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

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

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

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

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 */

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 */

arch/powerpc/mm/book3s32/hash_low.S

@@ -25,6 +25,12 @@
 #include <asm/feature-fixups.h>
 #include <asm/code-patching-asm.h>
 
+#ifdef CONFIG_VMAP_STACK
+#define ADDR_OFFSET	0
+#else
+#define ADDR_OFFSET	PAGE_OFFSET
+#endif
+
 #ifdef CONFIG_SMP
 	.section .bss
 	.align	2
@@ -47,8 +53,8 @@ mmu_hash_lock:
 	.text
 _GLOBAL(hash_page)
 #ifdef CONFIG_SMP
-	lis	r8, (mmu_hash_lock - PAGE_OFFSET)@h
-	ori	r8, r8, (mmu_hash_lock - PAGE_OFFSET)@l
+	lis	r8, (mmu_hash_lock - ADDR_OFFSET)@h
+	ori	r8, r8, (mmu_hash_lock - ADDR_OFFSET)@l
 	lis	r0,0x0fff
 	b	10f
 11:	lwz	r6,0(r8)
@@ -66,9 +72,12 @@ _GLOBAL(hash_page)
 	cmplw	0,r4,r0
 	ori	r3,r3,_PAGE_USER|_PAGE_PRESENT /* test low addresses as user */
 	mfspr	r5, SPRN_SPRG_PGDIR	/* phys page-table root */
+#ifdef CONFIG_VMAP_STACK
+	tovirt(r5, r5)
+#endif
 	blt+	112f			/* assume user more likely */
-	lis	r5, (swapper_pg_dir - PAGE_OFFSET)@ha	/* if kernel address, use */
-	addi	r5 ,r5 ,(swapper_pg_dir - PAGE_OFFSET)@l	/* kernel page table */
+	lis	r5, (swapper_pg_dir - ADDR_OFFSET)@ha	/* if kernel address, use */
+	addi	r5 ,r5 ,(swapper_pg_dir - ADDR_OFFSET)@l	/* kernel page table */
 	rlwimi	r3,r9,32-12,29,29	/* MSR_PR -> _PAGE_USER */
 112:
 #ifndef CONFIG_PTE_64BIT
@@ -80,6 +89,9 @@ _GLOBAL(hash_page)
 	lwzx	r8,r8,r5		/* Get L1 entry */
 	rlwinm.	r8,r8,0,0,20		/* extract pt base address */
 #endif
+#ifdef CONFIG_VMAP_STACK
+	tovirt(r8, r8)
+#endif
 #ifdef CONFIG_SMP
 	beq-	hash_page_out		/* return if no mapping */
 #else
@@ -137,9 +149,9 @@ retry:
 
 #ifdef CONFIG_SMP
 	eieio
-	lis	r8, (mmu_hash_lock - PAGE_OFFSET)@ha
+	lis	r8, (mmu_hash_lock - ADDR_OFFSET)@ha
 	li	r0,0
-	stw	r0, (mmu_hash_lock - PAGE_OFFSET)@l(r8)
+	stw	r0, (mmu_hash_lock - ADDR_OFFSET)@l(r8)
 #endif
 
 	/* Return from the exception */
@@ -152,9 +164,9 @@ retry:
 #ifdef CONFIG_SMP
 hash_page_out:
 	eieio
-	lis	r8, (mmu_hash_lock - PAGE_OFFSET)@ha
+	lis	r8, (mmu_hash_lock - ADDR_OFFSET)@ha
 	li	r0,0
-	stw	r0, (mmu_hash_lock - PAGE_OFFSET)@l(r8)
+	stw	r0, (mmu_hash_lock - ADDR_OFFSET)@l(r8)
 	blr
 #endif /* CONFIG_SMP */
 
@@ -329,7 +341,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
 	patch_site	1f, patch__hash_page_A1
 	patch_site	2f, patch__hash_page_A2
 	/* Get the address of the primary PTE group in the hash table (r3) */
-0:	lis	r0, (Hash_base - PAGE_OFFSET)@h	/* base address of hash table */
+0:	lis	r0, (Hash_base - ADDR_OFFSET)@h	/* base address of hash table */
 1:	rlwimi	r0,r3,LG_PTEG_SIZE,HASH_LEFT,HASH_RIGHT    /* VSID -> hash */
 2:	rlwinm	r3,r4,20+LG_PTEG_SIZE,HASH_LEFT,HASH_RIGHT /* PI -> hash */
 	xor	r3,r3,r0		/* make primary hash */
@@ -343,10 +355,10 @@ END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
 	beq+	10f			/* no PTE: go look for an empty slot */
 	tlbie	r4
 
