/* * arch/xtensa/kernel/entry.S * * Low-level exception handling * * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * * Copyright (C) 2004-2007 by Tensilica Inc. * * Chris Zankel <chris@zankel.net> * */ #include <linux/linkage.h>#include <asm/asm-offsets.h>#include <asm/processor.h>#include <asm/coprocessor.h>#include <asm/thread_info.h>#include <asm/uaccess.h>#include <asm/unistd.h>#include <asm/ptrace.h>#include <asm/current.h>#include <asm/pgtable.h>#include <asm/page.h>#include <asm/signal.h>#include <asm/tlbflush.h>#include <variant/tie-asm.h> /* Unimplemented features. */ #undef KERNEL_STACK_OVERFLOW_CHECK#undef PREEMPTIBLE_KERNEL#undef ALLOCA_EXCEPTION_IN_IRAM /* Not well tested. * * - fast_coprocessor */ /* * Macro to find first bit set in WINDOWBASE from the left + 1 * * 100....0 -> 1 * 010....0 -> 2 * 000....1 -> WSBITS */ .macro ffs_ws bit mask #if XCHAL_HAVE_NSA nsau \bit, \mask # 32-WSBITS ... 31 (32 iff 0) addi \bit, \bit, WSBITS - 32 + 1 # uppest bit set -> return 1#else movi \bit, WSBITS#if WSBITS > 16 _bltui \mask, 0x10000, 99f addi \bit, \bit, -16 extui \mask, \mask, 16, 16#endif#if WSBITS > 899: _bltui \mask, 0x100, 99f addi \bit, \bit, -8 srli \mask, \mask, 8#endif99: _bltui \mask, 0x10, 99f addi \bit, \bit, -4 srli \mask, \mask, 499: _bltui \mask, 0x4, 99f addi \bit, \bit, -2 srli \mask, \mask, 299: _bltui \mask, 0x2, 99f addi \bit, \bit, -199: #endif .endm /* ----------------- DEFAULT FIRST LEVEL EXCEPTION HANDLERS ----------------- */ /* * First-level exception handler for user exceptions. * Save some special registers, extra states and all registers in the AR * register file that were in use in the user task, and jump to the common * exception code. * We save SAR (used to calculate WMASK), and WB and WS (we don't have to * save them for kernel exceptions). * * Entry condition for user_exception: * * a0: trashed, original value saved on stack (PT_AREG0) * a1: a1 * a2: new stack pointer, original value in depc * a3: dispatch table * depc: a2, original value saved on stack (PT_DEPC) * excsave1: a3 * * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception * * Entry condition for _user_exception: * * a0-a3 and depc have been saved to PT_AREG0...PT_AREG3 and PT_DEPC * excsave has been restored, and * stack pointer (a1) has been set. * * Note: _user_exception might be at an odd address. Don't use call0..call12 */ ENTRY(user_exception) /* Save a2, a3, and depc, restore excsave_1 and set SP. */ xsr a3, EXCSAVE_1 rsr a0, DEPC s32i a1, a2, PT_AREG1 s32i a0, a2, PT_AREG2 s32i a3, a2, PT_AREG3 mov a1, a2 .globl _user_exception_user_exception: /* Save SAR and turn off single stepping */ movi a2, 0 rsr a3, SAR xsr a2, ICOUNTLEVEL s32i a3, a1, PT_SAR s32i a2, a1, PT_ICOUNTLEVEL /* Rotate ws so that the current windowbase is at bit0. */ /* Assume ws = xxwww1yyyy. Rotate ws right, so that a2 = yyyyxxwww1 */ rsr a2, WINDOWBASE rsr a3, WINDOWSTART ssr a2 s32i a2, a1, PT_WINDOWBASE s32i a3, a1, PT_WINDOWSTART slli a2, a3, 32-WSBITS src a2, a3, a2 srli a2, a2, 32-WSBITS s32i a2, a1, PT_WMASK # needed for restoring registers /* Save only live registers. */ _bbsi.l a2, 1, 1f s32i a4, a1, PT_AREG4 s32i a5, a1, PT_AREG5 s32i a6, a1, PT_AREG6 s32i a7, a1, PT_AREG7 _bbsi.l a2, 2, 1f s32i a8, a1, PT_AREG8 