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Diffstat (limited to 'arch/arc/kernel/entry-compact.S')
| -rw-r--r-- | arch/arc/kernel/entry-compact.S | 403 |
1 files changed, 403 insertions, 0 deletions
diff --git a/arch/arc/kernel/entry-compact.S b/arch/arc/kernel/entry-compact.S new file mode 100644 index 000000000..5cb0cd7e4 --- /dev/null +++ b/arch/arc/kernel/entry-compact.S @@ -0,0 +1,403 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARCompact ISA + * + * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com) + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + * + * vineetg: May 2011 + * -Userspace unaligned access emulation + * + * vineetg: Feb 2011 (ptrace low level code fixes) + * -traced syscall return code (r0) was not saved into pt_regs for restoring + * into user reg-file when traded task rets to user space. + * -syscalls needing arch-wrappers (mainly for passing sp as pt_regs) + * were not invoking post-syscall trace hook (jumping directly into + * ret_from_system_call) + * + * vineetg: Nov 2010: + * -Vector table jumps (@8 bytes) converted into branches (@4 bytes) + * -To maintain the slot size of 8 bytes/vector, added nop, which is + * not executed at runtime. + * + * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK) + * -do_signal()invoked upon TIF_RESTORE_SIGMASK as well + * -Wrappers for sys_{,rt_}sigsuspend() no longer needed as they don't + * need ptregs anymore + * + * Vineetg: Oct 2009 + * -In a rare scenario, Process gets a Priv-V exception and gets scheduled + * out. Since we don't do FAKE RTIE for Priv-V, CPU exception state remains + * active (AE bit enabled). This causes a double fault for a subseq valid + * exception. Thus FAKE RTIE needed in low level Priv-Violation handler. + * Instr Error could also cause similar scenario, so same there as well. + * + * Vineetg: March 2009 (Supporting 2 levels of Interrupts) + * + * Vineetg: Aug 28th 2008: Bug #94984 + * -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap + * Normally CPU does this automatically, however when doing FAKE rtie, + * we need to explicitly do this. The problem in macros + * FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit + * was being "CLEARED" rather then "SET". Since it is Loop INHIBIT Bit, + * setting it and not clearing it clears ZOL context + * + * Vineetg: May 16th, 2008 + * - r25 now contains the Current Task when in kernel + * + * Vineetg: Dec 22, 2007 + * Minor Surgery of Low Level ISR to make it SMP safe + * - MMU_SCRATCH0 Reg used for freeing up r9 in Level 1 ISR + * - _current_task is made an array of NR_CPUS + * - Access of _current_task wrapped inside a macro so that if hardware + * team agrees for a dedicated reg, no other code is touched + * + * Amit Bhor, Rahul Trivedi, Kanika Nema, Sameer Dhavale : Codito Tech 2004 + */ + +#include <linux/errno.h> +#include <linux/linkage.h> /* {ENTRY,EXIT} */ +#include <asm/entry.h> +#include <asm/irqflags.h> + + .cpu A7 + +;############################ Vector Table ################################# + +.macro VECTOR lbl +#if 1 /* Just in case, build breaks */ + j \lbl +#else + b \lbl + nop +#endif +.endm + + .section .vector, "ax",@progbits + .align 4 + +/* Each entry in the vector table must occupy 2 words. Since it is a jump + * across sections (.vector to .text) we are guaranteed that 'j somewhere' + * will use the 'j limm' form of the instruction as long as somewhere is in + * a section other than .vector. + */ + +; ********* Critical System Events ********************** +VECTOR res_service ; 0x0, Reset Vector (0x0) +VECTOR mem_service ; 0x8, Mem exception (0x1) +VECTOR instr_service ; 0x10, Instrn Error (0x2) + +; ******************** Device ISRs ********************** +#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS +VECTOR handle_interrupt_level2 +#else +VECTOR handle_interrupt_level1 +#endif + +.rept 28 +VECTOR handle_interrupt_level1 ; Other devices +.endr + +/* FOR ARC600: timer = 0x3, uart = 0x8, emac = 0x10 */ + +; ******************** Exceptions ********************** +VECTOR EV_MachineCheck ; 0x100, Fatal Machine check (0x20) +VECTOR EV_TLBMissI ; 0x108, Instruction TLB miss (0x21) +VECTOR