powerpc/rtas: various cleanups and improvements

Disable MSR[EE] in C code rather than asm.

Signed-off-by Nicholas Piggin <[email protected]>

---
 arch/powerpc/kernel/rtas.c       |  4 ++++
 arch/powerpc/kernel/rtas_entry.S | 17 +----------------
 2 files changed, 5 insertions(+), 16 deletions(-)

arch/powerpc/kernel/rtas.c +4 -0

index 733e6ef36758..6b5892d6a56b 100644
@@ -49,6 +49,10 @@ void enter_rtas(unsigned long);
 
 static inline void do_enter_rtas(unsigned long args)
 {
+	BUG_ON(!irqs_disabled());
+
+	hard_irq_disable(); /* Ensure MSR[EE] is disabled on PPC64 */
+
 	enter_rtas(args);
 
 	srr_regs_clobbered(); /* rtas uses SRRs, invalidate */

arch/powerpc/kernel/rtas_entry.S +1 -16

index 6fa10eb49a9c..45fa661c2ff6 100644
@@ -24,8 +24,6 @@ _GLOBAL(enter_rtas)
 	lwz	r4,RTASBASE(r4)
 	mfmsr	r9
 	stw	r9,8(r1)
-	LOAD_REG_IMMEDIATE(r0,MSR_KERNEL)
-	mtmsr	r0	/* disable interrupts so SRR0/1 don't get trashed */
 	li	r9,MSR_KERNEL & ~(MSR_IR|MSR_DR)
 	mtlr	r6
 	stw	r1, THREAD + RTAS_SP(r2)

@@ -87,20 +85,7 @@ _GLOBAL(enter_rtas)
 	li	r0,0
 	mtcr	r0
 
-#ifdef CONFIG_BUG
-	/* There is no way it is acceptable to get here with interrupts enabled,
-	 * check it with the asm equivalent of WARN_ON
-	 */
-	lbz	r0,PACAIRQSOFTMASK(r13)
-1:	tdeqi	r0,IRQS_ENABLED
-	EMIT_WARN_ENTRY 1b,__FILE__,__LINE__,BUGFLAG_WARNING
-#endif
-
-	/* Hard-disable interrupts */
 	mfmsr	r6
-	rldicl	r7,r6,48,1
-	rotldi	r7,r7,16
-	mtmsrd	r7,1
 
 	/* Unfortunately, the stack pointer and the MSR are also clobbered,
 	 * so they are saved in the PACA which allows us to restore

@@ -124,7 +109,7 @@ _GLOBAL(enter_rtas)
 	andc	r6,r0,r9
 
 __enter_rtas:
-	sync				/* disable interrupts so SRR0/1 */
+	sync				/* disable RI so SRR0/1 */
 	mtmsrd	r0			/* don't get trashed */
 
 	LOAD_REG_ADDR(r4, rtas)

mtmsrd L=1 can clear MSR[RI] without the previous MSR value; it does not require sync; it can be moved later to before SRRs are live.

Signed-off-by Nicholas Piggin <[email protected]>

---
 arch/powerpc/kernel/rtas_entry.S | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

arch/powerpc/kernel/rtas_entry.S +3 -3

index 45fa661c2ff6..7b93687b9a10 100644
@@ -109,13 +109,13 @@ _GLOBAL(enter_rtas)
 	andc	r6,r0,r9
 
 __enter_rtas:
-	sync				/* disable RI so SRR0/1 */
-	mtmsrd	r0			/* don't get trashed */
-
 	LOAD_REG_ADDR(r4, rtas)
 	ld	r5,RTASENTRY(r4)	/* get the rtas->entry value */
 	ld	r4,RTASBASE(r4)		/* get the rtas->base value */
 
+	li	r0,0
+	mtmsrd	r0,1			/* disable RI before using SRR0/1 */
+
 	mtspr	SPRN_SRR0,r5
 	mtspr	SPRN_SRR1,r6
 	RFI_TO_KERNEL

Rather than adjust the current MSR value to find the rtas entry MSR on 64-bit, load the explicit value we want as 32-bit does.