s32i a9, a1, PT_AREG9 s32i a10, a1, PT_AREG10 s32i a11, a1, PT_AREG11 _bbsi.l a2, 3, 1f s32i a12, a1, PT_AREG12 s32i a13, a1, PT_AREG13 s32i a14, a1, PT_AREG14 s32i a15, a1, PT_AREG15 _bnei a2, 1, 1f # only one valid frame? /* Only one valid frame, skip saving regs. */ j 2f /* Save the remaining registers. * We have to save all registers up to the first '1' from * the right, except the current frame (bit 0). * Assume a2 is: 001001000110001 * All register frames starting from the top field to the marked '1' * must be saved. */ 1: addi a3, a2, -1 # eliminate '1' in bit 0: yyyyxxww0 neg a3, a3 # yyyyxxww0 -> YYYYXXWW1+1 and a3, a3, a2 # max. only one bit is set /* Find number of frames to save */ ffs_ws a0, a3 # number of frames to the '1' from left /* Store information into WMASK: * bits 0..3: xxx1 masked lower 4 bits of the rotated windowstart, * bits 4...: number of valid 4-register frames */ slli a3, a0, 4 # number of frames to save in bits 8..4 extui a2, a2, 0, 4 # mask for the first 16 registers or a2, a3, a2 s32i a2, a1, PT_WMASK # needed when we restore the reg-file /* Save 4 registers at a time */ 1: rotw -1 s32i a0, a5, PT_AREG_END - 16 s32i a1, a5, PT_AREG_END - 12 s32i a2, a5, PT_AREG_END - 8 s32i a3, a5, PT_AREG_END - 4 addi a0, a4, -1 addi a1, a5, -16 _bnez a0, 1b /* WINDOWBASE still in SAR! */ rsr a2, SAR # original WINDOWBASE movi a3, 1 ssl a2 sll a3, a3 wsr a3, WINDOWSTART # set corresponding WINDOWSTART bit wsr a2, WINDOWBASE # and WINDOWSTART rsync /* We are back to the original stack pointer (a1) */ 2: /* Now, jump to the common exception handler. */ j common_exception /* * First-level exit handler for kernel exceptions * Save special registers and the live window frame. * Note: Even though we changes the stack pointer, we don't have to do a * MOVSP here, as we do that when we return from the exception. * (See comment in the kernel exception exit code) * * Entry condition for kernel_exception: * * a0: trashed, original value saved on stack (PT_AREG0) * a1: a1 * a2: new stack pointer, original in DEPC * a3: dispatch table * depc: a2, original value saved on stack (PT_DEPC) * excsave_1: a3 * * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception * * Entry condition for _kernel_exception: * * a0-a3 and depc have been saved to PT_AREG0...PT_AREG3 and PT_DEPC * excsave has been restored, and * stack pointer (a1) has been set. * * Note: _kernel_exception might be at an odd address. Don't use call0..call12 */ ENTRY(kernel_exception) /* Save a0, a2, a3, DEPC and set SP. */ xsr a3, EXCSAVE_1 # restore a3, excsave_1 rsr a0, DEPC # get a2 s32i a1, a2, PT_AREG1 s32i a0, a2, PT_AREG2 s32i a3, a2, PT_AREG3 mov a1, a2 .globl _kernel_exception_kernel_exception: /* Save SAR and turn off single stepping */ movi a2, 0 rsr a3, SAR xsr a2, ICOUNTLEVEL s32i a3, a1, PT_SAR s32i a2, a1, PT_ICOUNTLEVEL /* Rotate ws so that the current windowbase is at bit0. */ /* Assume ws = xxwww1yyyy. Rotate ws right, so that a2 = yyyyxxwww1 */ rsr a2, WINDOWBASE # don't need to save these, we only rsr a3, WINDOWSTART # need shifted windowstart: windowmask ssr a2 slli a2, a3, 32-WSBITS src a2, a3, a2 srli a2, a2, 32-WSBITS s32i a2, a1, PT_WMASK # needed for kernel_exception_exit /* Save only the live window-frame */ _bbsi.l a2, 