[PATCH v3 2/2] arm64: enable context tracking
From: Will Deacon <hidden>
Date: 2014-05-19 15:32:57
Also in:
lkml
On Fri, May 09, 2014 at 10:51:50PM +0100, Larry Bassel wrote:
Make calls to ct_user_enter when the kernel is exited and ct_user_exit when the kernel is entered (in el0_da, el0_ia, el0_svc, el0_irq and all of the "error" paths). These macros expand to function calls which will only work properly if el0_sync and related code has been rearranged (in a previous patch of this series). The calls to ct_user_exit are made after hw debugging has been enabled (enable_dbg). The call to ct_user_enter is made at the beginning of the kernel_exit macro. This patch is based on earlier work by Kevin Hilman.
[...]
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index 720e70b..301ea6a 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h@@ -108,6 +108,7 @@ static inline struct thread_info *current_thread_info(void) #define TIF_SINGLESTEP 21 #define TIF_32BIT 22 /* 32bit process */ #define TIF_SWITCH_MM 23 /* deferred switch_mm */ +#define TIF_NOHZ 24 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 136bb7d..c839bab 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S@@ -30,6 +30,44 @@ #include <asm/unistd32.h> /* + * Context tracking subsystem. Used to instrument transitions + * between user and kernel mode. + */ + .macro ct_user_exit, save = 0 +#ifdef CONFIG_CONTEXT_TRACKING + bl context_tracking_user_exit + .if \save == 1
It would be clearer to refer to the parameter as `restore' for the exit case, I reckon.
+ /* + * save/restore needed during syscalls. Restore syscall arguments from + * the values already saved on stack during kernel_entry + */ + ldp x0, x1, [sp] + ldp x2, x3, [sp, #S_X2] + ldp x4, x5, [sp, #S_X4] + ldp x6, x7, [sp, #S_X6] + .endif +#endif + .endm
[...]
.macro kernel_exit, el, ret = 0 ldp x21, x22, [sp, #S_PC] // load ELR, SPSR .if \el == 0 + ct_user_enter \ret ldr x23, [sp, #S_SP] // load return stack pointer .endif .if \ret
You should check how this patch applies against my debug exception rework:
2a2830703a23 ("arm64: debug: avoid accessing mdscr_el1 on fault paths where
possible") in today's next.
As well as addressing the conflicts, it's worth nothing that the thread_info
becomes available in tsk much earlier for exceptions from userspace with
that patch applied.
Will