This prevents some facilities (e.g., VEC and VSX) from being left enabled which doesn't seem to cause a problem but it's more consistent to always use the same MSR and minimise facilities enabled.

Signed-off-by Nicholas Piggin <[email protected]>

---
 arch/powerpc/kernel/rtas_entry.S | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

arch/powerpc/kernel/rtas_entry.S +1 -8

index 7b93687b9a10..08eb731f08b8 100644
@@ -99,14 +99,7 @@ _GLOBAL(enter_rtas)
 	clrldi	r4,r4,2			/* convert to realmode address */
 	mtlr	r4
 
-	li	r0,0
-	ori	r0,r0,MSR_EE|MSR_SE|MSR_BE|MSR_RI
-	andc	r0,r6,r0
-
-	li	r9,1
-	rldicr	r9,r9,MSR_SF_LG,(63-MSR_SF_LG)
-	ori	r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP|MSR_RI|MSR_LE
-	andc	r6,r0,r9
+	LOAD_REG_IMMEDIATE(r6, MSR_ME)
 
 __enter_rtas:
 	LOAD_REG_ADDR(r4, rtas)

On 64-bit, PACA is saved in a SPRG so it does not need to be saved on stack. We also don't need to mask off the top bits for real mode addresses because the architecture does this for us.

Signed-off-by Nicholas Piggin <[email protected]>

---
 arch/powerpc/kernel/rtas_entry.S | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

arch/powerpc/kernel/rtas_entry.S +4 -9

index 08eb731f08b8..5f65ea4436c6 100644
@@ -62,10 +62,9 @@ _GLOBAL(enter_rtas)
 
 	/* Because RTAS is running in 32b mode, it clobbers the high order half
 	 * of all registers that it saves.  We therefore save those registers
-	 * RTAS might touch to the stack.  (r0, r3-r13 are caller saved)
+	 * RTAS might touch to the stack.  (r0, r3-r12 are caller saved)
 	 */
 	SAVE_GPR(2, r1)			/* Save the TOC */
-	SAVE_GPR(13, r1)		/* Save paca */
 	SAVE_NVGPRS(r1)			/* Save the non-volatiles */
 
 	mfcr	r4

@@ -129,15 +128,14 @@ rtas_return_loc:
 	mtmsrd	r6
 
 	/* relocation is off at this point */
-	GET_PACA(r4)
-	clrldi	r4,r4,2			/* convert to realmode address */
+	GET_PACA(r13)
 
 	bcl	20,31,$+4
 0:	mflr	r3
 	ld	r3,(1f-0b)(r3)		/* get &rtas_restore_regs */
 
-	ld	r1,PACAR1(r4)		/* Restore our SP */
-	ld	r4,PACASAVEDMSR(r4)	/* Restore our MSR */
+	ld	r1,PACAR1(r13)		/* Restore our SP */
+	ld	r4,PACASAVEDMSR(r13)	/* Restore our MSR */
 
 	mtspr	SPRN_SRR0,r3
 	mtspr	SPRN_SRR1,r4

@@ -153,11 +151,8 @@ _ASM_NOKPROBE_SYMBOL(rtas_return_loc)
 rtas_restore_regs:
 	/* relocation is on at this point */
 	REST_GPR(2, r1)			/* Restore the TOC */
-	REST_GPR(13, r1)		/* Restore paca */
 	REST_NVGPRS(r1)			/* Restore the non-volatiles */
 
-	GET_PACA(r13)
-
 	ld	r4,_CCR(r1)
 	mtcr	r4
 	ld	r5,_CTR(r1)

This moves MSR save/restore and some real-mode juggling out of asm and into C code, simplifying things.