1, 1f s32i a4, a1, PT_AREG4 s32i a5, a1, PT_AREG5 s32i a6, a1, PT_AREG6 s32i a7, a1, PT_AREG7 _bbsi.l a2, 2, 1f s32i a8, a1, PT_AREG8 s32i a9, a1, PT_AREG9 s32i a10, a1, PT_AREG10 s32i a11, a1, PT_AREG11 _bbsi.l a2, 3, 1f s32i a12, a1, PT_AREG12 s32i a13, a1, PT_AREG13 s32i a14, a1, PT_AREG14 s32i a15, a1, PT_AREG15 1: #ifdef KERNEL_STACK_OVERFLOW_CHECK /* Stack overflow check, for debugging */ extui a2, a1, TASK_SIZE_BITS,XX movi a3, SIZE?? _bge a2, a3, out_of_stack_panic #endif /* * This is the common exception handler. * We get here from the user exception handler or simply by falling through * from the kernel exception handler. * Save the remaining special registers, switch to kernel mode, and jump * to the second-level exception handler. * */ common_exception: /* Save some registers, disable loops and clear the syscall flag. */ rsr a2, DEBUGCAUSE rsr a3, EPC_1 s32i a2, a1, PT_DEBUGCAUSE s32i a3, a1, PT_PC movi a2, -1 rsr a3, EXCVADDR s32i a2, a1, PT_SYSCALL movi a2, 0 s32i a3, a1, PT_EXCVADDR xsr a2, LCOUNT s32i a2, a1, PT_LCOUNT /* It is now save to restore the EXC_TABLE_FIXUP variable. */ rsr a0, EXCCAUSE movi a3, 0 rsr a2, EXCSAVE_1 s32i a0, a1, PT_EXCCAUSE s32i a3, a2, EXC_TABLE_FIXUP /* All unrecoverable states are saved on stack, now, and a1 is valid, * so we can allow exceptions and interrupts (*) again. * Set PS(EXCM = 0, UM = 0, RING = 0, OWB = 0, WOE = 1, INTLEVEL = X) * * (*) We only allow interrupts if PS.INTLEVEL was not set to 1 before * (interrupts disabled) and if this exception is not an interrupt. */ rsr a3, PS addi a0, a0, -4 movi a2, 1 extui a3, a3, 0, 1 # a3 = PS.INTLEVEL[0] moveqz a3, a2, a0 # a3 = 1 iff interrupt exception movi a2, 1 << PS_WOE_BIT or a3, a3, a2 rsr a0, EXCCAUSE xsr a3, PS s32i a3, a1, PT_PS # save ps /* Save LBEG, LEND */ rsr a2, LBEG rsr a3, LEND s32i a2, a1, PT_LBEG s32i a3, a1, PT_LEND /* Save optional registers. */ save_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT /* Go to second-level dispatcher. Set up parameters to pass to the * exception handler and call the exception handler. */ movi a4, exc_table mov a6, a1 # pass stack frame mov a7, a0 # pass EXCCAUSE addx4 a4, a0, a4 l32i a4, a4, EXC_TABLE_DEFAULT # load handler /* Call the second-level handler */ callx4 a4 /* Jump here for exception exit */ common_exception_return: /* Jump if we are returning from kernel exceptions. */ 1: l32i a3, a1, PT_PS _bbci.l a3, PS_UM_BIT, 4f /* Specific to a user exception exit: * We need to check some flags for signal handling and rescheduling, * and have to restore WB and WS, extra states, and all registers * in the register file that were in use in the user task. * Note that we don't disable interrupts here. */ GET_THREAD_INFO(a2,a1) l32i a4, a2, TI_FLAGS _bbsi.l a4, TIF_NEED_RESCHED, 3f _bbci.l a4, TIF_SIGPENDING, 4f l32i a4, a1, PT_DEPC bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 4f /* Call do_signal() */ movi a4, do_signal # int do_signal(struct pt_regs*, sigset_t*) mov a6, a1 movi a7, 0 callx4 a4 j 1b 3: /* Reschedule */ movi a4, schedule # void schedule (void) callx4 a4 j 1b 4: /* Restore optional registers. */ load_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT wsr a3, PS /* disable interrupts */ _bbci.l a3, PS_UM_BIT, kernel_exception_exit