On 07/06/2017 02:52 AM, Ram Pai wrote:
> Capture the protection key that got violated in paca.
> This value will be used by used to inform the signal
> handler.
>
> Signed-off-by: Ram Pai <linuxram@xxxxxxxxxx>
> ---
> arch/powerpc/include/asm/paca.h | 1 +
> arch/powerpc/kernel/asm-offsets.c | 1 +
> arch/powerpc/mm/fault.c | 3 +++
> 3 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
> index c8bd1fc..0c06188 100644
> --- a/arch/powerpc/include/asm/paca.h
> +++ b/arch/powerpc/include/asm/paca.h
> @@ -94,6 +94,7 @@ struct paca_struct {
> u64 dscr_default; /* per-CPU default DSCR */
> #ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
> u64 paca_amr; /* value of amr at exception */
> + u16 paca_pkey; /* exception causing pkey */
> #endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
>
> #ifdef CONFIG_PPC_STD_MMU_64
> diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
> index 17f5d8a..7dff862 100644
> --- a/arch/powerpc/kernel/asm-offsets.c
> +++ b/arch/powerpc/kernel/asm-offsets.c
> @@ -244,6 +244,7 @@ int main(void)
>
> #ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
> OFFSET(PACA_AMR, paca_struct, paca_amr);
> + OFFSET(PACA_PKEY, paca_struct, paca_pkey);
> #endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
>
> OFFSET(ACCOUNT_STARTTIME, paca_struct, accounting.starttime);
> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
> index a6710f5..c8674a7 100644
> --- a/arch/powerpc/mm/fault.c
> +++ b/arch/powerpc/mm/fault.c
> @@ -265,6 +265,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
> if (error_code & DSISR_KEYFAULT) {
> code = SEGV_PKUERR;
> get_paca()->paca_amr = read_amr();
> + get_paca()->paca_pkey = get_pte_pkey(current->mm, address);
> goto bad_area_nosemaphore;
> }
> #endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
> @@ -290,6 +291,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
>
> perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
>
> +
Stray empty line addition here.
> /*
> * We want to do this outside mmap_sem, because reading code around nip
> * can result in fault, which will cause a deadlock when called with
> @@ -453,6 +455,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
> if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
> is_exec, 0)) {
> get_paca()->paca_amr = read_amr();
> + get_paca()->paca_pkey = vma_pkey(vma);
Why not get_pte_pkey() here as well ? IIUC both these function would
give us the same pkey, then why is the difference when we process a
page fault for real protection key violation in HW compared to cross
checking of VMA protection key in SW for regular page faults.
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