Signed-off-by Nicholas Piggin <[email protected]>

---
 arch/powerpc/kernel/rtas.c       | 15 ++++++++++++---
 arch/powerpc/kernel/rtas_entry.S | 32 +++++---------------------------
 2 files changed, 17 insertions(+), 30 deletions(-)

arch/powerpc/kernel/rtas.c +12 -3

index 6b5892d6a56b..87ede1877816 100644
@@ -47,13 +47,22 @@
 /* This is here deliberately so it's only used in this file */
 void enter_rtas(unsigned long);
 
-static inline void do_enter_rtas(unsigned long args)
+static noinline void do_enter_rtas(unsigned long args)
 {
 	BUG_ON(!irqs_disabled());
 
-	hard_irq_disable(); /* Ensure MSR[EE] is disabled on PPC64 */
+	if (IS_ENABLED(CONFIG_PPC64)) {
+		unsigned long msr;
 
-	enter_rtas(args);
+		hard_irq_disable();
+
+		msr = mfmsr();
+		mtmsr(msr & ~(MSR_IR|MSR_DR));
+		enter_rtas(args);
+		mtmsr(msr);
+	} else {
+		enter_rtas(args);
+	}
 
 	srr_regs_clobbered(); /* rtas uses SRRs, invalidate */
 }

arch/powerpc/kernel/rtas_entry.S +4 -7

index 5f65ea4436c6..292551684bbd 100644
@@ -84,14 +84,11 @@ _GLOBAL(enter_rtas)
 	li	r0,0
 	mtcr	r0
 
-	mfmsr	r6
-
-	/* Unfortunately, the stack pointer and the MSR are also clobbered,
-	 * so they are saved in the PACA which allows us to restore
-	 * our original state after RTAS returns.
+	/*
+	 * The stack pointer is clobbered, so it is saved in the PACA which
+	 * allows us to restore our original state after RTAS returns.
 	 */
 	std	r1,PACAR1(r13)
-	std	r6,PACASAVEDMSR(r13)
 
 	/* Setup our real return addr */
 	LOAD_REG_ADDR(r4,rtas_return_loc)

@@ -100,7 +97,6 @@ _GLOBAL(enter_rtas)
 
 	LOAD_REG_IMMEDIATE(r6, MSR_ME)
 
-__enter_rtas:
 	LOAD_REG_ADDR(r4, rtas)
 	ld	r5,RTASENTRY(r4)	/* get the rtas->entry value */
 	ld	r4,RTASBASE(r4)		/* get the rtas->base value */

@@ -112,6 +108,7 @@ __enter_rtas:
 	mtspr	SPRN_SRR1,r6
 	RFI_TO_KERNEL
 	b	.	/* prevent speculative execution */
+_ASM_NOKPROBE_SYMBOL(enter_rtas)
 
 rtas_return_loc:
 	FIXUP_ENDIAN

arch/powerpc/kernel/rtas_entry.S +0 -1

-	/* relocation is off at this point */
 	GET_PACA(r13)
 

arch/powerpc/kernel/rtas_entry.S +1 -11

-	b	.	/* prevent speculative execution */
-_ASM_NOKPROBE_SYMBOL(enter_rtas)
-_ASM_NOKPROBE_SYMBOL(__enter_rtas)
-_ASM_NOKPROBE_SYMBOL(rtas_return_loc)
-
-	.align	3
-1:	.8byte	rtas_restore_regs
-
-rtas_restore_regs:
-	/* relocation is on at this point */
 	REST_GPR(2, r1)			/* Restore the TOC */
 	REST_NVGPRS(r1)			/* Restore the non-volatiles */
 

@@ -169,5 +147,5 @@ rtas_restore_regs:
 
 	mtlr	r0
 	blr				/* return to caller */
-
+_ASM_NOKPROBE_SYMBOL(rtas_return_loc)
 #endif /* CONFIG_PPC32 */

This moves MSR save/restore and some real-mode juggling out of asm and into C code, simplifying things.

Signed-off-by Nicholas Piggin <[email protected]>

---
 arch/powerpc/kernel/rtas.c       | 15 ++++++++++++---
 arch/powerpc/kernel/rtas_entry.S | 32 +++++---------------------------
 2 files changed, 17 insertions(+), 30 deletions(-)

arch/powerpc/kernel/rtas.c +1 -1

index 6b5892d6a56b..87ede1877816 100644
@@ -47,13 +47,22 @@
 /* This is here deliberately so it's only used in this file */
 void enter_rtas(unsigned long);
 
-static inline void do_enter_rtas(unsigned long args)
+static noinline void do_enter_rtas(unsigned long args)
 {
 	BUG_ON(!irqs_disabled());

arch/powerpc/kernel/rtas.c +5 -0

+		enter_rtas(args);
+		mtmsr(msr);
+	} else {
+		enter_rtas(args);
+	}
 
 	srr_regs_clobbered(); /* rtas uses SRRs, invalidate */
 }

arch/powerpc/kernel/rtas_entry.S +3 -7

index 5f65ea4436c6..292551684bbd 100644
@@ -84,14 +84,11 @@ _GLOBAL(enter_rtas)
 	li	r0,0
 	mtcr	r0
 
-	mfmsr	r6
-
-	/* Unfortunately, the stack pointer and the MSR are also clobbered,
-	 * so they are saved in the PACA which allows us to restore
-	 * our original state after RTAS returns.
+	/*
+	 * The stack pointer is clobbered, so it is saved in the PACA which
+	 * allows us to restore our original state after RTAS returns.
 	 */
 	std	r1,PACAR1(r13)
-	std	r6,PACASAVEDMSR(r13)
 
 	/* Setup our real return addr */
 	LOAD_REG_ADDR(r4,rtas_return_loc)

@@ -100,7 +97,6 @@ _GLOBAL(enter_rtas)
 
 	LOAD_REG_IMMEDIATE(r6, MSR_ME)
 
-__enter_rtas:
 	LOAD_REG_ADDR(r4, rtas)
 	ld	r5,RTASENTRY(r4)	/* get the rtas->entry value */
 	ld	r4,RTASBASE(r4)		/* get the rtas->base value */

arch/powerpc/kernel/rtas_entry.S +1 -1

 	b	.	/* prevent speculative execution */
+_ASM_NOKPROBE_SYMBOL(enter_rtas)
 
 rtas_return_loc:
 	FIXUP_ENDIAN

@@ -127,29 +124,10 @@ rtas_return_loc:
 	sync
 	mtmsrd	r6
 
-	/* relocation is off at this point */>  	GET_PACA(r13)
 

arch/powerpc/kernel/rtas_entry.S +1 -11

-	b	.	/* prevent speculative execution */
-_ASM_NOKPROBE_SYMBOL(enter_rtas)
-_ASM_NOKPROBE_SYMBOL(__enter_rtas)
-_ASM_NOKPROBE_SYMBOL(rtas_return_loc)
-
-	.align	3
-1:	.8byte	rtas_restore_regs
-
-rtas_restore_regs:
-	/* relocation is on at this point */
 	REST_GPR(2, r1)			/* Restore the TOC */
 	REST_NVGPRS(r1)			/* Restore the non-volatiles */
 

@@ -169,5 +147,5 @@ rtas_restore_regs:
 
 	mtlr	r0
 	blr				/* return to caller */
-
+_ASM_NOKPROBE_SYMBOL(rtas_return_loc)
 #endif /* CONFIG_PPC32 */

PAPR specifies that RTAS may be called with MSR[RI] enabled if the calling context is recoverable, and RTAS will manage RI as necessary. Call the rtas entry point with RI enabled, and add a check to ensure the caller has RI enabled.

Signed-off-by Nicholas Piggin <[email protected]>

---
 arch/powerpc/kernel/rtas.c       |  1 +
 arch/powerpc/kernel/rtas_entry.S | 13 +++----------
 2 files changed, 4 insertions(+), 10 deletions(-)

arch/powerpc/kernel/rtas.c +1 -0

index 87ede1877816..fece066115f0 100644
@@ -57,6 +57,7 @@ static noinline void do_enter_rtas(unsigned long args)
 		hard_irq_disable();
 
 		msr = mfmsr();
+		BUG_ON(!(msr & MSR_RI));
 		mtmsr(msr & ~(MSR_IR|MSR_DR));
 		enter_rtas(args);
 		mtmsr(msr);

arch/powerpc/kernel/rtas_entry.S +1 -2

index 292551684bbd..72b27b14ccc9 100644
@@ -95,7 +95,7 @@ _GLOBAL(enter_rtas)
 	clrldi	r4,r4,2			/* convert to realmode address */
 	mtlr	r4
 
-	LOAD_REG_IMMEDIATE(r6, MSR_ME)
+	LOAD_REG_IMMEDIATE(r6, MSR_ME|MSR_RI)
 
 	LOAD_REG_ADDR(r4, rtas)
 	ld	r5,RTASENTRY(r4)	/* get the rtas->entry value */

@@ -113,15 +113,8 @@ _ASM_NOKPROBE_SYMBOL(enter_rtas)
 rtas_return_loc:
 	FIXUP_ENDIAN
 
-	/*

arch/powerpc/kernel/rtas_entry.S +0 -0

 	mtmsrd	r6
 
 	GET_PACA(r13)

Use the same calling and rets return convention with the raw rtas call rather than requiring callers to load and byteswap return values out of rtas_args.

Signed-off-by Nicholas Piggin <[email protected]>

---
 arch/powerpc/include/asm/rtas.h              |  4 +-
 arch/powerpc/kernel/rtas.c                   | 53 +++++++++++---------
 arch/powerpc/platforms/pseries/hotplug-cpu.c |  2 +-
 arch/powerpc/platforms/pseries/ras.c         |  7 +--
 arch/powerpc/xmon/xmon.c                     |  2 +-
 5 files changed, 33 insertions(+), 35 deletions(-)

arch/powerpc/include/asm/rtas.h +0 -0

index 82e5b055fa2a..1014ff140cf8 100644

arch/powerpc/include/asm/rtas.h +0 -0

 extern void __noreturn rtas_restart(char *cmd);
 extern void rtas_power_off(void);
 extern void __noreturn rtas_halt(void);

arch/powerpc/kernel/rtas.c +28 -25

index fece066115f0..751a20669669 100644
@@ -123,7 +123,7 @@ static void call_rtas_display_status(unsigned char c)
 		return;
 
 	s = lock_rtas();
-	rtas_call_unlocked(&rtas.args, 10, 1, 1, NULL, c);
+	raw_rtas_call(&rtas.args, 10, 1, 1, NULL, c);
 	unlock_rtas(s);
 }
 

@@ -434,10 +434,9 @@ static char *__fetch_rtas_last_error(char *altbuf)
 #define get_errorlog_buffer()		NULL
 #endif
 
-
-static void
-va_rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret,
-		      va_list list)
+static int notrace va_raw_rtas_call(struct rtas_args *args, int token,
+				int nargs, int nret, int *outputs,
+				va_list list)
 {
 	int i;
 

@@ -453,21 +452,37 @@ va_rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret,
 		args->rets[i] = 0;
 
 	do_enter_rtas(__pa(args));
+
+	if (nret > 1 && outputs != NULL) {
+		for (i = 0; i < nret-1; ++i)
+			outputs[i] = be32_to_cpu(args->rets[i+1]);
+	}
+
+	return (nret > 0) ? be32_to_cpu(args->rets[0]) : 0;
 }
 
-void rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret, ...)
+/*
+ * Like rtas_call but no kmalloc or printk etc in error handling, so
+ * error won't go through log_error. No tracing, may be called in real mode.
+ * rtas_args must be supplied, and appropriate synchronization for the rtas
+ * call being made has to be performed by the caller.
+ */
+int notrace raw_rtas_call(struct rtas_args *args, int token,
+			int nargs, int nret, int *outputs, ...)
 {
 	va_list list;
+	int ret;
 
