| Message ID | 20220127195712.748150-3-broonie@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64/mte: Asymmetric MTE support in userspace | expand |
On Thu, Jan 27, 2022 at 07:57:10PM +0000, Mark Brown wrote: > The code isn't that obscure but it probably won't hurt to have a little > bit more documentation for anyone trying to find out where everything > actually takes effect. > > Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
On 1/27/22 7:57 PM, Mark Brown wrote: > The code isn't that obscure but it probably won't hurt to have a little > bit more documentation for anyone trying to find out where everything > actually takes effect. > > Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> > --- > arch/arm64/kernel/mte.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c > index f418ebc65f95..fa4001fee12a 100644 > --- a/arch/arm64/kernel/mte.c > +++ b/arch/arm64/kernel/mte.c > @@ -186,6 +186,11 @@ void mte_check_tfsr_el1(void) > } > #endif > > +/* > + * This is where we actually resolve the system and process MTE mode > + * configuration into an actual value in SCTLR_EL1 that affects > + * userspace. > + */ > static void mte_update_sctlr_user(struct task_struct *task) > { > /* > @@ -199,8 +204,17 @@ static void mte_update_sctlr_user(struct task_struct *task) > unsigned long pref, resolved_mte_tcf; > > pref = __this_cpu_read(mte_tcf_preferred); > + /* > + * If there is no overlap between the system preferred and > + * program requested values go with what was requested. > + */ > resolved_mte_tcf = (mte_ctrl & pref) ? pref : mte_ctrl; > sctlr &= ~SCTLR_EL1_TCF0_MASK; > + /* > + * Pick an actual setting. The order in which we check for > + * set bits and map into register values determines our > + * default order. > + */ > if (resolved_mte_tcf & MTE_CTRL_TCF_ASYNC) > sctlr |= SCTLR_EL1_TCF0_ASYNC; > else if (resolved_mte_tcf & MTE_CTRL_TCF_SYNC) >
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index f418ebc65f95..fa4001fee12a 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -186,6 +186,11 @@ void mte_check_tfsr_el1(void) } #endif +/* + * This is where we actually resolve the system and process MTE mode + * configuration into an actual value in SCTLR_EL1 that affects + * userspace. + */ static void mte_update_sctlr_user(struct task_struct *task) { /* @@ -199,8 +204,17 @@ static void mte_update_sctlr_user(struct task_struct *task) unsigned long pref, resolved_mte_tcf; pref = __this_cpu_read(mte_tcf_preferred); + /* + * If there is no overlap between the system preferred and + * program requested values go with what was requested. + */ resolved_mte_tcf = (mte_ctrl & pref) ? pref : mte_ctrl; sctlr &= ~SCTLR_EL1_TCF0_MASK; + /* + * Pick an actual setting. The order in which we check for + * set bits and map into register values determines our + * default order. + */ if (resolved_mte_tcf & MTE_CTRL_TCF_ASYNC) sctlr |= SCTLR_EL1_TCF0_ASYNC; else if (resolved_mte_tcf & MTE_CTRL_TCF_SYNC)
The code isn't that obscure but it probably won't hurt to have a little bit more documentation for anyone trying to find out where everything actually takes effect. Signed-off-by: Mark Brown <broonie@kernel.org> --- arch/arm64/kernel/mte.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)