diff options
Diffstat (limited to 'kernel/arch/arm/kernel/entry-common.S')
| -rw-r--r-- | kernel/arch/arm/kernel/entry-common.S | 75 |
1 files changed, 56 insertions, 19 deletions
diff --git a/kernel/arch/arm/kernel/entry-common.S b/kernel/arch/arm/kernel/entry-common.S index 4e7f40c57..c3bd6cbfc 100644 --- a/kernel/arch/arm/kernel/entry-common.S +++ b/kernel/arch/arm/kernel/entry-common.S @@ -24,35 +24,60 @@ .align 5 +#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING)) /* - * This is the fast syscall return path. We do as little as - * possible here, and this includes saving r0 back into the SVC - * stack. + * This is the fast syscall return path. We do as little as possible here, + * such as avoiding writing r0 to the stack. We only use this path if we + * have tracing and context tracking disabled - the overheads from those + * features make this path too inefficient. */ ret_fast_syscall: UNWIND(.fnstart ) UNWIND(.cantunwind ) - disable_irq @ disable interrupts + disable_irq_notrace @ disable interrupts ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing - tst r1, #_TIF_SYSCALL_WORK - bne __sys_trace_return - tst r1, #_TIF_WORK_MASK + tst r1, #((_TIF_SYSCALL_WORK | _TIF_WORK_MASK) & ~_TIF_SECCOMP) + bne fast_work_pending + tst r1, #_TIF_SECCOMP bne fast_work_pending - asm_trace_hardirqs_on /* perform architecture specific actions before user return */ arch_ret_to_user r1, lr - ct_user_enter restore_user_regs fast = 1, offset = S_OFF UNWIND(.fnend ) +ENDPROC(ret_fast_syscall) -/* - * Ok, we need to do extra processing, enter the slow path. - */ + /* Ok, we need to do extra processing, enter the slow path. */ fast_work_pending: str r0, [sp, #S_R0+S_OFF]! @ returned r0 -work_pending: + /* fall through to work_pending */ +#else +/* + * The "replacement" ret_fast_syscall for when tracing or context tracking + * is enabled. As we will need to call out to some C functions, we save + * r0 first to avoid needing to save registers around each C function call. + */ +ret_fast_syscall: + UNWIND(.fnstart ) + UNWIND(.cantunwind ) + str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 + disable_irq_notrace @ disable interrupts + ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing + tst r1, #((_TIF_SYSCALL_WORK | _TIF_WORK_MASK) & ~_TIF_SECCOMP) + bne do_slower_path + tst r1, #_TIF_SECCOMP + beq no_work_pending +do_slower_path: + UNWIND(.fnend ) +ENDPROC(ret_fast_syscall) + + /* Slower path - fall through to work_pending */ +#endif + + tst r1, #_TIF_SYSCALL_WORK + bne __sys_trace_return_nosave +slow_work_pending: mov r0, sp @ 'regs' mov r2, why @ 'syscall' bl do_work_pending @@ -61,19 +86,23 @@ work_pending: movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) ldmia sp, {r0 - r6} @ have to reload r0 - r6 b local_restart @ ... and off we go +ENDPROC(ret_fast_syscall) /* * "slow" syscall return path. "why" tells us if this was a real syscall. + * IRQs may be enabled here, so always disable them. Note that we use the + * "notrace" version to avoid calling into the tracing code unnecessarily. + * do_work_pending() will update this state if necessary. */ ENTRY(ret_to_user) ret_slow_syscall: - disable_irq @ disable interrupts + disable_irq_notrace @ disable interrupts ENTRY(ret_to_user_from_irq) ldr r1, [tsk, #TI_FLAGS] tst r1, #_TIF_WORK_MASK - bne work_pending + bne slow_work_pending no_work_pending: - asm_trace_hardirqs_on + asm_trace_hardirqs_on save = 0 /* perform architecture specific actions before user return */ arch_ret_to_user r1, lr @@ -90,7 +119,7 @@ ENTRY(ret_from_fork) bl schedule_tail cmp r5, #0 movne r0, r4 - adrne lr, BSYM(1f) + badrne lr, 1f retne r5 1: get_thread_info tsk b ret_slow_syscall @@ -173,6 +202,8 @@ ENTRY(vector_swi) USER( ldr scno, [lr, #-4] ) @ get SWI instruction #endif + uaccess_disable tbl + adr tbl, sys_call_table @ load syscall table pointer #if defined(CONFIG_OABI_COMPAT) @@ -198,7 +229,7 @@ local_restart: bne __sys_trace cmp scno, #NR_syscalls @ check upper syscall limit - adr lr, BSYM(ret_fast_syscall) @ return address + badr lr, ret_fast_syscall @ return address ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine add r1, sp, #S_OFF @@ -233,7 +264,7 @@ __sys_trace: add r0, sp, #S_OFF bl syscall_trace_enter - adr lr, BSYM(__sys_trace_return) @ return address + badr lr, __sys_trace_return @ return address mov scno, r0 @ syscall number (possibly new) add r1, sp, #S_R0 + S_OFF @ pointer to regs cmp scno, #NR_syscalls @ check upper syscall limit @@ -251,6 +282,12 @@ __sys_trace_return: bl syscall_trace_exit b ret_slow_syscall +__sys_trace_return_nosave: + enable_irq_notrace + mov r0, sp + bl syscall_trace_exit + b ret_slow_syscall + .align 5 #ifdef CONFIG_ALIGNMENT_TRAP .type __cr_alignment, #object |