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Subject[RFC v6 34/62] powerpc: capture the violated protection key on fault
Date
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 <linuxram@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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