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From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v2 37/45] powerpc/8xx: Refactor kernel address boundary comparison
Date: Wed,  6 May 2020 16:48:43 +0000 (UTC)	[thread overview]
Message-ID: <3db4cecc87f9127752f6246d4306e8c21ca1d56b.1588783498.git.christophe.leroy@csgroup.eu> (raw)
In-Reply-To: <cover.1588783498.git.christophe.leroy@csgroup.eu>

Now that linear and IMMR dedicated TLB handling is gone, kernel
boundary address comparison is similar in ITLB miss handler and
in DTLB miss handler.

Create a macro named compare_to_kernel_boundary.

When TASK_SIZE is strictly below 0x80000000 and PAGE_OFFSET is
above 0x80000000, it is enough to compare to 0x8000000, and this
can be done with a single instruction.

Using not. instruction, we get to use 'blt' conditional branch as
when doing a regular comparison:

0x00000000 <= addr <= 0x7fffffff ==>
0xffffffff >= NOT(addr) >= 0x80000000
The above test corresponds to a 'blt'

Otherwise, do a regular comparison using two instructions.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/kernel/head_8xx.S | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 9f3f7f3d03a7..9a117b9f0998 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -32,10 +32,15 @@
 
 #include "head_32.h"
 
+.macro compare_to_kernel_boundary scratch, addr
 #if CONFIG_TASK_SIZE <= 0x80000000 && CONFIG_PAGE_OFFSET >= 0x80000000
 /* By simply checking Address >= 0x80000000, we know if its a kernel address */
-#define SIMPLE_KERNEL_ADDRESS		1
+	not.	\scratch, \addr
+#else
+	rlwinm	\scratch, \addr, 16, 0xfff8
+	cmpli	cr0, \scratch, PAGE_OFFSET@h
 #endif
+.endm
 
 /*
  * We need an ITLB miss handler for kernel addresses if:
@@ -209,20 +214,11 @@ InstructionTLBMiss:
 	mtspr	SPRN_MD_EPN, r10
 #ifdef ITLB_MISS_KERNEL
 	mfcr	r11
-#if defined(SIMPLE_KERNEL_ADDRESS)
-	cmpi	cr0, r10, 0	/* Address >= 0x80000000 */
-#else
-	rlwinm	r10, r10, 16, 0xfff8
-	cmpli	cr0, r10, PAGE_OFFSET@h
-#endif
+	compare_to_kernel_boundary r10, r10
 #endif
 	mfspr	r10, SPRN_M_TWB	/* Get level 1 table */
 #ifdef ITLB_MISS_KERNEL
-#if defined(SIMPLE_KERNEL_ADDRESS)
-	bge+	3f
-#else
 	blt+	3f
-#endif
 	rlwinm	r10, r10, 0, 20, 31
 	oris	r10, r10, (swapper_pg_dir - PAGE_OFFSET)@ha
 3:
@@ -288,9 +284,7 @@ DataStoreTLBMiss:
 	 * kernel page tables.
 	 */
 	mfspr	r10, SPRN_MD_EPN
-	rlwinm	r10, r10, 16, 0xfff8
-	cmpli	cr0, r10, PAGE_OFFSET@h
-
+	compare_to_kernel_boundary r10, r10
 	mfspr	r10, SPRN_M_TWB	/* Get level 1 table */
 	blt+	3f
 	rlwinm	r10, r10, 0, 20, 31
-- 
2.25.0


  parent reply	other threads:[~2020-05-06 16:49 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-06 16:48 [PATCH v2 00/45] Use hugepages to map kernel mem on 8xx Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 01/45] powerpc/kasan: Fix error detection on memory allocation Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 02/45] powerpc/kasan: Fix issues by lowering KASAN_SHADOW_END Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 03/45] powerpc/kasan: Fix shadow pages allocation failure Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 04/45] powerpc/kasan: Remove unnecessary page table locking Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 05/45] powerpc/kasan: Refactor update of early shadow mappings Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 06/45] powerpc/kasan: Declare kasan_init_region() weak Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 07/45] powerpc/ptdump: Limit size of flags text to 1/2 chars on PPC32 Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 08/45] powerpc/ptdump: Reorder flags Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 09/45] powerpc/ptdump: Add _PAGE_COHERENT flag Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 10/45] powerpc/ptdump: Display size of BATs Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 11/45] powerpc/ptdump: Standardise display of BAT flags Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 12/45] powerpc/ptdump: Properly handle non standard page size Christophe Leroy
2020-05-07 16:12   ` kbuild test robot
2020-05-06 16:48 ` [PATCH v2 13/45] powerpc/ptdump: Handle hugepd at PGD level Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 14/45] powerpc/32s: Don't warn when mapping RO data ROX Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 15/45] powerpc/mm: Allocate static page tables for fixmap Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 16/45] powerpc/mm: Fix conditions to perform MMU specific management by blocks on PPC32 Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 17/45] powerpc/mm: PTE_ATOMIC_UPDATES is only for 40x Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 18/45] powerpc/mm: Refactor pte_update() on nohash/32 Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 19/45] powerpc/mm: Refactor pte_update() on book3s/32 Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 20/45] powerpc/mm: Standardise __ptep_test_and_clear_young() params between PPC32 and PPC64 Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 21/45] powerpc/mm: Standardise pte_update() prototype " Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 22/45] powerpc/mm: Create a dedicated pte_update() for 8xx Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 23/45] powerpc/mm: Reduce hugepd size for 8M hugepages on 8xx Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 24/45] powerpc/8xx: Drop CONFIG_8xx_COPYBACK option Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 25/45] powerpc/8xx: Prepare handlers for _PAGE_HUGE for 512k pages Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 26/45] powerpc/8xx: Manage 512k huge pages as standard pages Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 27/45] powerpc/8xx: Only 8M pages are hugepte pages now Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 28/45] powerpc/8xx: MM_SLICE is not needed anymore Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 29/45] powerpc/8xx: Move PPC_PIN_TLB options into 8xx Kconfig Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 30/45] powerpc/8xx: Add function to set pinned TLBs Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 31/45] powerpc/8xx: Don't set IMMR map anymore at boot Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 32/45] powerpc/8xx: Always pin TLBs at startup Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 33/45] powerpc/8xx: Drop special handling of Linear and IMMR mappings in I/D TLB handlers Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 34/45] powerpc/8xx: Remove now unused TLB miss functions Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 35/45] powerpc/8xx: Move DTLB perf handling closer Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 36/45] powerpc/mm: Don't be too strict with _etext alignment on PPC32 Christophe Leroy
2020-05-06 16:48 ` Christophe Leroy [this message]
2020-05-06 16:48 ` [PATCH v2 38/45] powerpc/8xx: Add a function to early map kernel via huge pages Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 39/45] powerpc/8xx: Map IMMR with a huge page Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 40/45] powerpc/8xx: Map linear memory with huge pages Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 41/45] powerpc/8xx: Allow STRICT_KERNEL_RwX with pinned TLB Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 42/45] powerpc/8xx: Allow large TLBs with DEBUG_PAGEALLOC Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 43/45] powerpc/8xx: Implement dedicated kasan_init_region() Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 44/45] powerpc/32s: Allow mapping with BATs with DEBUG_PAGEALLOC Christophe Leroy
2020-05-06 16:48 ` [PATCH v2 45/45] powerpc/32s: Implement dedicated kasan_init_region() Christophe Leroy

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