[PATCHv2] ARM: OMAP2+: Fix regression for smc calls for vmap stack

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. For omap_secure_dispatcher(), we need
to use a cpu specific buffer as there's nothing currently ensuring it only
gets called from cpu0.

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 | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

On Thu, 31 Mar 2022 at 19:17, Tony Lindgren <tony@atomide.com> wrote:
>
> 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. For omap_secure_dispatcher(), we need
> to use a cpu specific buffer as there's nothing currently ensuring it only
> gets called from cpu0.
>
> 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>

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>

> ---
>  arch/arm/mach-omap2/omap-secure.c | 13 ++++++++++---
>  1 file changed, 10 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 +59,13 @@ 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 buf[NR_CPUS][5];
> +       u32 *param;
> +       int cpu;
>         u32 ret;
> -       u32 param[5];
> +
> +       cpu = get_cpu();
> +       param = buf[cpu];
>
>         param[0] = nargs;
>         param[1] = arg1;
> @@ -76,6 +81,8 @@ u32 omap_secure_dispatcher(u32 idx, u32 flag, u32 nargs, u32 arg1, u32 arg2,
>         outer_clean_range(__pa(param), __pa(param + 5));
>         ret = omap_smc2(idx, flag, __pa(param));
>
> +       put_cpu();
> +
>         return ret;
>  }
>
> @@ -119,8 +126,8 @@ 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 +160,8 @@ 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