user_exception_exit: /* Restore the state of the task and return from the exception. */ /* Switch to the user thread WINDOWBASE. Save SP temporarily in DEPC */ l32i a2, a1, PT_WINDOWBASE l32i a3, a1, PT_WINDOWSTART wsr a1, DEPC # use DEPC as temp storage wsr a3, WINDOWSTART # restore WINDOWSTART ssr a2 # preserve user's WB in the SAR wsr a2, WINDOWBASE # switch to user's saved WB rsync rsr a1, DEPC # restore stack pointer l32i a2, a1, PT_WMASK # register frames saved (in bits 4...9) rotw -1 # we restore a4..a7 _bltui a6, 16, 1f # only have to restore current window? /* The working registers are a0 and a3. We are restoring to * a4..a7. Be careful not to destroy what we have just restored. * Note: wmask has the format YYYYM: * Y: number of registers saved in groups of 4 * M: 4 bit mask of first 16 registers */ mov a2, a6 mov a3, a5 2: rotw -1 # a0..a3 become a4..a7 addi a3, a7, -4*4 # next iteration addi a2, a6, -16 # decrementing Y in WMASK l32i a4, a3, PT_AREG_END + 0 l32i a5, a3, PT_AREG_END + 4 l32i a6, a3, PT_AREG_END + 8 l32i a7, a3, PT_AREG_END + 12 _bgeui a2, 16, 2b /* Clear unrestored registers (don't leak anything to user-land */ 1: rsr a0, WINDOWBASE rsr a3, SAR sub a3, a0, a3 beqz a3, 2f extui a3, a3, 0, WBBITS 1: rotw -1 addi a3, a7, -1 movi a4, 0 movi a5, 0 movi a6, 0 movi a7, 0 bgei a3, 1, 1b /* We are back were we were when we started. * Note: a2 still contains WMASK (if we've returned to the original * frame where we had loaded a2), or at least the lower 4 bits * (if we have restored WSBITS-1 frames). */ 2: j common_exception_exit /* This is the kernel exception exit.Lines 1–500 of 1960. Load more
/* * arch/xtensa/kernel/entry.S * * Low-level exception handling * * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * * Copyright (C) 2004-2007 by Tensilica Inc. * * Chris Zankel <chris@zankel.net> * */ #include <linux/linkage.h> #include <asm/asm-offsets.h> #include <asm/processor.h> #include <asm/coprocessor.h> #include <asm/thread_info.h> #include <asm/uaccess.h> #include <asm/unistd.h> #include <asm/ptrace.h> #include <asm/current.h> #include <asm/pgtable.h> #include <asm/page.h> #include <asm/signal.h> #include <asm/tlbflush.h> #include <variant/tie-asm.h> /* Unimplemented features. */ #undef KERNEL_STACK_OVERFLOW_CHECK #undef PREEMPTIBLE_KERNEL #undef ALLOCA_EXCEPTION_IN_IRAM /* Not well tested. * * - fast_coprocessor */ /* * Macro to find first bit set in WINDOWBASE from the left + 1 * * 100....0 -> 1 * 010....0 -> 2 * 000....1 -> WSBITS */ .macro ffs_ws bit mask #if XCHAL_HAVE_NSA nsau \bit, \mask # 32-WSBITS ... 31 (32 iff 0) addi \bit, \bit, WSBITS - 32 + 1 # uppest bit set -> return 1 #else movi \bit, WSBITS #if WSBITS > 16 _bltui \mask, 0x10000, 99f addi \bit, \bit, -16 extui \mask, \mask, 16, 16 #endif #if WSBITS > 8 99: _bltui \mask, 0x100, 99f addi \bit, \bit, -8 srli \mask, \mask, 8 #endif 99: _bltui \mask, 0x10, 99f addi \bit, \bit, -4 srli \mask, \mask, 4 99: _bltui \mask, 0x4, 99f addi \bit, \bit, -2 srli \mask, \mask, 2 99: _bltui \mask, 0x2, 99f addi \bit, \bit, -1 99: #endif .endm /* ----------------- DEFAULT FIRST LEVEL EXCEPTION HANDLERS ----------------- */ /* * First-level exception handler for user exceptions. * Save some special registers, extra states and all registers in