[RFC v7 21/25] powerpc: capture AMR register content on pkey violation

[Ram Pai]

capture AMR register contents, and save it in paca
whenever a pkey violation is detected.

This value will be needed to deliver pkey-violation
signal to the task.

Signed-off-by: Ram Pai <linuxram at us.ibm.com>
---
 arch/powerpc/include/asm/paca.h   |    3 +++
 arch/powerpc/kernel/asm-offsets.c |    5 +++++
 arch/powerpc/mm/fault.c           |    2 ++
 3 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 1c09f8f..c8bd1fc 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -92,6 +92,9 @@ struct paca_struct {
 	struct dtl_entry *dispatch_log_end;
 #endif /* CONFIG_PPC_STD_MMU_64 */
 	u64 dscr_default;		/* per-CPU default DSCR */
+#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+	u64 paca_amr;			/* value of amr at exception */
+#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 709e234..17f5d8a 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -241,6 +241,11 @@ int main(void)
 	OFFSET(PACAHWCPUID, paca_struct, hw_cpu_id);
 	OFFSET(PACAKEXECSTATE, paca_struct, kexec_state);
 	OFFSET(PACA_DSCR_DEFAULT, paca_struct, dscr_default);
+
+#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+	OFFSET(PACA_AMR, paca_struct, paca_amr);
+#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
+
 	OFFSET(ACCOUNT_STARTTIME, paca_struct, accounting.starttime);
 	OFFSET(ACCOUNT_STARTTIME_USER, paca_struct, accounting.starttime_user);
 	OFFSET(ACCOUNT_USER_TIME, paca_struct, accounting.utime);
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index ea74fe2..a6710f5 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -264,6 +264,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 #ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
 	if (error_code & DSISR_KEYFAULT) {
 		code = SEGV_PKUERR;
+		get_paca()->paca_amr = read_amr();
 		goto bad_area_nosemaphore;
 	}
 #endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
@@ -451,6 +452,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 #ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
 	if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
 			is_exec, 0)) {
+		get_paca()->paca_amr = read_amr();
 		code = SEGV_PKUERR;
 		goto bad_area;
 	}
-- 
1.7.1