EV_TLBMissD ; 0x110, Data TLB miss (0x22) +VECTOR EV_TLBProtV ; 0x118, Protection Violation (0x23) + ; or Misaligned Access +VECTOR EV_PrivilegeV ; 0x120, Privilege Violation (0x24) +VECTOR EV_Trap ; 0x128, Trap exception (0x25) +VECTOR EV_Extension ; 0x130, Extn Instruction Excp (0x26) + +.rept 24 +VECTOR reserved ; Reserved Exceptions +.endr + + +;##################### Scratch Mem for IRQ stack switching ############# + +ARCFP_DATA int1_saved_reg + .align 32 + .type int1_saved_reg, @object + .size int1_saved_reg, 4 +int1_saved_reg: + .zero 4 + +/* Each Interrupt level needs its own scratch */ +ARCFP_DATA int2_saved_reg + .type int2_saved_reg, @object + .size int2_saved_reg, 4 +int2_saved_reg: + .zero 4 + +; --------------------------------------------- + .section .text, "ax",@progbits + + +reserved: + flag 1 ; Unexpected event, halt + +;##################### Interrupt Handling ############################## + +#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS +; --------------------------------------------- +; Level 2 ISR: Can interrupt a Level 1 ISR +; --------------------------------------------- +ENTRY(handle_interrupt_level2) + + INTERRUPT_PROLOGUE 2 + + ;------------------------------------------------------ + ; if L2 IRQ interrupted a L1 ISR, disable preemption + ; + ; This is to avoid a potential L1-L2-L1 scenario + ; -L1 IRQ taken + ; -L2 interrupts L1 (before L1 ISR could run) + ; -preemption off IRQ, user task in syscall picked to run + ; -RTIE to userspace + ; Returns from L2 context fine + ; But both L1 and L2 re-enabled, so another L1 can be taken + ; while prev L1 is still unserviced + ; + ;------------------------------------------------------ + + ; L2 interrupting L1 implies both L2 and L1 active + ; However both A2 and A1 are NOT set in STATUS32, thus + ; need to check STATUS32_L2 to determine if L1 was active + + ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs) + bbit0 r9, STATUS_A1_BIT, 1f ; L1 not active when L2 IRQ, so normal + + ; bump thread_info->preempt_count (Disable preemption) + GET_CURR_THR_INFO_FROM_SP r10 + ld r9, [r10, THREAD_INFO_PREEMPT_COUNT] + add r9, r9, 1 + st r9, [r10, THREAD_INFO_PREEMPT_COUNT] + +1: + ;------------------------------------------------------ + ; setup params for Linux common ISR and invoke it + ;------------------------------------------------------ + lr r0, [icause2] + and r0, r0, 0x1f + + bl.d @arch_do_IRQ + mov r1, sp + + mov r8,0x2 + sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg + + b ret_from_exception + +END(handle_interrupt_level2) + +#endif + +; --------------------------------------------- +; User Mode Memory Bus Error Interrupt Handler +; (Kernel mode memory errors handled via separate exception vectors) +; --------------------------------------------- +ENTRY(mem_service) + + INTERRUPT_PROLOGUE 2 + + mov r0, ilink2 + mov r1, sp + + ; User process needs to be killed with SIGBUS, but first need to get + ; out of the L2 interrupt context (drop to pure kernel mode) and jump + ; off to "C" code where SIGBUS in enqueued + lr r3, [status32] + bclr r3, r3, STATUS_A2_BIT + or r3, r3, (STATUS_E1_MASK|STATUS_E2_MASK) + sr r3, [status32_l2] + mov ilink2, 1f + rtie +1: + bl do_memory_error + b ret_from_exception +END(mem_service) + +; --------------------------------------------- +; Level 1 ISR +; --------------------------------------------- +ENTRY(handle_interrupt_level1) + + INTERRUPT_PROLOGUE 1 + + lr r0, [icause1] + and r0, r0, 0x1f + +#ifdef CONFIG_TRACE_IRQFLAGS + ; icause1 needs to be read early, before calling tracing, which + ; can clobber scratch regs, hence use of stack to stash it + push r0 + TRACE_ASM_IRQ_DISABLE + pop r0 +#endif + + bl.d @arch_do_IRQ + mov r1, sp + + mov r8,0x1 + sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg + + b ret_from_exception +END(handle_interrupt_level1) + +;################### Non TLB Exception Handling ############################# + +; --------------------------------------------- +; Protection Violation Exception Handler +; --------------------------------------------- + +ENTRY(EV_TLBProtV) + + EXCEPTION_PROLOGUE + + mov r2, r10 ; ECR set into r10 already + lr r0, [efa] ; Faulting