diff options
| author | Will Deacon <will.deacon@arm.com> | 2018-04-03 12:09:08 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-08 12:12:53 +0200 |
| commit | 6e7fb7cc6bc4053382477f64322251717d110d83 (patch) | |
| tree | 4e74e331f3fafcd06655763dd8db2d9743dea513 /arch | |
| parent | ded93ce56e9a96f94397699be447ba8e9e4b45c3 (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: Alex Shi <alex.shi@linaro.org> [v4.9 backport]
Signed-off-by: Mark Rutland <mark.rutland@arm.com> [v4.9 backport]
Tested-by: Will Deacon <will.deacon@arm.com>
Tested-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/kernel/process.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 0e7394915c70..0972ce58316d 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -306,17 +306,17 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start, static void tls_thread_switch(struct task_struct *next) { - unsigned long tpidr, tpidrro; + unsigned long tpidr; tpidr = read_sysreg(tpidr_el0); *task_user_tls(current) = tpidr; - 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 */ |