Capture the protection key that got violated in paca.
This value will be later used to inform the signal
handler.

Signed-off-by: Ram Pai <linux...@us.ibm.com>
---
 arch/powerpc/include/asm/paca.h   |    1 +
 arch/powerpc/kernel/asm-offsets.c |    1 +
 arch/powerpc/mm/fault.c           |    8 ++++++++
 3 files changed, 10 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..6423277 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 */
@@ -453,6 +454,13 @@ 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();
+               /*
+                * The pgd-pdt...pmd-pte tree may not  have  been fully setup.
+                * Hence we cannot walk the tree to locate the pte, to locate
+                * the key. Hence  lets  call  vma_pkey() to get the key here
+                * instead of get_pte_pkey().
+                */
+               get_paca()->paca_pkey = vma_pkey(vma);
                code = SEGV_PKUERR;
                goto bad_area;
        }
-- 
1.7.1

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