Data address (not part of pt_regs saved above) + + ; Exception auto-disables further Intr/exceptions. + ; Re-enable them by pretending to return from exception + ; (so rest of handler executes in pure K mode) + + FAKE_RET_FROM_EXCPN + + mov r1, sp ; Handle to pt_regs + + ;------ (5) Type of Protection Violation? ---------- + ; + ; ProtV Hardware Exception is triggered for Access Faults of 2 types + ; -Access Violation : 00_23_(00|01|02|03)_00 + ; x r w r+w + ; -Unaligned Access : 00_23_04_00 + ; + bbit1 r2, ECR_C_BIT_PROTV_MISALIG_DATA, 4f + + ;========= (6a) Access Violation Processing ======== + bl do_page_fault + b ret_from_exception + + ;========== (6b) Non aligned access ============ +4: + + SAVE_CALLEE_SAVED_USER + mov r2, sp ; callee_regs + + bl do_misaligned_access + + ; TBD: optimize - do this only if a callee reg was involved + ; either a dst of emulated LD/ST or src with address-writeback + RESTORE_CALLEE_SAVED_USER + + b ret_from_exception + +END(EV_TLBProtV) + +; Wrapper for Linux page fault handler called from EV_TLBMiss* +; Very similar to ProtV handler case (6a) above, but avoids the extra checks +; for Misaligned access +; +ENTRY(call_do_page_fault) + + EXCEPTION_PROLOGUE + lr r0, [efa] ; Faulting Data address + mov r1, sp + FAKE_RET_FROM_EXCPN + + mov blink, ret_from_exception + b do_page_fault + +END(call_do_page_fault) + +;############# Common Handlers for ARCompact and ARCv2 ############## + +#include "entry.S" + +;############# Return from Intr/Excp/Trap (ARC Specifics) ############## +; +; Restore the saved sys context (common exit-path for EXCPN/IRQ/Trap) +; IRQ shd definitely not happen between now and rtie +; All 2 entry points to here already disable interrupts + +.Lrestore_regs: + + # Interrupts are actually disabled from this point on, but will get + # reenabled after we return from interrupt/exception. + # But irq tracer needs to be told now... + TRACE_ASM_IRQ_ENABLE + + lr r10, [status32] + + ; Restore REG File. In case multiple Events outstanding, + ; use the same priority as rtie: EXCPN, L2 IRQ, L1 IRQ, None + ; Note that we use realtime STATUS32 (not pt_regs->status32) to + ; decide that. + + and.f 0, r10, (STATUS_A1_MASK|STATUS_A2_MASK) + bz .Lexcep_or_pure_K_ret + + ; Returning from Interrupts (Level 1 or 2) + +#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS + + ; Level 2 interrupt return Path - from hardware standpoint + bbit0 r10, STATUS_A2_BIT, not_level2_interrupt + + ;------------------------------------------------------------------ + ; However the context returning might not have taken L2 intr itself + ; e.g. Task'A' user-code -> L2 intr -> schedule -> 'B' user-code ret + ; Special considerations needed for the context which took L2 intr + + ld r9, [sp, PT_event] ; Ensure this is L2 intr context + brne r9, event_IRQ2, 149f + + ;------------------------------------------------------------------ + ; if L2 IRQ interrupted an L1 ISR, we'd disabled preemption earlier + ; so that sched doesn't move to new task, causing L1 to be delayed + ; undeterministically. Now that we've achieved that, let's reset + ; things to what they were, before returning from L2 context + ;---------------------------------------------------------------- + + ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs) + bbit0 r9, STATUS_A1_BIT, 149f ; L1 not active when L2 IRQ, so normal + + ; decrement thread_info->preempt_count (re-enable preemption) + GET_CURR_THR_INFO_FROM_SP r10 + ld r9, [r10, THREAD_INFO_PREEMPT_COUNT] + + ; paranoid check, given A1 was active when A2 happened, preempt count + ; must not be 0 because we would have incremented it. + ; If this does happen we simply HALT as it means a BUG !!! + cmp r9, 0 + bnz 2f + flag 1 + +2: + sub r9, r9, 1 + st r9, [r10, THREAD_INFO_PREEMPT_COUNT] + +149: + INTERRUPT_EPILOGUE 2 ; return from level 2 interrupt +debug_marker_l2: + rtie + +not_level2_interrupt: + +#endif + + INTERRUPT_EPILOGUE 1 ; return from level 1 interrupt +debug_marker_l1: + rtie + +.Lexcep_or_pure_K_ret: + + ;this case is for syscalls or Exceptions or pure kernel mode + + EXCEPTION_EPILOGUE +debug_marker_syscall: + rtie + +END(ret_from_exception) |