[PATCH v4 13/16] powerpc/8xx: Enable CONFIG_VMAP_STACK

[Christophe Leroy]

This patch enables CONFIG_VMAP_STACK. For that, a few changes are
done in head_8xx.S.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
 arch/powerpc/kernel/head_8xx.S         | 34 ++++++++++++++++++++++++++++------
 arch/powerpc/platforms/Kconfig.cputype |  1 +
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 225e242ce1c5..fc6d4d10e298 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -127,7 +127,7 @@ instruction_counter:
 /* Machine check */
 	. = 0x200
 MachineCheck:
-	EXCEPTION_PROLOG
+	EXCEPTION_PROLOG dar
 	save_dar_dsisr_on_stack r4, r5, r11
 	li	r6, RPN_PATTERN
 	mtspr	SPRN_DAR, r6	/* Tag DAR, to be used in DTLB Error */
@@ -140,7 +140,7 @@ MachineCheck:
 /* Alignment exception */
 	. = 0x600
 Alignment:
-	EXCEPTION_PROLOG
+	EXCEPTION_PROLOG dar
 	save_dar_dsisr_on_stack r4, r5, r11
 	li	r6, RPN_PATTERN
 	mtspr	SPRN_DAR, r6	/* Tag DAR, to be used in DTLB Error */
@@ -457,20 +457,26 @@ InstructionTLBError:
  */
 	. = 0x1400
 DataTLBError:
-	EXCEPTION_PROLOG_0
+	EXCEPTION_PROLOG_0 dar
 	mfspr	r11, SPRN_DAR
 	cmpwi	cr1, r11, RPN_PATTERN
 	beq-	cr1, FixupDAR	/* must be a buggy dcbX, icbi insn. */
 DARFixed:/* Return from dcbx instruction bug workaround */
+#ifdef CONFIG_VMAP_STACK
+	li	r11, RPN_PATTERN
+	mtspr	SPRN_DAR, r11	/* Tag DAR, to be used in DTLB Error */
+#endif
 	EXCEPTION_PROLOG_1
-	EXCEPTION_PROLOG_2
+	EXCEPTION_PROLOG_2 dar
 	get_and_save_dar_dsisr_on_stack r4, r5, r11
 	andis.	r10,r5,DSISR_NOHPTE@h
 	beq+	.Ldtlbie
 	tlbie	r4
 .Ldtlbie:
+#ifndef CONFIG_VMAP_STACK
 	li	r10,RPN_PATTERN
 	mtspr	SPRN_DAR,r10	/* Tag DAR, to be used in DTLB Error */
+#endif
 	/* 0x300 is DataAccess exception, needed by bad_page_fault() */
 	EXC_XFER_LITE(0x300, handle_page_fault)
 
@@ -492,16 +498,20 @@ DARFixed:/* Return from dcbx instruction bug workaround */
  */
 do_databreakpoint:
 	EXCEPTION_PROLOG_1
-	EXCEPTION_PROLOG_2
+	EXCEPTION_PROLOG_2 dar
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	mfspr	r4,SPRN_BAR
 	stw	r4,_DAR(r11)
+#ifdef CONFIG_VMAP_STACK
+	lwz	r5,_DSISR(r11)
+#else
 	mfspr	r5,SPRN_DSISR
+#endif
 	EXC_XFER_STD(0x1c00, do_break)
 
 	. = 0x1c00
 DataBreakpoint:
-	EXCEPTION_PROLOG_0
+	EXCEPTION_PROLOG_0 dar
 	mfspr	r11, SPRN_SRR0
 	cmplwi	cr1, r11, (.Ldtlbie - PAGE_OFFSET)@l
 	cmplwi	cr7, r11, (.Litlbie - PAGE_OFFSET)@l
@@ -530,6 +540,11 @@ InstructionBreakpoint:
 	EXCEPTION(0x1e00, Trap_1e, unknown_exception, EXC_XFER_STD)
 	EXCEPTION(0x1f00, Trap_1f, unknown_exception, EXC_XFER_STD)
 
+#ifdef CONFIG_VMAP_STACK
+stack_ovf_trampoline:
+	b	stack_ovf
+#endif
+
 	. = 0x2000
 
 /* This is the procedure to calculate the data EA for buggy dcbx,dcbi instructions
@@ -650,7 +665,14 @@ FixupDAR:/* Entry point for dcbx workaround. */
 152:
 	mfdar	r11
 	mtctr	r11			/* restore ctr reg from DAR */
+#ifdef CONFIG_VMAP_STACK
+	mfspr	r11, SPRN_SPRG_THREAD
+	stw	r10, DAR(r11)
+	mfspr	r10, SPRN_DSISR
+	stw	r10, DSISR(r11)
+#else
 	mtdar	r10			/* save fault EA to DAR */
+#endif
 	mfspr	r10,SPRN_M_TW
 	b	DARFixed		/* Go back to normal TLB handling */
 
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 1e352c2eea7a..f0583251e9a3 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -49,6 +49,7 @@ config PPC_8xx
 	select PPC_HAVE_KUEP
 	select PPC_HAVE_KUAP
 	select PPC_MM_SLICES if HUGETLB_PAGE
+	select HAVE_ARCH_VMAP_STACK
 
 config 40x
 	bool "AMCC 40x"
-- 
2.13.3