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arm64: don't restore GPRs when context tracking 

Now that syscalls are invoked with pt_regs, we no longer need to ensure
that the argument regsiters are live in the entry assembly, and it's
fine to not restore them after context_tracking_user_exit() has
corrupted them.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Mark Rutland 2018-07-11 14:56:46 +01:00 committed by Will Deacon
parent 3b7142752e
commit d9be03256d
1 changed files with 1 additions and 11 deletions
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12
arch/arm64/kernel/entry.S
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@ -41,19 +41,9 @@
* Context tracking subsystem. Used to instrument transitions
* between user and kernel mode.
*/
.macro ct_user_exit, syscall = 0
.macro ct_user_exit
#ifdef CONFIG_CONTEXT_TRACKING
bl context_tracking_user_exit
.if \syscall == 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