excm is cleared + * Exit condition: windowstart has single bit set + * May clobber: a12, a13 + */ + .macro spill_registers_kernel + +#if XCHAL_NUM_AREGS > 16 + call12 1f + _j 2f + retw + .align 4 +1: + _entry a1, 48 + addi a12, a0, 3 +#if XCHAL_NUM_AREGS > 32 + .rept (XCHAL_NUM_AREGS - 32) / 12 + _entry a1, 48 + mov a12, a0 + .endr +#endif + _entry a1, 48 +#if XCHAL_NUM_AREGS % 12 == 0 + mov a8, a8 +#elif XCHAL_NUM_AREGS % 12 == 4 + mov a12, a12 +#elif XCHAL_NUM_AREGS % 12 == 8 + mov a4, a4 +#endif + retw +2: +#else + mov a12, a12 +#endif + .endm /* * Task switch. @@ -1795,21 +1820,20 @@ ENTRY(_switch_to) entry a1, 16 - mov a12, a2 # preserve 'prev' (a2) - mov a13, a3 # and 'next' (a3) + mov a10, a2 # preserve 'prev' (a2) + mov a11, a3 # and 'next' (a3) l32i a4, a2, TASK_THREAD_INFO l32i a5, a3, TASK_THREAD_INFO - save_xtregs_user a4 a6 a8 a9 a10 a11 THREAD_XTREGS_USER + save_xtregs_user a4 a6 a8 a9 a12 a13 THREAD_XTREGS_USER - s32i a0, a12, THREAD_RA # save return address - s32i a1, a12, THREAD_SP # save stack pointer + s32i a0, a10, THREAD_RA # save return address + s32i a1, a10, THREAD_SP # save stack pointer /* Disable ints while we manipulate the stack pointer. */ - movi a14, (1 << PS_EXCM_BIT) | LOCKLEVEL - xsr a14, ps + rsil a14, LOCKLEVEL rsr a3, excsave1 rsync s32i a3, a3, EXC_TABLE_FIXUP /* enter critical section */ @@ -1824,7 +1848,7 @@ ENTRY(_switch_to) /* Flush register file. */ - call0 _spill_registers # destroys a3, a4, and SAR + spill_registers_kernel /* Set kernel stack (and leave critical section) * Note: It's save to set it here. The stack will not be overwritten @@ -1840,13 +1864,13 @@ ENTRY(_switch_to) /* restore context of the task 'next' */ - l32i a0, a13, THREAD_RA # restore return address - l32i a1, a13, THREAD_SP # restore stack pointer + l32i a0, a11, THREAD_RA # restore return address + l32i a1, a11, THREAD_SP # restore stack pointer - load_xtregs_user a5 a6 a8 a9 a10 a11 THREAD_XTREGS_USER + load_xtregs_user a5 a6 a8 a9 a12 a13 THREAD_XTREGS_USER wsr a14, ps - mov a2, a12 # return 'prev' + mov a2, a10 # return 'prev' rsync retw |