diff options
| author | Will Deacon <will.deacon@arm.com> | 2017-11-14 14:33:28 +0000 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2017-12-11 13:41:03 +0000 |
| commit | 18011eac28c7cb31c87b86b7d0e5b01894405c7f (patch) | |
| tree | efa4a258adc6d272214883d12316cfa34002b9dc /arch/arm64/kernel/process.c | |
| parent | d1777e686ad10ba7c594304429c6045fb79255a1 (diff) | |
arm64: tls: Avoid unconditional zeroing of tpidrro_el0 for native tasks
When unmapping the kernel at EL0, we use tpidrro_el0 as a scratch register
during exception entry from native tasks and subsequently zero it in
the kernel_ventry macro. We can therefore avoid zeroing tpidrro_el0
in the context-switch path for native tasks using the entry trampoline.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel/process.c')
| -rw-r--r-- | arch/arm64/kernel/process.c | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 6b7dcf4310ac..583fd8154695 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -370,16 +370,14 @@ void tls_preserve_current_state(void) static void tls_thread_switch(struct task_struct *next) { - unsigned long tpidr, tpidrro; - tls_preserve_current_state(); - tpidr = *task_user_tls(next); - tpidrro = is_compat_thread(task_thread_info(next)) ? - next->thread.tp_value : 0; + if (is_compat_thread(task_thread_info(next))) + write_sysreg(next->thread.tp_value, tpidrro_el0); + else if (!arm64_kernel_unmapped_at_el0()) + write_sysreg(0, tpidrro_el0); - write_sysreg(tpidr, tpidr_el0); - write_sysreg(tpidrro, tpidrro_el0); + write_sysreg(*task_user_tls(next), tpidr_el0); } /* Restore the UAO state depending on next's addr_limit */ |