linux-kernel - [PATCH v17 06/15] arm64: kexec: Use dcache ops macros instead of open-coding

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Message-Id: <20210916231325.125533-7-pasha.tatashin@soleen.com>
Date:   Thu, 16 Sep 2021 19:13:16 -0400
From:   Pasha Tatashin <pasha.tatashin@...een.com>
To:     pasha.tatashin@...een.com, jmorris@...ei.org, sashal@...nel.org,
        ebiederm@...ssion.com, kexec@...ts.infradead.org,
        linux-kernel@...r.kernel.org, corbet@....net,
        catalin.marinas@....com, will@...nel.org,
        linux-arm-kernel@...ts.infradead.org, maz@...nel.org,
        james.morse@....com, vladimir.murzin@....com,
        matthias.bgg@...il.com, linux-mm@...ck.org, mark.rutland@....com,
        steve.capper@....com, rfontana@...hat.com, tglx@...utronix.de,
        selindag@...il.com, tyhicks@...ux.microsoft.com,
        kernelfans@...il.com, akpm@...ux-foundation.org,
        madvenka@...ux.microsoft.com
Subject: [PATCH v17 06/15] arm64: kexec: Use dcache ops macros instead of open-coding

kexec does dcache maintenance when it re-writes all memory. Our
dcache_by_line_op macro depends on reading the sanitized DminLine
from memory. Kexec may have overwritten this, so open-codes the
sequence.

dcache_by_line_op is a whole set of macros, it uses dcache_line_size
which uses read_ctr for the sanitsed DminLine. Reading the DminLine
is the first thing the dcache_by_line_op does.

Rename dcache_by_line_op dcache_by_myline_op and take DminLine as
an argument. Kexec can now use the slightly smaller macro.

This makes up-coming changes to the dcache maintenance easier on
the eye.

Code generated by the existing callers is unchanged.

Suggested-by: James Morse <james.morse@....com>
Signed-off-by: Pasha Tatashin <pasha.tatashin@...een.com>
---
 arch/arm64/include/asm/assembler.h  | 30 ++++++++++++++++++++++-------
 arch/arm64/kernel/relocate_kernel.S | 13 +++----------
 2 files changed, 26 insertions(+), 17 deletions(-)

diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 89faca0e740d..71999a325055 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -405,19 +405,19 @@ alternative_endif
 
 /*
  * Macro to perform a data cache maintenance for the interval
- * [start, end)
+ * [start, end) with dcache line size explicitly provided.
  *
  * 	op:		operation passed to dc instruction
  * 	domain:		domain used in dsb instruciton
  * 	start:          starting virtual address of the region
  * 	end:            end virtual address of the region
+ *	linesz:		dcache line size
  * 	fixup:		optional label to branch to on user fault
- * 	Corrupts:       start, end, tmp1, tmp2
+ * 	Corrupts:       start, end, tmp
  */
-	.macro dcache_by_line_op op, domain, start, end, tmp1, tmp2, fixup
-	dcache_line_size \tmp1, \tmp2
-	sub	\tmp2, \tmp1, #1
-	bic	\start, \start, \tmp2
+	.macro dcache_by_myline_op op, domain, start, end, linesz, tmp, fixup
+	sub	\tmp, \linesz, #1
+	bic	\start, \start, \tmp
 .Ldcache_op\@:
 	.ifc	\op, cvau
 	__dcache_op_workaround_clean_cache \op, \start
@@ -436,7 +436,7 @@ alternative_endif
 	.endif
 	.endif
 	.endif
-	add	\start, \start, \tmp1
+	add	\start, \start, \linesz
 	cmp	\start, \end
 	b.lo	.Ldcache_op\@
 	dsb	\domain
@@ -444,6 +444,22 @@ alternative_endif
 	_cond_extable .Ldcache_op\@, \fixup
 	.endm
 
+/*
+ * Macro to perform a data cache maintenance for the interval
+ * [start, end)
+ *
+ * 	op:		operation passed to dc instruction
+ * 	domain:		domain used in dsb instruciton
+ * 	start:          starting virtual address of the region
+ * 	end:            end virtual address of the region
+ * 	fixup:		optional label to branch to on user fault
+ * 	Corrupts:       start, end, tmp1, tmp2
+ */
+	.macro dcache_by_line_op op, domain, start, end, tmp1, tmp2, fixup
+	dcache_line_size \tmp1, \tmp2
+	dcache_by_myline_op \op, \domain, \start, \end, \tmp1, \tmp2, \fixup
+	.endm
+
 /*
  * Macro to perform an instruction cache maintenance for the interval
  * [start, end)
diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S
index 8058fabe0a76..8c43779e8cc6 100644
--- a/arch/arm64/kernel/relocate_kernel.S
+++ b/arch/arm64/kernel/relocate_kernel.S
@@ -41,16 +41,9 @@ SYM_CODE_START(arm64_relocate_new_kernel)
 	tbz	x16, IND_SOURCE_BIT, .Ltest_indirection
 
 	/* Invalidate dest page to PoC. */
-	mov     x2, x13
-	add     x20, x2, #PAGE_SIZE
-	sub     x1, x15, #1
-	bic     x2, x2, x1
-2:	dc      ivac, x2
-	add     x2, x2, x15
-	cmp     x2, x20
-	b.lo    2b
-	dsb     sy
-
+	mov	x2, x13
+	add	x1, x2, #PAGE_SIZE
+	dcache_by_myline_op ivac, sy, x2, x1, x15, x20
 	copy_page x13, x12, x1, x2, x3, x4, x5, x6, x7, x8
 	b	.Lnext
 .Ltest_indirection:
-- 
2.25.1