-	lis	r4, (htab_hash_searches - PAGE_OFFSET)@ha
-	lwz	r6, (htab_hash_searches - PAGE_OFFSET)@l(r4)
+	lis	r4, (htab_hash_searches - ADDR_OFFSET)@ha
+	lwz	r6, (htab_hash_searches - ADDR_OFFSET)@l(r4)
 	addi	r6,r6,1			/* count how many searches we do */
-	stw	r6, (htab_hash_searches - PAGE_OFFSET)@l(r4)
+	stw	r6, (htab_hash_searches - ADDR_OFFSET)@l(r4)
 
 	/* Search the primary PTEG for a PTE whose 1st (d)word matches r5 */
 	mtctr	r0
@@ -378,10 +390,10 @@ END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
 	beq+	found_empty
 
 	/* update counter of times that the primary PTEG is full */
-	lis	r4, (primary_pteg_full - PAGE_OFFSET)@ha
-	lwz	r6, (primary_pteg_full - PAGE_OFFSET)@l(r4)
+	lis	r4, (primary_pteg_full - ADDR_OFFSET)@ha
+	lwz	r6, (primary_pteg_full - ADDR_OFFSET)@l(r4)
 	addi	r6,r6,1
-	stw	r6, (primary_pteg_full - PAGE_OFFSET)@l(r4)
+	stw	r6, (primary_pteg_full - ADDR_OFFSET)@l(r4)
 
 	patch_site	0f, patch__hash_page_C
 	/* Search the secondary PTEG for an empty slot */
@@ -415,8 +427,8 @@ END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
 	 * lockup here but that shouldn't happen
 	 */
 
-1:	lis	r4, (next_slot - PAGE_OFFSET)@ha	/* get next evict slot */
-	lwz	r6, (next_slot - PAGE_OFFSET)@l(r4)
+1:	lis	r4, (next_slot - ADDR_OFFSET)@ha	/* get next evict slot */
+	lwz	r6, (next_slot - ADDR_OFFSET)@l(r4)
 	addi	r6,r6,HPTE_SIZE			/* search for candidate */
 	andi.	r6,r6,7*HPTE_SIZE
 	stw	r6,next_slot@l(r4)

arch/powerpc/mm/book3s32/mmu.c

@@ -413,6 +413,7 @@ void __init MMU_init_hw(void)
 void __init MMU_init_hw_patch(void)
 {
 	unsigned int hmask = Hash_mask >> (16 - LG_HPTEG_SIZE);
+	unsigned int hash;
 
 	if (ppc_md.progress)
 		ppc_md.progress("hash:patch", 0x345);
@@ -424,8 +425,12 @@ void __init MMU_init_hw_patch(void)
 	/*
 	 * Patch up the instructions in hashtable.S:create_hpte
 	 */
-	modify_instruction_site(&patch__hash_page_A0, 0xffff,
-				((unsigned int)Hash - PAGE_OFFSET) >> 16);
+	if (IS_ENABLED(CONFIG_VMAP_STACK))
+		hash = (unsigned int)Hash;
+	else
+		hash = (unsigned int)Hash - PAGE_OFFSET;
+
+	modify_instruction_site(&patch__hash_page_A0, 0xffff, hash >> 16);
 	modify_instruction_site(&patch__hash_page_A1, 0x7c0, hash_mb << 6);
 	modify_instruction_site(&patch__hash_page_A2, 0x7c0, hash_mb2 << 6);
 	modify_instruction_site(&patch__hash_page_B, 0xffff, hmask);

arch/powerpc/platforms/Kconfig.cputype

@@ -31,12 +31,14 @@ config PPC_BOOK3S_6xx
 	select PPC_HAVE_PMU_SUPPORT
 	select PPC_HAVE_KUEP
 	select PPC_HAVE_KUAP
+	select HAVE_ARCH_VMAP_STACK
 
 config PPC_BOOK3S_601
 	bool "PowerPC 601"
 	select PPC_BOOK3S_32
 	select PPC_FPU
 	select PPC_HAVE_KUAP
+	select HAVE_ARCH_VMAP_STACK
 
 config PPC_85xx
 	bool "Freescale 85xx"