powerpc: Refactor verification of MSR_RI

40x and BOOKE don't have MSR_RI therefore all tests involving
MSR_RI may be problematic on those plateforms.

Create helpers to check or set MSR_RI in regs, and use them
in common code.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c2fb93708196734f4176dda334aaa3055f213b89.1629707037.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/ptrace.h

@@ -22,6 +22,7 @@
 #include <linux/err.h>
 #include <uapi/asm/ptrace.h>
 #include <asm/asm-const.h>
+#include <asm/reg.h>
 
 #ifndef __ASSEMBLY__
 struct pt_regs
@@ -272,6 +273,28 @@ static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
 	regs->gpr[3] = rc;
 }
 
+static inline bool cpu_has_msr_ri(void)
+{
+	return !IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x);
+}
+
+static inline bool regs_is_unrecoverable(struct pt_regs *regs)
+{
+	return unlikely(cpu_has_msr_ri() && !(regs->msr & MSR_RI));
+}
+
+static inline void regs_set_recoverable(struct pt_regs *regs)
+{
+	if (cpu_has_msr_ri())
+		regs_set_return_msr(regs, regs->msr | MSR_RI);
+}
+
+static inline void regs_set_unrecoverable(struct pt_regs *regs)
+{
+	if (cpu_has_msr_ri())
+		regs_set_return_msr(regs, regs->msr & ~MSR_RI);
+}
+
 #define arch_has_single_step()	(1)
 #define arch_has_block_step()	(true)
 #define ARCH_HAS_USER_SINGLE_STEP_REPORT

arch/powerpc/kernel/interrupt.c

@@ -92,8 +92,7 @@ notrace long system_call_exception(long r3, long r4, long r5,
 	CT_WARN_ON(ct_state() == CONTEXT_KERNEL);
 	user_exit_irqoff();
 
-	if (!IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x))
+	BUG_ON(regs_is_unrecoverable(regs));
-		BUG_ON(!(regs->msr & MSR_RI));
 	BUG_ON(!(regs->msr & MSR_PR));
 	BUG_ON(arch_irq_disabled_regs(regs));
 
@@ -462,8 +461,7 @@ notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs)
 {
 	unsigned long ret;
 
-	if (!IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x))
+	BUG_ON(regs_is_unrecoverable(regs));
-		BUG_ON(!(regs->msr & MSR_RI));
 	BUG_ON(arch_irq_disabled_regs(regs));
 	CT_WARN_ON(ct_state() == CONTEXT_USER);
 
@@ -494,8 +492,7 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs)
 	bool stack_store = current_thread_info()->flags &
 						_TIF_EMULATE_STACK_STORE;
 
-	if (!IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x) &&
+	if (regs_is_unrecoverable(regs))
-	    unlikely(!(regs->msr & MSR_RI)))
 		unrecoverable_exception(regs);
 	/*
 	 * CT_WARN_ON comes here via program_check_exception,

arch/powerpc/kernel/traps.c

@@ -428,7 +428,7 @@ void hv_nmi_check_nonrecoverable(struct pt_regs *regs)
 	return;
 
 nonrecoverable:
-	regs_set_return_msr(regs, regs->msr & ~MSR_RI);
+	regs_set_unrecoverable(regs);
 #endif
 }
 DEFINE_INTERRUPT_HANDLER_NMI(system_reset_exception)
@@ -498,7 +498,7 @@ out:
 		die("Unrecoverable nested System Reset", regs, SIGABRT);
 #endif
 	/* Must die if the interrupt is not recoverable */
-	if (!(regs->msr & MSR_RI)) {
+	if (regs_is_unrecoverable(regs)) {
 		/* For the reason explained in die_mce, nmi_exit before die */
 		nmi_exit();
 		die("Unrecoverable System Reset", regs, SIGABRT);
@@ -550,7 +550,7 @@ static inline int check_io_access(struct pt_regs *regs)
 			printk(KERN_DEBUG "%s bad port %lx at %p\n",
 			       (*nip & 0x100)? "OUT to": "IN from",
 			       regs->gpr[rb] - _IO_BASE, nip);
-			regs_set_return_msr(regs, regs->msr | MSR_RI);
+			regs_set_recoverable(regs);
 			regs_set_return_ip(regs, extable_fixup(entry));
 			return 1;
 		}
@@ -840,7 +840,7 @@ DEFINE_INTERRUPT_HANDLER_NMI(machine_check_exception)
 
 bail:
 	/* Must die if the interrupt is not recoverable */
-	if (!(regs->msr & MSR_RI))
+	if (regs_is_unrecoverable(regs))
 		die_mce("Unrecoverable Machine check", regs, SIGBUS);
 
 #ifdef CONFIG_PPC_BOOK3S_64

arch/powerpc/mm/book3s64/slb.c

@@ -822,7 +822,7 @@ DEFINE_INTERRUPT_HANDLER_RAW(do_slb_fault)
 	/* IRQs are not reconciled here, so can't check irqs_disabled */
 	VM_WARN_ON(mfmsr() & MSR_EE);
 
