From: Anshuman Khandual <anshuman.khandual@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: mark.rutland@arm.com, catalin.marinas@arm.com, will@kernel.org,
Anshuman Khandual <anshuman.khandual@arm.com>
Subject: [PATCH 5/6] arm64: head: clarify `map_memory`
Date: Wed, 18 May 2022 08:47:24 +0530 [thread overview]
Message-ID: <20220518031725.3128044-6-anshuman.khandual@arm.com> (raw)
In-Reply-To: <20220518031725.3128044-1-anshuman.khandual@arm.com>
From: Mark Rutland <mark.rutland@arm.com>
In the `map_memory` macro we repurpose the `count` temporary register to
hold the physical address `phys` aligned downwards to
SWAPPER_BLOCK_SIZE. Due to the subtle usage of `count` elsewhere, this
is a little confusing, and is also unnecessary as we can safely corrupt
`phys`, which is not used after `map_memory` completes.
This patch makes `map_memory` manipulate `phys` in-place, and updates
the documentation to mention that it corrupts `phys`.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
arch/arm64/kernel/head.S | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 01739f5ec3de..107275e06212 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -225,7 +225,7 @@ SYM_CODE_END(preserve_boot_args)
*
* Temporaries: istart, iend, tmp, count, sv - these need to be different registers
* Preserves: vstart, flags
- * Corrupts: tbl, rtbl, vend, istart, iend, tmp, count, sv
+ * Corrupts: tbl, rtbl, vend, phys, istart, iend, tmp, count, sv
*/
.macro map_memory, tbl, rtbl, vstart, vend, flags, phys, pgds, istart, iend, tmp, count, sv
sub \vend, \vend, #1
@@ -251,8 +251,8 @@ SYM_CODE_END(preserve_boot_args)
#endif
compute_indices \vstart, \vend, #SWAPPER_BLOCK_SHIFT, #PTRS_PER_PTE, \istart, \iend, \count, \tmp
- bic \count, \phys, #SWAPPER_BLOCK_SIZE - 1
- populate_entries \tbl, \count, \istart, \iend, \flags, #SWAPPER_BLOCK_SIZE, \tmp
+ bic \phys, \phys, #SWAPPER_BLOCK_SIZE - 1
+ populate_entries \tbl, \phys, \istart, \iend, \flags, #SWAPPER_BLOCK_SIZE, \tmp
.endm
/*
--
2.20.1
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next prev parent reply other threads:[~2022-05-18 3:19 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-18 3:17 [PATCH 0/6] arm64/head: Cleanups for __create_page_tables() Anshuman Khandual
2022-05-18 3:17 ` [PATCH 1/6] arm64: don't override idmap t0sz Anshuman Khandual
2022-05-18 6:41 ` Ard Biesheuvel
2022-05-18 3:17 ` [PATCH 2/6] arm64: head: remove __PHYS_OFFSET Anshuman Khandual
2022-05-18 6:45 ` Ard Biesheuvel
2022-05-18 3:17 ` [PATCH 3/6] arm64: head: clarify `populate_entries` Anshuman Khandual
2022-05-18 3:17 ` [PATCH 4/6] arm64: head: clarify `compute_indices` Anshuman Khandual
2022-05-18 6:47 ` Ard Biesheuvel
2022-05-18 3:17 ` Anshuman Khandual [this message]
2022-05-18 3:17 ` [PATCH 6/6] arm64: head: clarify commentary for __create_page_tables Anshuman Khandual
2022-05-18 6:52 ` [PATCH 0/6] arm64/head: Cleanups for __create_page_tables() Ard Biesheuvel
2022-05-18 9:35 ` Anshuman Khandual
2022-06-27 10:17 ` Will Deacon
2022-06-28 4:47 ` Anshuman Khandual
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