Commit b0088480 authored by Kevin Hilman's avatar Kevin Hilman Committed by Russell King
Browse files

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 <mats.liljegren@enea.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarKevin Hilman <khilman@linaro.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 4fd75911
......@@ -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
......
......@@ -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
......
......@@ -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
......
......@@ -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
......
......@@ -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.
......
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