[PATCH v4 2/2] arm64: enable context tracking
From: Christopher Covington <hidden>
Date: 2014-05-22 20:29:22
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Hi Larry, On 05/22/2014 03:27 PM, 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_and_irq). 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. Save/restore optimizations were also done by Kevin.
quoted hunk ↗ jump to hunk
--- 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, restore = 0 +#ifdef CONFIG_CONTEXT_TRACKING + bl context_tracking_user_exit + .if \restore == 1 + /* + * 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 ct_user_enter, save = 0 +#ifdef CONFIG_CONTEXT_TRACKING + .if \save == 1 + /* + * Save/restore only needed on syscall fastpath, which uses + * x0-x2. + */ + push x2, x3
Why is x3 saved?
+ push x0, x1 + .endif + bl context_tracking_user_enter + .if \save == 1 + pop x0, x1 + pop x2, x3 + .endif +#endif + .endm
Thanks, Christopher -- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation.