Le 04/11/2022 à 18:27, Andrew Donnellan a écrit :
> Enable CONFIG_VMAP_STACK for book3s64.
>
> To do this, we need to make some slight adjustments to set the stack SLB
> entry up for vmalloc rather than linear.
>
> For now, only enable if KVM_BOOK3S_64_HV is disabled (there's some real mode
> handlers we need to fix there).
There is one missing point : with VMAP_STACK, a stack overflow will
generate a page fault. You have to handle it at interrupt entry, before
going back to virtual mode, otherwise it will fault forever.
See how it is done in arch/powerpc/kernel/head_32.h, in macro
EXCEPTION_PROLOG_1
>
> Signed-off-by: Andrew Donnellan <a...@linux.ibm.com>
> ---
> arch/powerpc/kernel/process.c | 4 ++++
> arch/powerpc/mm/book3s64/slb.c | 11 +++++++++--
> arch/powerpc/platforms/Kconfig.cputype | 1 +
> 3 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 07917726c629..cadf2db5a2a8 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1685,7 +1685,11 @@ static void setup_ksp_vsid(struct task_struct *p,
> unsigned long sp)
> {
> #ifdef CONFIG_PPC_64S_HASH_MMU
> unsigned long sp_vsid;
> +#ifdef CONFIG_VMAP_STACK
> + unsigned long llp = mmu_psize_defs[mmu_vmalloc_psize].sllp;
> +#else /* CONFIG_VMAP_STACK */
> unsigned long llp = mmu_psize_defs[mmu_linear_psize].sllp;
> +#endif /* CONFIG_VMAP_STACK */
I think you could use IS_ENABLED() instead of an ifdef:
unsigned long llp;
if (IS_ENABLED(CONFIG_VMAP_STACK))
llp = mmu_psize_defs[mmu_vmalloc_psize].sllp;
else
llp = mmu_psize_defs[mmu_linear_psize].sllp;
>
> if (radix_enabled())
> return;
> diff --git a/arch/powerpc/mm/book3s64/slb.c b/arch/powerpc/mm/book3s64/slb.c
> index 6956f637a38c..0e21f0eaa7bb 100644
> --- a/arch/powerpc/mm/book3s64/slb.c
> +++ b/arch/powerpc/mm/book3s64/slb.c
> @@ -541,7 +541,7 @@ void slb_set_size(u16 size)
> void slb_initialize(void)
> {
> unsigned long linear_llp, vmalloc_llp, io_llp;
> - unsigned long lflags;
> + unsigned long lflags, kstack_flags;
> static int slb_encoding_inited;
> #ifdef CONFIG_SPARSEMEM_VMEMMAP
> unsigned long vmemmap_llp;
> @@ -582,11 +582,18 @@ void slb_initialize(void)
> * get_paca()->kstack hasn't been initialized yet.
> * For secondary cpus, we need to bolt the kernel stack entry now.
> */
> +
> +#ifdef CONFIG_VMAP_STACK
> + kstack_flags = SLB_VSID_KERNEL | vmalloc_llp;
> +#else
> + kstack_flags = SLB_VSID_KERNEL | linear_llp;
> +#endif
Same, should be
if (IS_ENABLED(CONFIG_VMAP_STACK))
kstack_flags = SLB_VSID_KERNEL | vmalloc_llp;
else
kstack_flags = SLB_VSID_KERNEL | linear_llp;
> slb_shadow_clear(KSTACK_INDEX);
> if (raw_smp_processor_id() != boot_cpuid &&
> (get_paca()->kstack & slb_esid_mask(mmu_kernel_ssize)) >
> PAGE_OFFSET)
> create_shadowed_slbe(get_paca()->kstack,
> - mmu_kernel_ssize, lflags, KSTACK_INDEX);
> + mmu_kernel_ssize, kstack_flags,
> + KSTACK_INDEX);
>
> asm volatile("isync":::"memory");
> }
> diff --git a/arch/powerpc/platforms/Kconfig.cputype
> b/arch/powerpc/platforms/Kconfig.cputype
> index 0c4eed9aea80..998317257797 100644
> --- a/arch/powerpc/platforms/Kconfig.cputype
> +++ b/arch/powerpc/platforms/Kconfig.cputype
> @@ -104,6 +104,7 @@ config PPC_BOOK3S_64
> select IRQ_WORK
> select PPC_64S_HASH_MMU if !PPC_RADIX_MMU
> select KASAN_VMALLOC if KASAN
> + select HAVE_ARCH_VMAP_STACK if KVM_BOOK3S_64_HV = n
Is it different from
select HAVE_ARCH_VMAP_STACK if !KVM_BOOK3S_64_HV ?
>
> config PPC_BOOK3E_64
> bool "Embedded processors"
