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Message-Id: <d7ba1e34e80898310d6a314cbebe48baa32894ef.1576916812.git.christophe.leroy@c-s.fr>
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From:   Christophe Leroy <christophe.leroy@c-s.fr>
Subject: [PATCH v5 14/17] powerpc/8xx: Enable CONFIG_VMAP_STACK
To:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>, dja@axtens.net
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-mm@kvack.org
Date:   Sat, 21 Dec 2019 08:32:35 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/kernel/head_8xx.S         | 32 ++++++++++++++++++++++++++------
 arch/powerpc/platforms/Kconfig.cputype |  1 +
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 225e242ce1c5..477933b36bde 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 handle_dar_dsisr=1
 	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 handle_dar_dsisr=1
 	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 handle_dar_dsisr=1
 	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 handle_dar_dsisr=1
 	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)
 
@@ -486,22 +492,29 @@ DARFixed:/* Return from dcbx instruction bug workaround */
 	rfi
 #endif
 
+stack_overflow:
+	vmap_stack_overflow_exception
+
 /* On the MPC8xx, these next four traps are used for development
  * support of breakpoints and such.  Someday I will get around to
  * using them.
  */
 do_databreakpoint:
 	EXCEPTION_PROLOG_1
-	EXCEPTION_PROLOG_2
+	EXCEPTION_PROLOG_2 handle_dar_dsisr=1
 	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 handle_dar_dsisr=1
 	mfspr	r11, SPRN_SRR0
 	cmplwi	cr1, r11, (.Ldtlbie - PAGE_OFFSET)@l
 	cmplwi	cr7, r11, (.Litlbie - PAGE_OFFSET)@l
@@ -650,7 +663,14 @@ 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 8d7f9c3dc771..000dd297337c 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