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| author | Mark Rutland <mark.rutland@arm.com> | 2020-11-30 12:59:44 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-11-30 13:11:37 +0100 |
| commit | 3cb5ed4d76c15fb97c10e5e9f5268d92c68222ca (patch) | |
| tree | 8508227f2d219c60dd00f6c9f52cbc3cdf869821 /arch/arm64/kernel/irq.c | |
| parent | arm64: entry: move enter_from_user_mode to entry-common.c (diff) | |
| download | linux-3cb5ed4d76c15fb97c10e5e9f5268d92c68222ca.tar.xz linux-3cb5ed4d76c15fb97c10e5e9f5268d92c68222ca.zip | |
arm64: entry: prepare ret_to_user for function call
In a subsequent patch ret_to_user will need to make a C function call
(in some configurations) which may clobber x0-x18 at the start of the
finish_ret_to_user block, before enable_step_tsk consumes the flags
loaded into x1.
In preparation for this, let's load the flags into x19, which is
preserved across C function calls. This avoids a redundant reload of the
flags and ensures we operate on a consistent shapshot regardless.
There should be no functional change as a result of this patch. At this
point of the entry/exit paths we only need to preserve x28 (tsk) and the
sp, and x19 is free for this use.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201130115950.22492-6-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel/irq.c')
0 files changed, 0 insertions, 0 deletions