powerpc/32s: Enable CONFIG_VMAP_STACK

A few changes to retrieve DAR and DSISR from struct regs
instead of retrieving them directly, as they may have
changed due to a TLB miss.

Also modifies hash_page() and friends to work with virtual
data addresses instead of physical ones. Same on load_up_fpu()
and load_up_altivec().

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Fix tovirt_vmstack call in head_32.S to fix CHRP build]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2e2509a242fd5f3e23df4a06530c18060c4d321e.1576916812.git.christophe.leroy@c-s.fr

5 files changed, 23 insertions, 5 deletions

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 7e5a1722e4f2..3795654d15d1 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -1339,7 +1339,7 @@ _GLOBAL(enter_rtas)
 	lis	r6,1f@ha	/* physical return address for rtas */
 	addi	r6,r6,1f@l
 	tophys(r6,r6)
-	tophys(r7,r1)
+	tophys_novmstack r7, r1
 	lwz	r8,RTASENTRY(r4)
 	lwz	r4,RTASBASE(r4)
 	mfmsr	r9
diff --git a/arch/powerpc/kernel/fpu.S b/arch/powerpc/kernel/fpu.S
index 0bb991ddd264..3235a8da6af7 100644
--- a/arch/powerpc/kernel/fpu.S
+++ b/arch/powerpc/kernel/fpu.S
@@ -94,6 +94,9 @@ END_FTR_SECTION_IFSET(CPU_FTR_VSX)
 	/* enable use of FP after return */
 #ifdef CONFIG_PPC32
 	mfspr	r5,SPRN_SPRG_THREAD	/* current task's THREAD (phys) */
+#ifdef CONFIG_VMAP_STACK
+	tovirt(r5, r5)
+#endif
 	lwz	r4,THREAD_FPEXC_MODE(r5)
 	ori	r9,r9,MSR_FP		/* enable FP for current */
 	or	r9,r9,r4
diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index 90ef355e958b..0493fcac6409 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -272,14 +272,21 @@ __secondary_hold_acknowledge:
  */
 	. = 0x200
 	DO_KVM  0x200
+MachineCheck:
 	EXCEPTION_PROLOG_0
+#ifdef CONFIG_VMAP_STACK
+	li	r11, MSR_KERNEL & ~(MSR_IR | MSR_RI) /* can take DTLB miss */
+	mtmsr	r11
+	isync
+#endif
 #ifdef CONFIG_PPC_CHRP
 	mfspr	r11, SPRN_SPRG_THREAD
+	tovirt_vmstack r11, r11
 	lwz	r11, RTAS_SP(r11)
 	cmpwi	cr1, r11, 0
 	bne	cr1, 7f
 #endif /* CONFIG_PPC_CHRP */
-	EXCEPTION_PROLOG_1
+	EXCEPTION_PROLOG_1 for_rtas=1
 7:	EXCEPTION_PROLOG_2
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 #ifdef CONFIG_PPC_CHRP
@@ -294,7 +301,7 @@ __secondary_hold_acknowledge:
 	. = 0x300
 	DO_KVM  0x300
 DataAccess:
-	EXCEPTION_PROLOG
+	EXCEPTION_PROLOG handle_dar_dsisr=1
 	get_and_save_dar_dsisr_on_stack	r4, r5, r11
 BEGIN_MMU_FTR_SECTION
 #ifdef CONFIG_PPC_KUAP
@@ -334,7 +341,7 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
 	. = 0x600
 	DO_KVM  0x600
 Alignment:
-	EXCEPTION_PROLOG
+	EXCEPTION_PROLOG handle_dar_dsisr=1
 	save_dar_dsisr_on_stack r4, r5, r11
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	EXC_XFER_STD(0x600, alignment_exception)
@@ -645,6 +652,9 @@ handle_page_fault_tramp_1:
 handle_page_fault_tramp_2:
 	EXC_XFER_LITE(0x300, handle_page_fault)
 
+stack_overflow:
+	vmap_stack_overflow_exception
+
 AltiVecUnavailable:
 	EXCEPTION_PROLOG
 #ifdef CONFIG_ALTIVEC
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index c39209d56020..a6a5fbbf8504 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -38,11 +38,13 @@
 	andi.	r11, r11, MSR_PR
 .endm
 
-.macro EXCEPTION_PROLOG_1
+.macro EXCEPTION_PROLOG_1 for_rtas=0
 #ifdef CONFIG_VMAP_STACK
+	.ifeq	\for_rtas
 	li	r11, MSR_KERNEL & ~(MSR_IR | MSR_RI) /* can take DTLB miss */
 	mtmsr	r11
 	isync
+	.endif
 	subi	r11, r1, INT_FRAME_SIZE		/* use r1 if kernel */
 #else
 	tophys(r11,r1)			/* use tophys(r1) if kernel */
diff --git a/arch/powerpc/kernel/vector.S b/arch/powerpc/kernel/vector.S
index 8eb867dbad5f..25c14a0981bf 100644
--- a/arch/powerpc/kernel/vector.S
+++ b/arch/powerpc/kernel/vector.S
@@ -67,6 +67,9 @@ _GLOBAL(load_up_altivec)
 #ifdef CONFIG_PPC32
 	mfspr	r5,SPRN_SPRG_THREAD		/* current task's THREAD (phys) */
 	oris	r9,r9,MSR_VEC@h
+#ifdef CONFIG_VMAP_STACK
+	tovirt(r5, r5)
+#endif
 #else
 	ld	r4,PACACURRENT(r13)
 	addi	r5,r4,THREAD		/* Get THREAD */