From 4d1c2ee2709fd6e1655206cafcdb22737f5d7379 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Mon, 2 Aug 2021 15:07:32 +0100 Subject: arm64: entry: move bulk of ret_to_user to C In `ret_to_user` we perform some conditional work depending on the thread flags, then perform some IRQ/context tracking which is intended to balance with the IRQ/context tracking performed in the entry C code. For simplicity and consistency, it would be preferable to move this all to C. As a step towards that, this patch moves the conditional work and IRQ/context tracking into a C helper function. To aid bisectability, this is called from the `ret_to_user` assembly, and a subsequent patch will move the call to C code. As local_daif_mask() handles all necessary tracing and PMR manipulation, we no longer need to handle this explicitly. As we call exit_to_user_mode() directly, the `user_enter_irqoff` macro is no longer used, and can be removed. As enter_from_user_mode() and exit_to_user_mode() are no longer called from assembly, these can be made static, and as these are typically very small, they are marked __always_inline to avoid the overhead of a function call. For now, enablement of single-step is left in entry.S, and for this we still need to read the flags in ret_to_user(). It is safe to read this separately as TIF_SINGLESTEP is not part of _TIF_WORK_MASK. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland Cc: James Morse Cc: Joey Gouly Cc: Marc Zyngier Cc: Will Deacon Reviewed-by: Joey Gouly Link: https://lore.kernel.org/r/20210802140733.52716-4-mark.rutland@arm.com [catalin.marinas@arm.com: removed unused gic_prio_kentry_setup macro] Signed-off-by: Catalin Marinas --- arch/arm64/kernel/entry.S | 48 +++-------------------------------------------- 1 file changed, 3 insertions(+), 45 deletions(-) (limited to 'arch/arm64/kernel/entry.S') diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 863d44f73028..b59eee28cc1b 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -29,16 +29,6 @@ #include #include -/* - * Context tracking and irqflag tracing need to instrument transitions between - * user and kernel mode. - */ - .macro user_enter_irqoff -#if defined(CONFIG_CONTEXT_TRACKING) || defined(CONFIG_TRACE_IRQFLAGS) - bl exit_to_user_mode -#endif - .endm - .macro clear_gp_regs .irp n,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29 mov x\n, xzr @@ -474,18 +464,6 @@ SYM_CODE_END(__swpan_exit_el0) /* GPRs used by entry code */ tsk .req x28 // current thread_info -/* - * Interrupt handling. - */ - .macro gic_prio_kentry_setup, tmp:req -#ifdef CONFIG_ARM64_PSEUDO_NMI - alternative_if ARM64_HAS_IRQ_PRIO_MASKING - mov \tmp, #(GIC_PRIO_PSR_I_SET | GIC_PRIO_IRQON) - msr_s SYS_ICC_PMR_EL1, \tmp - alternative_else_nop_endif -#endif - .endm - .text /* @@ -585,37 +563,17 @@ SYM_CODE_START_LOCAL(ret_to_kernel) kernel_exit 1 SYM_CODE_END(ret_to_kernel) -/* - * "slow" syscall return path. - */ SYM_CODE_START_LOCAL(ret_to_user) - disable_daif - gic_prio_kentry_setup tmp=x3 -#ifdef CONFIG_TRACE_IRQFLAGS - bl trace_hardirqs_off -#endif - ldr x19, [tsk, #TSK_TI_FLAGS] - and x2, x19, #_TIF_WORK_MASK - cbnz x2, work_pending -finish_ret_to_user: - user_enter_irqoff + mov x0, sp + bl asm_exit_to_user_mode /* Ignore asynchronous tag check faults in the uaccess routines */ clear_mte_async_tcf + ldr x19, [tsk, #TSK_TI_FLAGS] // re-check for single-step enable_step_tsk x19, x2 #ifdef CONFIG_GCC_PLUGIN_STACKLEAK bl stackleak_erase #endif kernel_exit 0 - -/* - * Ok, we need to do extra processing, enter the slow path. - */ -work_pending: - mov x0, sp // 'regs' - mov x1, x19 - bl do_notify_resume - ldr x19, [tsk, #TSK_TI_FLAGS] // re-check for single-step - b finish_ret_to_user SYM_CODE_END(ret_to_user) .popsection // .entry.text -- cgit