-	if (unlikely(!(regs->msr & MSR_RI)))
+	if (regs_is_unrecoverable(regs))
 		return -EINVAL;
 
 	/*

arch/powerpc/platforms/embedded6xx/holly.c

@@ -251,7 +251,7 @@ static int ppc750_machine_check_exception(struct pt_regs *regs)
 	/* Are we prepared to handle this fault */
 	if ((entry = search_exception_tables(regs->nip)) != NULL) {
 		tsi108_clear_pci_cfg_error();
-		regs_set_return_msr(regs, regs->msr | MSR_RI);
+		regs_set_recoverable(regs);
 		regs_set_return_ip(regs, extable_fixup(entry));
 		return 1;
 	}

arch/powerpc/platforms/embedded6xx/mpc7448_hpc2.c

@@ -173,7 +173,7 @@ static int mpc7448_machine_check_exception(struct pt_regs *regs)
 	/* Are we prepared to handle this fault */
 	if ((entry = search_exception_tables(regs->nip)) != NULL) {
 		tsi108_clear_pci_cfg_error();
-		regs_set_return_msr(regs, regs->msr | MSR_RI);
+		regs_set_recoverable(regs);
 		regs_set_return_ip(regs, extable_fixup(entry));
 		return 1;
 	}

arch/powerpc/platforms/pasemi/idle.c

@@ -58,7 +58,7 @@ static int pasemi_system_reset_exception(struct pt_regs *regs)
 	restore_astate(hard_smp_processor_id());
 
 	/* everything handled */
-	regs_set_return_msr(regs, regs->msr | MSR_RI);
+	regs_set_recoverable(regs);
 	return 1;
 }
 

arch/powerpc/platforms/powernv/opal.c

@@ -588,7 +588,7 @@ static int opal_recover_mce(struct pt_regs *regs,
 {
 	int recovered = 0;
 
-	if (!(regs->msr & MSR_RI)) {
+	if (regs_is_unrecoverable(regs)) {
 		/* If MSR_RI isn't set, we cannot recover */
 		pr_err("Machine check interrupt unrecoverable: MSR(RI=0)\n");
 		recovered = 0;

arch/powerpc/platforms/pseries/ras.c

@@ -783,7 +783,7 @@ static int recover_mce(struct pt_regs *regs, struct machine_check_event *evt)
 {
 	int recovered = 0;
 
-	if (!(regs->msr & MSR_RI)) {
+	if (regs_is_unrecoverable(regs)) {
 		/* If MSR_RI isn't set, we cannot recover */
 		pr_err("Machine check interrupt unrecoverable: MSR(RI=0)\n");
 		recovered = 0;

arch/powerpc/sysdev/fsl_rio.c

@@ -108,7 +108,7 @@ int fsl_rio_mcheck_exception(struct pt_regs *regs)
 				 __func__);
 			out_be32((u32 *)(rio_regs_win + RIO_LTLEDCSR),
 				 0);
-			regs_set_return_msr(regs, regs->msr | MSR_RI);
+			regs_set_recoverable(regs);
 			regs_set_return_ip(regs, extable_fixup(entry));
 			return 1;
 		}

arch/powerpc/xmon/xmon.c

@@ -482,16 +482,6 @@ static inline void get_output_lock(void) {}
 static inline void release_output_lock(void) {}
 #endif
 
-static inline int unrecoverable_excp(struct pt_regs *regs)
-{
-#if defined(CONFIG_4xx) || defined(CONFIG_PPC_BOOK3E)
-	/* We have no MSR_RI bit on 4xx or Book3e, so we simply return false */
-	return 0;
-#else
-	return ((regs->msr & MSR_RI) == 0);
-#endif
-}
-
 static void xmon_touch_watchdogs(void)
 {
 	touch_softlockup_watchdog_sync();
@@ -565,7 +555,7 @@ static int xmon_core(struct pt_regs *regs, volatile int fromipi)
 	bp = NULL;
 	if ((regs->msr & (MSR_IR|MSR_PR|MSR_64BIT)) == (MSR_IR|MSR_64BIT))
 		bp = at_breakpoint(regs->nip);
-	if (bp || unrecoverable_excp(regs))
+	if (bp || regs_is_unrecoverable(regs))
 		fromipi = 0;
 
 	if (!fromipi) {
@@ -577,7 +567,7 @@ static int xmon_core(struct pt_regs *regs, volatile int fromipi)
 			       cpu, BP_NUM(bp));
 			xmon_print_symbol(regs->nip, " ", ")\n");
 		}
-		if (unrecoverable_excp(regs))
+		if (regs_is_unrecoverable(regs))
 			printf("WARNING: exception is not recoverable, "
 			       "can't continue\n");
 		release_output_lock();
@@ -693,7 +683,7 @@ static int xmon_core(struct pt_regs *regs, volatile int fromipi)
 			printf("Stopped at breakpoint %tx (", BP_NUM(bp));
 			xmon_print_symbol(regs->nip, " ", ")\n");
 		}
-		if (unrecoverable_excp(regs))
+		if (regs_is_unrecoverable(regs))
 			printf("WARNING: exception is not recoverable, "
 			       "can't continue\n");
 		remove_bpts();