linux-kernel - [PATCH v3 21/22] powerpc/kuap: Wire-up KUAP on book3e/64

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Message-Id: <e2c2c9375afd4bbc06aa904d0103a5f5102a2b1a.1634627931.git.christophe.leroy@csgroup.eu>
Date:   Tue, 19 Oct 2021 09:29:32 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v3 21/22] powerpc/kuap: Wire-up KUAP on book3e/64

This adds KUAP support to book3e/64.
This is done by reading the content of SPRN_MAS1 and checking
the TID at the time user pgtable is loaded.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/mm/nohash/tlb_low_64e.S   | 40 ++++++++++++++++++++++----
 arch/powerpc/platforms/Kconfig.cputype |  1 +
 2 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/mm/nohash/tlb_low_64e.S b/arch/powerpc/mm/nohash/tlb_low_64e.S
index bf24451f3e71..b43524ca2b95 100644
--- a/arch/powerpc/mm/nohash/tlb_low_64e.S
+++ b/arch/powerpc/mm/nohash/tlb_low_64e.S
@@ -128,6 +128,13 @@ END_BTB_FLUSH_SECTION
 
 	bne	tlb_miss_kernel_bolted
 
+tlb_miss_user_bolted:
+#ifdef CONFIG_PPC_KUAP
+	mfspr	r10,SPRN_MAS1
+	rlwinm.	r10,r10,0,0x3fff0000
+	beq-	tlb_miss_fault_bolted /* KUAP fault */
+#endif
+
 tlb_miss_common_bolted:
 /*
  * This is the guts of the TLB miss handler for bolted-linear.
@@ -246,7 +253,7 @@ itlb_miss_fault_bolted:
 
 	cmpldi	cr0,r15,0			/* Check for user region */
 	oris	r11,r11,_PAGE_ACCESSED@h
-	beq	tlb_miss_common_bolted
+	beq	tlb_miss_user_bolted
 	b	itlb_miss_kernel_bolted
 
 #ifdef CONFIG_PPC_FSL_BOOK3E
@@ -676,6 +683,11 @@ finish_normal_tlb_miss:
 	/* Check if required permissions are met */
 	andc.	r15,r11,r14
 	bne-	normal_tlb_miss_access_fault
+#ifdef CONFIG_PPC_KUAP
+	mfspr	r11,SPRN_MAS1
+	rlwinm.	r10,r11,0,0x3fff0000
+	beq-	normal_tlb_miss_access_fault /* KUAP fault */
+#endif
 
 	/* Now we build the MAS:
 	 *
@@ -689,15 +701,17 @@ finish_normal_tlb_miss:
 	 *
 	 * TODO: mix up code below for better scheduling
 	 */
-	clrrdi	r11,r16,12		/* Clear low crap in EA */
-	rlwimi	r11,r14,32-19,27,31	/* Insert WIMGE */
-	mtspr	SPRN_MAS2,r11
+	clrrdi	r10,r16,12		/* Clear low crap in EA */
+	rlwimi	r10,r14,32-19,27,31	/* Insert WIMGE */
+	mtspr	SPRN_MAS2,r10
 
 	/* Check page size, if not standard, update MAS1 */
-	rldicl	r11,r14,64-8,64-8
-	cmpldi	cr0,r11,BOOK3E_PAGESZ_4K
+	rldicl	r10,r14,64-8,64-8
+	cmpldi	cr0,r10,BOOK3E_PAGESZ_4K
 	beq-	1f
+#ifndef CONFIG_PPC_KUAP
 	mfspr	r11,SPRN_MAS1
+#endif
 	rlwimi	r11,r14,31,21,24
 	rlwinm	r11,r11,0,21,19
 	mtspr	SPRN_MAS1,r11
@@ -786,7 +800,16 @@ virt_page_table_tlb_miss:
 	mfspr	r10,SPRN_MAS1
 	rlwinm	r10,r10,0,16,1			/* Clear TID */
 	mtspr	SPRN_MAS1,r10
+#ifdef CONFIG_PPC_KUAP
+	b	2f
+1:
+	mfspr	r10,SPRN_MAS1
+	rlwinm.	r10,r10,0,0x3fff0000
+	beq-	virt_page_table_tlb_miss_fault /* KUAP fault */
+2:
+#else
 1:
+#endif
 BEGIN_MMU_FTR_SECTION
 	/* Search if we already have a TLB entry for that virtual address, and
 	 * if we do, bail out.
@@ -1027,6 +1050,11 @@ virt_page_table_tlb_miss_whacko_fault:
  * avoid too much complication, it will save/restore things for us
  */
 htw_tlb_miss:
+#ifdef CONFIG_PPC_KUAP
+	mfspr	r10,SPRN_MAS1
+	rlwinm.	r10,r10,0,0x3fff0000
+	beq-	htw_tlb_miss_fault /* KUAP fault */
+#endif
 	/* Search if we already have a TLB entry for that virtual address, and
 	 * if we do, bail out.
 	 *
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 611d6efc047b..f3614bfd47ad 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -122,6 +122,7 @@ config PPC_BOOK3E_64
 	select PPC_SMP_MUXED_IPI
 	select PPC_DOORBELL
 	select ZONE_DMA
+	select PPC_HAVE_KUAP
 
 endchoice
 
-- 
2.31.1