-	va_start(list, nret);
-	va_rtas_call_unlocked(args, token, nargs, nret, list);
+	va_start(list, outputs);
+	ret = va_raw_rtas_call(args, token, nargs, nret, outputs, list);
 	va_end(list);
+
+	return ret;
 }
 
 int rtas_call(int token, int nargs, int nret, int *outputs, ...)
 {
 	va_list list;
-	int i;
 	unsigned long s;
 	struct rtas_args *rtas_args;
 	char *buff_copy = NULL;

@@ -482,19 +497,14 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...)
 	rtas_args = &rtas.args;
 
 	va_start(list, outputs);
-	va_rtas_call_unlocked(rtas_args, token, nargs, nret, list);
+	ret = va_raw_rtas_call(rtas_args, token, nargs, nret, outputs, list);
 	va_end(list);
 
 	/* A -1 return code indicates that the last command couldn't
 	   be completed due to a hardware error. */
-	if (be32_to_cpu(rtas_args->rets[0]) == -1)
+	if (ret == -1)
 		buff_copy = __fetch_rtas_last_error(NULL);
 
-	if (nret > 1 && outputs != NULL)
-		for (i = 0; i < nret-1; ++i)
-			outputs[i] = be32_to_cpu(rtas_args->rets[i+1]);
-	ret = (nret > 0)? be32_to_cpu(rtas_args->rets[0]): 0;
-
 	unlock_rtas(s);
 
 	if (buff_copy) {

@@ -950,7 +960,7 @@ int rtas_call_reentrant(int token, int nargs, int nret, int *outputs, ...)
 	va_list list;
 	struct rtas_args *args;
 	unsigned long flags;
-	int i, ret = 0;
+	int ret;
 
 	if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
 		return -1;

@@ -962,16 +972,9 @@ int rtas_call_reentrant(int token, int nargs, int nret, int *outputs, ...)
 	args = local_paca->rtas_args_reentrant;
 
 	va_start(list, outputs);
-	va_rtas_call_unlocked(args, token, nargs, nret, list);
+	ret = va_raw_rtas_call(args, token, nargs, nret, outputs, list);
 	va_end(list);
 
-	if (nret > 1 && outputs)
-		for (i = 0; i < nret - 1; ++i)
-			outputs[i] = be32_to_cpu(args->rets[i + 1]);
-
-	if (nret > 0)
-		ret = be32_to_cpu(args->rets[0]);
-
 	local_irq_restore(flags);
 	preempt_enable();
 

arch/powerpc/platforms/pseries/hotplug-cpu.c +1 -1

index b81fc846d99c..17c05650b6b9 100644
@@ -53,7 +53,7 @@ static void rtas_stop_self(void)
 
 	BUG_ON(rtas_stop_self_token == RTAS_UNKNOWN_SERVICE);
 
-	rtas_call_unlocked(&args, rtas_stop_self_token, 0, 1, NULL);
+	raw_rtas_call(&args, rtas_stop_self_token, 0, 1, NULL);
 
 	panic("Alas, I survived.\n");
 }

arch/powerpc/platforms/pseries/ras.c +1 -6

index 74c9b1b5bc66..b009ed7de1ee 100644
@@ -465,12 +465,7 @@ static void fwnmi_release_errinfo(void)
 	struct rtas_args rtas_args;
 	int ret;
 
-	/*
-	 * On pseries, the machine check stack is limited to under 4GB, so
-	 * args can be on-stack.
-	 */
-	rtas_call_unlocked(&rtas_args, ibm_nmi_interlock_token, 0, 1, NULL);
-	ret = be32_to_cpu(rtas_args.rets[0]);
+	ret = raw_rtas_call(&rtas_args, ibm_nmi_interlock_token, 0, 1, NULL);
 	if (ret != 0)
 		printk(KERN_ERR "FWNMI: nmi-interlock failed: %d\n", ret);
 }

arch/powerpc/xmon/xmon.c +1 -1

index fd72753e8ad5..6f53e8bccc33 100644
@@ -410,7 +410,7 @@ static inline void disable_surveillance(void)
 	if (set_indicator_token == RTAS_UNKNOWN_SERVICE)
 		return;
 
