[PATCH] powerpc: Fix preserved memory size for int-vectors

[Christophe Leroy]

Le 09/01/2024 à 04:38, GUO Zihua a écrit :
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> 
> The first 32k of memory is reserved for interrupt vectors, however for
> powerpc64 this might not be enough. Fix this by reserving the maximum
> size between 32k and the real size of interrupt vectors.

You say "this might not be enough". Do you have exemples of when it is 
not enough, or is it just hypothetycal ?

> 
> Signed-off-by: GUO Zihua <guozihua at huawei.com>
> ---
>   arch/powerpc/kernel/prom.c | 11 ++++++++++-
>   1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
> index 0b5878c3125b..f374487513b3 100644
> --- a/arch/powerpc/kernel/prom.c
> +++ b/arch/powerpc/kernel/prom.c
> @@ -758,6 +758,7 @@ static inline void save_fscr_to_task(void) {}
>   void __init early_init_devtree(void *params)
>   {
>          phys_addr_t limit;
> +       size_t int_vector_size;

Why size_t ?

memblock_reserve() takes a phys_addr_t

> 
>          DBG(" -> early_init_devtree(%px)\n", params);
> 
> @@ -810,9 +811,17 @@ void __init early_init_devtree(void *params)
>          setup_initial_memory_limit(memstart_addr, first_memblock_size);
>          /* Reserve MEMBLOCK regions used by kernel, initrd, dt, etc... */
>          memblock_reserve(PHYSICAL_START, __pa(_end) - PHYSICAL_START);
> +#ifdef CONFIG_PPC64
> +       /* If relocatable, reserve at least 32k for interrupt vectors etc. */
> +       int_vector_size = (size_t)((uintptr_t)__end_interrupts -
> +                                  (uintptr_t)_stext);

Why do you need so many casts ? When I look into function 
overlaps_interrupt_vector_text() it seems to work well without cast at all.

> +       int_vector_size = max_t(size_t, 0x8000, int_vector_size);

Use SZ_32K instead of 0x8000

> +#else
>          /* If relocatable, reserve first 32k for interrupt vectors etc. */
> +       int_vector_size = 0x8000;

Use SZ_32K

> +#endif
>          if (PHYSICAL_START > MEMORY_START)
> -               memblock_reserve(MEMORY_START, 0x8000);
> +               memblock_reserve(MEMORY_START, int_vector_size);
>          reserve_kdump_trampoline();
>   #if defined(CONFIG_FA_DUMP) || defined(CONFIG_PRESERVE_FA_DUMP)
>          /*
> --
> 2.34.1
>