diff options
| author | Will Deacon <will.deacon@arm.com> | 2017-11-14 14:33:28 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-02-16 20:06:35 +0100 |
| commit | 0b5deee12ce7d0010838daf29c1c1a109af75715 (patch) | |
| tree | 9a9dc8c9da55b39c42d5199a149df74685d2b5c6 /arch/arm64/kernel | |
| parent | a5ed8761f80154414b4d259381d3997c9b6edb4f (diff) | |
arm64: tls: Avoid unconditional zeroing of tpidrro_el0 for native tasks
Commit 18011eac28c7 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/arm64/kernel')
| -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 */ |