-	rtas_call_unlocked(&args, set_indicator_token, 3, 1, NULL,
+	raw_rtas_call(&args, set_indicator_token, 3, 1, NULL,
 			   SURVEILLANCE_TOKEN, 0, 0);
 
 #endif /* CONFIG_PPC_PSERIES */

If buff_copy allocation failed then there was an error and the errbuf allocation succeeded, it will not be logged or freed.

Signed-off-by Nicholas Piggin <[email protected]>

---
 arch/powerpc/kernel/rtas.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

arch/powerpc/kernel/rtas.c +4 -3

index e047793cbb80..1fc22138e3ab 100644
@@ -1239,9 +1239,10 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs)
 
 	unlock_rtas(flags);
 
-	if (buff_copy) {
-		if (errbuf)
-			log_error(errbuf, ERR_TYPE_RTAS_LOG, 0);
+	if (errbuf) {
+		log_error(errbuf, ERR_TYPE_RTAS_LOG, 0);
+		kfree(errbuf);
+	} else if (buff_copy) {
 		kfree(buff_copy);
 	}
 

rtas_call must not be called with the MMU disabled because in case of rtas error, log_error is called which requires MMU enabled. Add a test and warning for this.

Signed-off-by Nicholas Piggin <[email protected]>

---
 arch/powerpc/kernel/rtas.c | 5 +++++
 1 file changed, 5 insertions(+)

arch/powerpc/kernel/rtas.c +5 -0

index 1fc22138e3ab..adf4892aeecd 100644
@@ -479,6 +479,11 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...)
 	if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
 		return -1;
 
+	if ((mfmsr() & (MSR_IR|MSR_DR)) != (MSR_IR|MSR_DR)) {
+		WARN_ON_ONCE(1);
+		return -1;
+	}
+
 	s = lock_rtas();
 
 	/* We use the global rtas args buffer */

Add range checking from the rtas syscall, and other error checks and warnings to kernel callers, so problems can be found and fixed.

Signed-off-by Nicholas Piggin <[email protected]>

---
 arch/powerpc/kernel/rtas.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

arch/powerpc/kernel/rtas.c +6 -0

index adf4892aeecd..7f8a3fd685f9 100644
@@ -428,6 +428,23 @@ static int notrace va_raw_rtas_call(struct rtas_args *args, int token,
 {
 	int i;
 
+	if (!irqs_disabled()) {
+		WARN_ON_ONCE(1);
+		return -1;
+	}
+
+	if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE) {

arch/powerpc/kernel/rtas.c +1 -6

+
 	args->token = cpu_to_be32(token);
 	args->nargs = cpu_to_be32(nargs);
 	args->nret  = cpu_to_be32(nret);

@@ -476,9 +493,6 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...)
 	char *buff_copy = NULL;
 	int ret;
 
-	if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
-		return -1;
-
 	if ((mfmsr() & (MSR_IR|MSR_DR)) != (MSR_IR|MSR_DR)) {
 		WARN_ON_ONCE(1);
 		return -1;

@@ -955,9 +969,6 @@ int rtas_call_reentrant(int token, int nargs, int nret, int *outputs, ...)
 	unsigned long flags;
 	int ret;
 
-	if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
-		return -1;
-
 	local_irq_save(flags);
 	preempt_disable();
 

I had a bunch of random little fixes and cleanups around and was prompted to put them together and make a change to call RTAS with MSR[RI] enabled because of a report of the hard lockup watchdog NMI IPI hitting in an rtas call which then crashed because it's unrecoverable.

Could possibly move patch 9 earlier if it would help with backporting.

Thanks,
Nick

Nicholas Piggin (14):
powerpc/rtas: Move rtas entry assembly into its own file powerpc/rtas: Make enter_rtas a nokprobe symbol on 64-bit powerpc/rtas: Fix whitespace in rtas_entry.S powerpc/rtas: Call enter_rtas with MSR[EE] disabled powerpc/rtas: Modernise RI clearing on 64-bit powerpc/rtas: Load rtas entry MSR explicitly powerpc/rtas: PACA can be restored directly from SPRG powerpc/rtas: call enter_rtas in real-mode on 64-bit powerpc/rtas: Leave MSR[RI] enabled over RTAS call powerpc/rtas: replace rtas_call_unlocked with raw_rtas_call powerpc/rtas: tidy __fetch_rtas_last_error powerpc/rtas: Close theoretical memory leak powerpc/rtas: enture rtas_call is called with MMU enabled powerpc/rtas: Consolidate and improve checking for rtas callers

  arch/powerpc/include/asm/rtas.h              |   4 +-
  arch/powerpc/kernel/Makefile                 |   2 +-
  arch/powerpc/kernel/entry_32.S               |  49 ------
  arch/powerpc/kernel/entry_64.S               | 150 -------------------
  arch/powerpc/kernel/rtas.c                   | 132 +++++++++-------
  arch/powerpc/kernel/rtas_entry.S             | 144 ++++++++++++++++++
  arch/powerpc/platforms/pseries/hotplug-cpu.c |   2 +-
  arch/powerpc/platforms/pseries/ras.c         |   7 +-
  arch/powerpc/xmon/xmon.c                     |   2 +-
  9 files changed, 227 insertions(+), 265 deletions(-)

create mode 100644 arch/powerpc/kernel/rtas_entry.S

I had a bunch of random little fixes and cleanups around and was prompted to put them together and make a change to call RTAS with MSR[RI] enabled because of a report of the hard lockup watchdog NMI IPI hitting in an rtas call which then crashed because it's unrecoverable.

Could possibly move patch 9 earlier if it would help with backporting.

Thanks,
Nick

Nicholas Piggin (14):
powerpc/rtas: Move rtas entry assembly into its own file powerpc/rtas: Make enter_rtas a nokprobe symbol on 64-bit powerpc/rtas: Fix whitespace in rtas_entry.S powerpc/rtas: Call enter_rtas with MSR[EE] disabled powerpc/rtas: Modernise RI clearing on 64-bit powerpc/rtas: Load rtas entry MSR explicitly powerpc/rtas: PACA can be restored directly from SPRG powerpc/rtas: call enter_rtas in real-mode on 64-bit powerpc/rtas: Leave MSR[RI] enabled over RTAS call powerpc/rtas: replace rtas_call_unlocked with raw_rtas_call powerpc/rtas: tidy __fetch_rtas_last_error powerpc/rtas: Close theoretical memory leak powerpc/rtas: enture rtas_call is called with MMU enabled powerpc/rtas: Consolidate and improve checking for rtas callers

 arch/powerpc/include/asm/rtas.h              |   4 +-
 arch/powerpc/kernel/Makefile                 |   2 +-
 arch/powerpc/kernel/entry_32.S               |  49 ------
 arch/powerpc/kernel/entry_64.S               | 150 -------------------
 arch/powerpc/kernel/rtas.c                   | 132 +++++++++-------
 arch/powerpc/kernel/rtas_entry.S             | 144 ++++++++++++++++++
 arch/powerpc/platforms/pseries/hotplug-cpu.c |   2 +-
 arch/powerpc/platforms/pseries/ras.c         |   7 +-
 arch/powerpc/xmon/xmon.c                     |   2 +-
 9 files changed, 227 insertions(+), 265 deletions(-)
 create mode 100644 arch/powerpc/kernel/rtas_entry.S

I had a bunch of random little fixes and cleanups around and was prompted to put them together and make a change to call RTAS with MSR[RI] enabled because of a report of the hard lockup watchdog NMI IPI hitting in an rtas call which then crashed because it's unrecoverable.

Could possibly move patch 9 earlier if it would help with backporting.

[...]