From c505b0da76a67139e073a5a5c4a1986b1cf168d3 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Tue, 19 May 2020 16:01:52 -0700 Subject: ARC: entry: rework (non-functional) - comments update - rename syscall_trace_entry - use PT_xxx in entry code Signed-off-by: Vineet Gupta --- arch/arc/include/asm/entry-arcv2.h | 23 ++++++++++-------- arch/arc/include/asm/entry-compact.h | 3 ++- arch/arc/include/asm/ptrace.h | 2 +- arch/arc/kernel/asm-offsets.c | 1 + arch/arc/kernel/entry.S | 45 ++++++++++++++++-------------------- arch/arc/kernel/ptrace.c | 2 +- 6 files changed, 39 insertions(+), 37 deletions(-) (limited to 'arch/arc') diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h index 858742feab71..a38ed505b3de 100644 --- a/arch/arc/include/asm/entry-arcv2.h +++ b/arch/arc/include/asm/entry-arcv2.h @@ -48,14 +48,18 @@ /*------------------------------------------------------------------------*/ .macro INTERRUPT_PROLOGUE - ; (A) Before jumping to Interrupt Vector, hardware micro-ops did following: + ; Before jumping to Interrupt Vector, hardware micro-ops did following: ; 1. SP auto-switched to kernel mode stack ; 2. STATUS32.Z flag set if in U mode at time of interrupt (U:1,K:0) ; 3. Auto save: (mandatory) Push PC and STAT32 on stack ; hardware does even if CONFIG_ARC_IRQ_NO_AUTOSAVE - ; 4. Auto save: (optional) r0-r11, blink, LPE,LPS,LPC, JLI,LDI,EI + ; 4a. Auto save: (optional) r0-r11, blink, LPE,LPS,LPC, JLI,LDI,EI ; - ; (B) Manually saved some regs: r12,r30, sp,fp,gp, ACCL pair + ; Now + ; 4b. If Auto-save (optional) not enabled in hw, manually save them + ; 5. Manually save: r12,r30, sp,fp,gp, ACCL pair + ; + ; At the end, SP points to pt_regs #ifdef CONFIG_ARC_IRQ_NO_AUTOSAVE ; carve pt_regs on stack (case #3), PC/STAT32 already on stack @@ -73,13 +77,14 @@ /*------------------------------------------------------------------------*/ .macro EXCEPTION_PROLOGUE - ; (A) Before jumping to Exception Vector, hardware micro-ops did following: + ; Before jumping to Exception Vector, hardware micro-ops did following: ; 1. SP auto-switched to kernel mode stack ; 2. STATUS32.Z flag set if in U mode at time of exception (U:1,K:0) ; - ; (B) Manually save the complete reg file below + ; Now manually save rest of reg file + ; At the end, SP points to pt_regs - sub sp, sp, SZ_PT_REGS ; carve pt_regs + sub sp, sp, SZ_PT_REGS ; carve space for pt_regs ; _HARD saves r10 clobbered by _SOFT as scratch hence comes first @@ -136,8 +141,8 @@ ST2 gp, fp, PT_r26 ; gp (r26), fp (r27) - st r12, [sp, PT_sp + 4] - st r30, [sp, PT_sp + 8] + st r12, [sp, PT_r12] + st r30, [sp, PT_r30] ; Saving pt_regs->sp correctly requires some extra work due to the way ; Auto stack switch works @@ -244,7 +249,7 @@ btst r0, STATUS_U_BIT ; Z flag set if K, used in restoring SP - ld r10, [sp, PT_event + 4] + ld r10, [sp, PT_bta] sr r10, [erbta] LD2 r10, r11, PT_ret diff --git a/arch/arc/include/asm/entry-compact.h b/arch/arc/include/asm/entry-compact.h index e3383e1cb040..4e2ae82779ed 100644 --- a/arch/arc/include/asm/entry-compact.h +++ b/arch/arc/include/asm/entry-compact.h @@ -170,12 +170,13 @@ PUSHAX erbta lr r10, [ecr] - st r10, [sp, PT_event] /* EV_Trap expects r10 to have ECR */ + st r10, [sp, PT_event] #ifdef CONFIG_ARC_CURR_IN_REG /* gp already saved on stack: now load with "current" */ GET_CURR_TASK_ON_CPU gp #endif + ; OUTPUT: r10 has ECR expected by EV_Trap .endm /*-------------------------------------------------------------- diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h index e9798f46cdc4..2bf8ea96ea21 100644 --- a/arch/arc/include/asm/ptrace.h +++ b/arch/arc/include/asm/ptrace.h @@ -75,7 +75,7 @@ struct pt_regs { unsigned long event; }; - unsigned long bta; /* bta_l1, bta_l2, erbta */ + unsigned long bta; /* erbta */ unsigned long r26; /* gp */ unsigned long fp; diff --git a/arch/arc/kernel/asm-offsets.c b/arch/arc/kernel/asm-offsets.c index 5b47d09b925e..e46688975868 100644 --- a/arch/arc/kernel/asm-offsets.c +++ b/arch/arc/kernel/asm-offsets.c @@ -47,6 +47,7 @@ int