From: Kevin Hilman Date: Thu, 28 Mar 2013 21:54:40 +0000 (+0100) Subject: ARM: 7688/1: add support for context tracking subsystem X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=b00884802043d9102ecc2abfdc37a7b35b30e52a;p=deliverable%2Flinux.git ARM: 7688/1: add support for context tracking subsystem commit 91d1aa43 (context_tracking: New context tracking susbsystem) generalized parts of the RCU userspace extended quiescent state into the context tracking subsystem. Context tracking is then used to implement adaptive tickless (a.k.a extended nohz) To support the new context tracking subsystem on ARM, the user/kernel boundary transtions need to be instrumented. For exceptions and IRQs in usermode, the existing usr_entry macro is used to instrument the user->kernel transition. For the return to usermode path, the ret_to_user* path is instrumented. Using the usr_entry macro, this covers interrupts in userspace, data abort and prefetch abort exceptions in userspace as well as undefined exceptions in userspace (which is where FP emulation and VFP are handled.) For syscalls, the slow return path is covered by instrumenting the ret_to_user path. In addition, the syscall entry point is instrumented which covers the user->kernel transition for both fast and slow syscalls, and an additional instrumentation point is added for the fast syscall return path (ret_fast_syscall). Cc: Mats Liljegren Cc: Frederic Weisbecker Signed-off-by: Kevin Hilman Signed-off-by: Russell King --- diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 5b714695b01b..7dc4cabc34d7 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -59,6 +59,7 @@ config ARM select CLONE_BACKWARDS select OLD_SIGSUSPEND3 select OLD_SIGACTION + select HAVE_CONTEXT_TRACKING help The ARM series is a line of low-power-consumption RISC chip designs licensed by ARM Ltd and targeted at embedded applications and diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h index cddda1f41f0f..1995d1a84060 100644 --- a/arch/arm/include/asm/thread_info.h +++ b/arch/arm/include/asm/thread_info.h @@ -152,6 +152,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *, #define TIF_SYSCALL_AUDIT 9 #define TIF_SYSCALL_TRACEPOINT 10 #define TIF_SECCOMP 11 /* seccomp syscall filtering active */ +#define TIF_NOHZ 12 /* in adaptive nohz mode */ #define TIF_USING_IWMMXT 17 #define TIF_MEMDIE 18 /* is terminating due to OOM killer */ #define TIF_RESTORE_SIGMASK 20 diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index 0f82098c9bfe..2b1de1b2f132 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -396,6 +396,7 @@ ENDPROC(__pabt_svc) #ifdef CONFIG_IRQSOFF_TRACER bl trace_hardirqs_off #endif + ct_user_exit save = 0 .endm .macro kuser_cmpxchg_check diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 3248cde504ed..469e82b3f757 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -41,6 +41,7 @@ ret_fast_syscall: /* 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 ) @@ -76,6 +77,7 @@ no_work_pending: #endif /* perform architecture specific actions before user return */ arch_ret_to_user r1, lr + ct_user_enter save = 0 restore_user_regs fast = 0, offset = 0 ENDPROC(ret_to_user_from_irq) @@ -394,6 +396,7 @@ ENTRY(vector_swi) mcr p15, 0, ip, c1, c0 @ update control register #endif enable_irq + ct_user_exit get_thread_info tsk adr tbl, sys_call_table @ load syscall table pointer diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index 9a8531eadd3d..782a94956286 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -163,6 +163,34 @@ .endm #endif /* !CONFIG_THUMB2_KERNEL */ +/* + * Context tracking subsystem. Used to instrument transitions + * between user and kernel mode. + */ + .macro ct_user_exit, save = 1 +#ifdef CONFIG_CONTEXT_TRACKING + .if \save + stmdb sp!, {r0-r3, ip, lr} + bl user_exit + ldmia sp!, {r0-r3, ip, lr} + .else + bl user_exit + .endif +#endif + .endm + + .macro ct_user_enter, save = 1 +#ifdef CONFIG_CONTEXT_TRACKING + .if \save + stmdb sp!, {r0-r3, ip, lr} + bl user_enter + ldmia sp!, {r0-r3, ip, lr} + .else + bl user_enter + .endif +#endif + .endm + /* * These are the registers used in the syscall handler, and allow us to * have in theory up to 7 arguments to a function - r0 to r6.