the AR * register file that were in use in the user task, and jump to the common * exception code. * We save SAR (used to calculate WMASK), and WB and WS (we don't have to * save them for kernel exceptions). * * Entry condition for user_exception: * * a0: trashed, original value saved on stack (PT_AREG0) * a1: a1 * a2: new stack pointer, original value in depc * a3: dispatch table * depc: a2, original value saved on stack (PT_DEPC) * excsave1: a3 * * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception * * Entry condition for _user_exception: * * a0-a3 and depc have been saved to PT_AREG0...PT_AREG3 and PT_DEPC * excsave has been restored, and * stack pointer (a1) has been set. * * Note: _user_exception might be at an odd address. Don't use call0..call12 */ ENTRY(user_exception) /* Save a2, a3, and depc, restore excsave_1 and set SP. */ xsr a3, EXCSAVE_1 rsr a0, DEPC s32i a1, a2, PT_AREG1 s32i a0, a2, PT_AREG2 s32i a3, a2, PT_AREG3 mov a1, a2 .globl _user_exception _user_exception: /* Save SAR and turn off single stepping */ movi a2, 0 rsr a3, SAR xsr a2, ICOUNTLEVEL s32i a3, a1, PT_SAR s32i a2, a1, PT_ICOUNTLEVEL /* Rotate ws so that the current windowbase is at bit0. */ /* Assume ws = xxwww1yyyy. Rotate ws right, so that a2 = yyyyxxwww1 */ rsr a2, WINDOWBASE rsr a3, WINDOWSTART ssr a2 s32i a2, a1, PT_WINDOWBASE s32i a3, a1, PT_WINDOWSTART slli a2, a3, 32-WSBITS src a2, a3, a2 srli a2, a2, 32-WSBITS s32i a2, a1, PT_WMASK # needed for restoring registers /* Save only live registers. */ _bbsi.l a2, 1, 1f s32i a4, a1, PT_AREG4 s32i a5, a1, PT_AREG5 s32i a6, a1, PT_AREG6 s32i a7, a1, PT_AREG7 _bbsi.l a2, 2, 1f s32i a8, a1, PT_AREG8 s32i a9, a1, PT_AREG9 s32i a10, a1, PT_AREG10 s32i a11, a1, PT_AREG11 _bbsi.l a2, 3, 1f s32i a12, a1, PT_AREG12 s32i a13, a1, PT_AREG13 s32i a14, a1, PT_AREG14 s32i a15, a1, PT_AREG15 _bnei a2, 1, 1f # only one valid frame? /* Only one valid frame, skip saving regs. */ j 2f /* Save the remaining registers. * We have to save all registers up to the first '1' from * the right, except the current frame (bit 0). * Assume a2 is: 001001000110001 * All register frames starting from the top field to the marked '1' * must be saved. */ 1: addi a3, a2, -1 # eliminate '1' in bit 0: yyyyxxww0 neg a3, a3 # yyyyxxww0 -> YYYYXXWW1+1 and a3, a3, a2 # max. only one bit is set /* Find number of frames to save */ ffs_ws a0, a3 # number of frames to the '1' from left /* Store information into WMASK: * bits 0..3: xxx1 masked lower 4 bits of the rotated windowstart, * bits 4...: number of valid 4-register frames */ slli a3, a0, 4 # number of frames to save in bits 8..4 extui a2, a2, 0, 4 # mask for the first 16 registers or a2, a3, a2 s32i a2, a1, PT_WMASK # needed when we restore the reg-file /* Save 4 registers at a time */ 1: rotw -1 s32i a0, a5, PT_AREG_END - 16 s32i a1, a5, PT_AREG_END - 12 s32i a2, a5, PT_AREG_END - 8 s32i a3, a5, PT_AREG_END - 4 addi a0, a4, -1 addi a1, a5, -16 _bnez a0, 1b /* WINDOWBASE still in SAR! */ rsr a2, SAR # original WINDOWBASE movi a3, 1 ssl a2 sll a3, a3 wsr a3, WINDOWSTART # set corresponding WINDOWSTART bit wsr a2, WINDOWBASE # and WINDOWSTART rsync /* We are back to the original stack pointer (a1) */ 2: /* Now, jump to the common exception handler. */ j common_exception /* * First-level exit handler for kernel exceptions * Save special registers and the live window frame. * Note: Even though we changes the stack pointer, we don't have to do a * MOVSP here, as we do that when we return from the exception. * (See comment in the kernel exception exit code) * * Entry condition for kernel_exception: * * a0: trashed, original value saved on stack (PT_AREG0) * a1: a1 * a2: new stack pointer, original in DEPC * a3: dispatch table * depc: a2, original value saved on stack (PT_DEPC) * excsave_1: a3 * * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception * * Entry condition for _kernel_exception: * * a0-a3 and depc have been saved to PT_AREG0...PT_AREG3 and PT_DEPC * excsave has been restored, and * stack pointer (a1) has been set. * * Note: _kernel_exception might be at an odd address. Don't use call0..call12 */ ENTRY(kernel_exception) /* Save a0, a2, a3, DEPC and set SP. */ xsr a3, EXCSAVE_1 # restore a3, excsave_1 rsr a0, DEPC # get a2 s32i a1, a2, PT_AREG1 s32i a0, a2, PT_AREG2 s32i a3, a2, PT_AREG3 mov a1, a2 .globl _kernel_exception _kernel_exception: /* Save SAR and turn off single stepping */ movi a2, 0 rsr a3, SAR xsr a2, ICOUNTLEVEL s32i a3, a1, PT_SAR s32i a2, a1, PT_ICOUNTLEVEL /* Rotate ws so that the current windowbase is at bit0. */ /* Assume ws = xxwww1yyyy. Rotate ws right, so that a2 = yyyyxxwww1 */ rsr a2, WINDOWBASE # don't need to save these, we only rsr a3, WINDOWSTART # need shifted windowstart: windowmask ssr a2 slli a2, a3, 32-WSBITS src a2, a3, a2 srli a2, a2, 32-WSBITS s32i a2, a1, PT_WMASK # needed for kernel_exception_exit /* Save only the live window-frame */ _bbsi.l a2, 1, 1f s32i a4, a1, PT_AREG4 s32i a5, a1, PT_AREG5 s32i a6, a1, PT_AREG6 s32i a7, a1, PT_AREG7 _bbsi.l a2, 2, 1f s32i a8, a1, PT_AREG8 s32i a9, a1, PT_AREG9 s32i a10, a1, PT_AREG10 s32i a11, a1, PT_AREG11 _bbsi.l a2, 3, 1f s32i a12, a1, PT_AREG12 s32i a13, a1, PT_AREG13 s32i a14, a1, PT_AREG14 s32i a15, a1, PT_AREG15 1: #ifdef KERNEL_STACK_OVERFLOW_CHECK /* Stack overflow check, for debugging */ extui a2, a1, TASK_SIZE_BITS,XX movi a3, SIZE?? _bge a2, a3, out_of_stack_panic #endif /* * This is the common exception handler. * We get here from the user exception handler or simply by falling through * from the kernel exception handler. * Save the remaining special registers, switch to kernel mode, and jump * to the second-level exception handler. * */ common_exception: /* Save some registers, disable loops and clear the syscall flag. */ rsr a2, DEBUGCAUSE rsr a3, EPC_1 s32i a2, a1, PT_DEBUGCAUSE s32i a3, a1, PT_PC movi a2, -1 rsr a3, EXCVADDR s32i a2, a1, PT_SYSCALL movi a2, 0 s32i a3, a1, PT_EXCVADDR xsr a2, LCOUNT s32i a2, a1, PT_LCOUNT /* It is now save to restore the EXC_TABLE_FIXUP variable. */ rsr a0, EXCCAUSE movi a3, 0 rsr a2, EXCSAVE_1 s32i a0, a1, PT_EXCCAUSE s32i a3, a2, EXC_TABLE_FIXUP /* All unrecoverable states are saved on stack, now, and a1 is valid, * so we can allow exceptions and interrupts (*) again. * Set PS(EXCM = 0, UM = 0, RING = 0, OWB = 0, WOE = 1, INTLEVEL = X) * * (*) We only allow interrupts if PS.INTLEVEL was not set to 1 before * (interrupts disabled) and if this exception is not an interrupt. */ rsr a3, PS addi a0, a0, -4 movi a2, 1 extui a3, a3, 0, 1 # a3 = PS.INTLEVEL[0] moveqz a3, a2, a0 # a3 = 1 iff interrupt exception movi a2, 1 << PS_WOE_BIT or a3, a3, a2 rsr a0, EXCCAUSE xsr a3, PS s32i a3, a1, PT_PS # save ps /* Save LBEG, LEND */ rsr a2, LBEG rsr a3, LEND s32i a2, a1, PT_LBEG s32i a3, a1, PT_LEND /* Save optional registers. */ save_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT /* Go to second-level dispatcher. Set up parameters to pass to the * exception handler and call the exception handler. */ movi a4, exc_table mov a6, a1 # pass stack frame mov a7, a0 # pass EXCCAUSE addx4 a4, a0, a4 l32i a4, a4, EXC_TABLE_DEFAULT # load handler /* Call the second-level handler */ callx4 a4 /* Jump here for exception exit */ common_exception_return: /* Jump if we are returning from kernel exceptions. */ 1: l32i a3, a1, PT_PS _bbci.l a3, PS_UM_BIT, 4f /* Specific to a user exception exit: * We need to check some flags for signal handling and rescheduling, * and have to restore WB and WS, extra states, and all registers * in the register file that were in use in the user task. * Note that we don't disable interrupts here. */ GET_THREAD_INFO(a2,a1) l32i a4, a2, TI_FLAGS _bbsi.l a4, TIF_NEED_RESCHED, 3f _bbci.l a4, TIF_SIGPENDING, 4f l32i a4, a1, PT_DEPC bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 4f /* Call do_signal() */ movi a4, do_signal # int do_signal(struct pt_regs*, sigset_t*) mov a6, a1 movi a7, 0 callx4 a4 j 1b 3: /* Reschedule */ movi a4, schedule # void schedule (void) callx4 a4 j 1b 4: /* Restore optional registers. */ load_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT wsr a3, PS /* disable interrupts */ _bbci.l a3, PS_UM_BIT, kernel_exception_exit user_exception_exit: /* Restore the state of the task and return from the exception. */ /* Switch to the user thread WINDOWBASE. Save SP temporarily in DEPC */ l32i a2, a1, PT_WINDOWBASE l32i a3, a1, PT_WINDOWSTART wsr a1, DEPC # use DEPC as temp storage wsr a3, WINDOWSTART # restore WINDOWSTART ssr a2 # preserve user's WB in the SAR wsr a2, WINDOWBASE # switch to user's saved WB rsync rsr a1, DEPC # restore stack pointer l32i a2, a1, PT_WMASK # register frames saved (in bits 4...9) rotw -1 # we restore a4..a7 _bltui a6, 16, 1f # only have to restore current window? /* The working registers are a0 and a3. We are restoring to * a4..a7. Be careful not to destroy what we have just restored. * Note: wmask has the format YYYYM: * Y: number of registers saved in groups of 4 * M: 4 bit mask of first 16 registers */ mov a2, a6 mov a3, a5 2: rotw -1 # a0..a3 become a4..a7 addi a3, a7, -4*4 # next iteration addi a2, a6, -16 # decrementing Y in WMASK l32i a4, a3, PT_AREG_END + 0 l32i a5, a3, PT_AREG_END + 4 l32i a6, a3, PT_AREG_END + 8 l32i a7, a3, PT_AREG_END + 12 _bgeui a2, 16, 2b /* Clear unrestored registers (don't leak anything to user-land */ 1: rsr a0, WINDOWBASE rsr a3, SAR sub a3, a0, a3 beqz a3, 2f extui a3, a3, 0, WBBITS 1: rotw -1 addi a3, a7, -1 movi a4, 0 movi a5, 0 movi a6, 0 movi a7, 0 bgei a3, 1, 1b /* We are back were we were when we started. * Note: a2 still contains WMASK (if we've returned to the original * frame where we had loaded a2), or at least the lower 4 bits * (if we have restored WSBITS-1 frames). */ 2: j common_exception_exit /* This is the kernel exception exit.