main(void) DEFINE(PT_status32, offsetof(struct pt_regs, status32)); DEFINE(PT_event, offsetof(struct pt_regs, event)); + DEFINE(PT_bta, offsetof(struct pt_regs, bta)); DEFINE(PT_sp, offsetof(struct pt_regs, sp)); DEFINE(PT_r0, offsetof(struct pt_regs, r0)); DEFINE(PT_r1, offsetof(struct pt_regs, r1)); diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S index cd26e0fa5044..f291fc8476d7 100644 --- a/arch/arc/kernel/entry.S +++ b/arch/arc/kernel/entry.S @@ -160,20 +160,19 @@ END(EV_Extension) ; syscall Tracing ; --------------------------------------------- tracesys: - ; save EFA in case tracer wants the PC of traced task - ; using ERET won't work since next-PC has already committed + ; safekeep EFA (r12) if syscall tracer wanted PC + ; for traps, ERET is pre-commit so points to next-PC GET_CURR_TASK_FIELD_PTR TASK_THREAD, r11 st r12, [r11, THREAD_FAULT_ADDR] ; thread.fault_address - ; PRE Sys Call Ptrace hook - mov r0, sp ; pt_regs needed - bl @syscall_trace_entry + ; PRE syscall trace hook + mov r0, sp ; pt_regs + bl @syscall_trace_enter ; Tracing code now returns the syscall num (orig or modif) mov r8, r0 ; Do the Sys Call as we normally would. - ; Validate the Sys Call number cmp r8, NR_syscalls - 1 mov.hi r0, -ENOSYS bhi tracesys_exit @@ -190,36 +189,36 @@ tracesys: ld r6, [sp, PT_r6] ld r7, [sp, PT_r7] ld.as r9, [sys_call_table, r8] - jl [r9] ; Entry into Sys Call Handler + jl [r9] tracesys_exit: - st r0, [sp, PT_r0] ; sys call return value in pt_regs + st r0, [sp, PT_r0] - ;POST Sys Call Ptrace Hook + ; POST syscall trace hook mov r0, sp ; pt_regs needed bl @syscall_trace_exit - b ret_from_exception ; NOT ret_from_system_call at is saves r0 which - ; we'd done before calling post hook above + + ; don't call ret_from_system_call as it saves r0, already done above + b ret_from_exception ; --------------------------------------------- ; Breakpoint TRAP ; --------------------------------------------- trap_with_param: mov r0, r12 ; EFA in case ptracer/gdb wants stop_pc - mov r1, sp + mov r1, sp ; pt_regs - ; Save callee regs in case gdb wants to have a look - ; SP will grow up by size of CALLEE Reg-File + ; save callee regs in case tracer/gdb wants to peek SAVE_CALLEE_SAVED_USER - ; save location of saved Callee Regs @ thread_struct->pc + ; safekeep ref to callee regs GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 st sp, [r10, THREAD_CALLEE_REG] - ; Call the trap handler + ; call the non syscall trap handler bl do_non_swi_trap - ; unwind stack to discard Callee saved Regs + ; unwind stack to discard callee regs DISCARD_CALLEE_SAVED_USER b ret_from_exception @@ -237,31 +236,27 @@ ENTRY(EV_Trap) FAKE_RET_FROM_EXCPN - ;============ TRAP 1 :breakpoints - ; Check ECR for trap with arg (PROLOGUE ensures r10 has ECR) + ;============ TRAP N : breakpoints, kprobes etc bmsk.f 0, r10, 7 bnz trap_with_param - ;============ TRAP (no param): syscall top level + ;============ TRAP 0 (no param): syscall - ; If syscall tracing ongoing, invoke pre-post-hooks + ; syscall tracing ongoing, invoke pre-post-hooks around syscall GET_CURR_THR_INFO_FLAGS r10 and.f 0, r10, _TIF_SYSCALL_WORK bnz tracesys ; this never comes back ;============ Normal syscall case - ; syscall num shd not exceed the total system calls avail cmp r8, NR_syscalls - 1 mov.hi r0, -ENOSYS bhi .Lret_from_system_call - ; Offset into the syscall_table and call handler ld.as r9,[sys_call_table, r8] - jl [r9] ; Entry into Sys Call Handler + jl [r9] .Lret_from_system_call: - st r0, [sp, PT_r0] ; sys call return value in pt_regs ; fall through to ret_from_exception diff --git a/arch/arc/kernel/ptrace.c b/arch/arc/kernel/ptrace.c index 8226df3163fe..14ea7406f5cd 100644 --- a/arch/arc/kernel/ptrace.c +++ b/arch/arc/kernel/ptrace.c @@ -339,7 +339,7 @@ long arch_ptrace(struct task_struct *child, long request, return ret; } -asmlinkage int syscall_trace_entry(struct pt_regs *regs) +asmlinkage int syscall_trace_enter(struct pt_regs *regs) { if (test_thread_flag(TIF_SYSCALL_TRACE)) if (ptrace_report_syscall_entry(regs)) -- cgit