[PATCH] ARM: OMAP2+: Fix regression for smc calls for vmap stack

[PATCH] ARM: OMAP2+: Fix regression for smc calls for vmap stack

[Tony Lindgren]

Commit 9c46929e7989 ("ARM: implement THREAD_INFO_IN_TASK for uniprocessor
systems") started triggering an issue with smc calls hanging on boot as
VMAP_STACK is now enabled by default.

Based on discussions on the #armlinux irc channel, Arnd noticed that omaps
are using __pa() for stack for smc calls. This does not work with vmap
stack.

Let's fix the issue by changing the param arrays to use static param[5] for
each function for __pa() to work. This consumes a bit more memory compared
to adding a single static buffer, but avoids potential races with the smc
calls initializing the shared buffer.

Fixes: 9c46929e7989 ("ARM: implement THREAD_INFO_IN_TASK for uniprocessor systems")
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tony Lindgren <tony@atomide.com>
---
 arch/arm/mach-omap2/omap-secure.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mach-omap2/omap-secure.c b/arch/arm/mach-omap2/omap-secure.c
--- a/arch/arm/mach-omap2/omap-secure.c
+++ b/arch/arm/mach-omap2/omap-secure.c
@@ -59,8 +59,8 @@ static void __init omap_optee_init_check(void)
 u32 omap_secure_dispatcher(u32 idx, u32 flag, u32 nargs, u32 arg1, u32 arg2,
 							 u32 arg3, u32 arg4)
 {
+	static u32 param[5];
 	u32 ret;
-	u32 param[5];
 
 	param[0] = nargs;
 	param[1] = arg1;
@@ -119,8 +119,8 @@ phys_addr_t omap_secure_ram_mempool_base(void)
 #if defined(CONFIG_ARCH_OMAP3) && defined(CONFIG_PM)
 u32 omap3_save_secure_ram(void __iomem *addr, int size)
 {
+	static u32 param[5];
 	u32 ret;
-	u32 param[5];
 
 	if (size != OMAP3_SAVE_SECURE_RAM_SZ)
 		return OMAP3_SAVE_SECURE_RAM_SZ;
@@ -153,8 +153,8 @@ u32 omap3_save_secure_ram(void __iomem *addr, int size)
 u32 rx51_secure_dispatcher(u32 idx, u32 process, u32 flag, u32 nargs,
 			   u32 arg1, u32 arg2, u32 arg3, u32 arg4)
 {
+	static u32 param[5];
 	u32 ret;
-	u32 param[5];
 
 	param[0] = nargs+1; /* RX-51 needs number of arguments + 1 */
 	param[1] = arg1;
-- 
2.35.1

Re: [PATCH] ARM: OMAP2+: Fix regression for smc calls for vmap stack

[Arnd Bergmann]

On Thu, Mar 31, 2022 at 4:42 PM Tony Lindgren <tony@atomide.com> wrote:
> diff --git a/arch/arm/mach-omap2/omap-secure.c b/arch/arm/mach-omap2/omap-secure.c
> --- a/arch/arm/mach-omap2/omap-secure.c
> +++ b/arch/arm/mach-omap2/omap-secure.c
> @@ -59,8 +59,8 @@ static void __init omap_optee_init_check(void)
>  u32 omap_secure_dispatcher(u32 idx, u32 flag, u32 nargs, u32 arg1, u32 arg2,
>                                                          u32 arg3, u32 arg4)
>  {
> +       static u32 param[5];
>         u32 ret;
> -       u32 param[5];

I think for this one, you do need to use a DEFINE_PER_CPU() to make it
work when multiple cores run into the function concurrently. This is entered
on OMAP44xx from irq_notifier() with cmd==CPU_CLUSTER_PM_ENTER
and from start_secondary(). I suspect that one can show these never happen
on more than one CPU at a time, but I have not been able to prove that
myself.

> @@ -119,8 +119,8 @@ phys_addr_t omap_secure_ram_mempool_base(void)
>  #if defined(CONFIG_ARCH_OMAP3) && defined(CONFIG_PM)
>  u32 omap3_save_secure_ram(void __iomem *addr, int size)
>  {
> +       static u32 param[5];
>         u32 ret;
> -       u32 param[5];
>
>         if (size != OMAP3_SAVE_SECURE_RAM_SZ)
>                 return OMAP3_SAVE_SECURE_RAM_SZ;
> @@ -153,8 +153,8 @@ u32 omap3_save_secure_ram(void __iomem *addr, int size)
>  u32 rx51_secure_dispatcher(u32 idx, u32 process, u32 flag, u32 nargs,
>                            u32 arg1, u32 arg2, u32 arg3, u32 arg4)
>  {
> +       static u32 param[5];
>         u32 ret;
> -       u32 param[5];
>
>         param[0] = nargs+1; /* RX-51 needs number of arguments + 1 */
>         param[1] = arg1;

These look good, as they are clearly only run on single-core SoCs
with preemption disabled.

         Arnd

Re: [PATCH] ARM: OMAP2+: Fix regression for smc calls for vmap stack

[Tony Lindgren]

* Arnd Bergmann <arnd@arndb.de> [220331 15:25]:
> On Thu, Mar 31, 2022 at 4:42 PM Tony Lindgren <tony@atomide.com> wrote:
> > diff --git a/arch/arm/mach-omap2/omap-secure.c b/arch/arm/mach-omap2/omap-secure.c
> > --- a/arch/arm/mach-omap2/omap-secure.c
> > +++ b/arch/arm/mach-omap2/omap-secure.c
> > @@ -59,8 +59,8 @@ static void __init omap_optee_init_check(void)
> >  u32 omap_secure_dispatcher(u32 idx, u32 flag, u32 nargs, u32 arg1, u32 arg2,
> >                                                          u32 arg3, u32 arg4)
> >  {
> > +       static u32 param[5];
> >         u32 ret;
> > -       u32 param[5];
> 
> I think for this one, you do need to use a DEFINE_PER_CPU() to make it
> work when multiple cores run into the function concurrently. This is entered
> on OMAP44xx from irq_notifier() with cmd==CPU_CLUSTER_PM_ENTER
> and from start_secondary(). I suspect that one can show these never happen
> on more than one CPU at a time, but I have not been able to prove that
> myself.

Yeah makes sense. Will post v2.

Regards,

Tony