linux-kernel - [PATCH v9 11/18] arm64: kexec: arm64_relocate_new

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Message-Id: <20200326032420.27220-12-pasha.tatashin@soleen.com>
Date:   Wed, 25 Mar 2020 23:24:13 -0400
From:   Pavel 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, bhsharma@...hat.com, linux-mm@...ck.org,
        mark.rutland@....com, steve.capper@....com, rfontana@...hat.com,
        tglx@...utronix.de, selindag@...il.com
Subject: [PATCH v9 11/18] arm64: kexec: arm64_relocate_new_kernel clean-ups

Remove excessive empty lines from arm64_relocate_new_kernel.
Also, use comments on the same lines with instructions where
appropriate.

Change ENDPROC to END it never returns.

copy_page(dest, src, tmps...)
Increments dest and src by PAGE_SIZE, so no need to store dest
prior to calling copy_page and increment it after. Also, src is not
used after a copy, not need to copy either.

Call raw_dcache_line_size()  only when relocation is actually going to
happen.

Since '.align 3' is intended to align globals at the end of the file,
move it there.

Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
---
 arch/arm64/kernel/relocate_kernel.S | 50 +++++++----------------------
 1 file changed, 11 insertions(+), 39 deletions(-)

diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S
index c1d7db71a726..e9c974ea4717 100644
--- a/arch/arm64/kernel/relocate_kernel.S
+++ b/arch/arm64/kernel/relocate_kernel.S
@@ -8,7 +8,6 @@
 
 #include <linux/kexec.h>
 #include <linux/linkage.h>
-
 #include <asm/assembler.h>
 #include <asm/kexec.h>
 #include <asm/page.h>
@@ -17,25 +16,21 @@
 /*
  * arm64_relocate_new_kernel - Put a 2nd stage image in place and boot it.
  *
- * The memory that the old kernel occupies may be overwritten when coping the
+ * The memory that the old kernel occupies may be overwritten when copying the
  * new image to its final location.  To assure that the
  * arm64_relocate_new_kernel routine which does that copy is not overwritten,
  * all code and data needed by arm64_relocate_new_kernel must be between the
  * symbols arm64_relocate_new_kernel and arm64_relocate_new_kernel_end.  The
  * machine_kexec() routine will copy arm64_relocate_new_kernel to the kexec
- * control_code_page, a special page which has been set up to be preserved
- * during the copy operation.
+ * safe memory that has been set up to be preserved during the copy operation.
  */
 ENTRY(arm64_relocate_new_kernel)
-
 	/* Setup the list loop variables. */
 	mov	x18, x2				/* x18 = dtb address */
 	mov	x17, x1				/* x17 = kimage_start */
 	mov	x16, x0				/* x16 = kimage_head */
-	raw_dcache_line_size x15, x0		/* x15 = dcache line size */
 	mov	x14, xzr			/* x14 = entry ptr */
 	mov	x13, xzr			/* x13 = copy dest */
-
 	/* Clear the sctlr_el2 flags. */
 	mrs	x0, CurrentEL
 	cmp	x0, #CurrentEL_EL2
@@ -46,14 +41,11 @@ ENTRY(arm64_relocate_new_kernel)
 	pre_disable_mmu_workaround
 	msr	sctlr_el2, x0
 	isb
-1:
-
-	/* Check if the new image needs relocation. */
+1:	/* Check if the new image needs relocation. */
 	tbnz	x16, IND_DONE_BIT, .Ldone
-
+	raw_dcache_line_size x15, x1		/* x15 = dcache line size */
 .Lloop:
 	and	x12, x16, PAGE_MASK		/* x12 = addr */
-
 	/* Test the entry flags. */
 .Ltest_source:
 	tbz	x16, IND_SOURCE_BIT, .Ltest_indirection
@@ -69,34 +61,18 @@ ENTRY(arm64_relocate_new_kernel)
 	b.lo    2b
 	dsb     sy
 
-	mov x20, x13
-	mov x21, x12
-	copy_page x20, x21, x0, x1, x2, x3, x4, x5, x6, x7
-
-	/* dest += PAGE_SIZE */
-	add	x13, x13, PAGE_SIZE
+	copy_page x13, x12, x0, x1, x2, x3, x4, x5, x6, x7
 	b	.Lnext
-
 .Ltest_indirection:
 	tbz	x16, IND_INDIRECTION_BIT, .Ltest_destination
-
-	/* ptr = addr */
-	mov	x14, x12
+	mov	x14, x12			/* ptr = addr */
 	b	.Lnext
-
 .Ltest_destination:
 	tbz	x16, IND_DESTINATION_BIT, .Lnext
-
-	/* dest = addr */
-	mov	x13, x12
-
+	mov	x13, x12			/* dest = addr */
 .Lnext:
-	/* entry = *ptr++ */
-	ldr	x16, [x14], #8
-
-	/* while (!(entry & DONE)) */
-	tbz	x16, IND_DONE_BIT, .Lloop
-
+	ldr	x16, [x14], #8			/* entry = *ptr++ */
+	tbz	x16, IND_DONE_BIT, .Lloop	/* while (!(entry & DONE)) */
 .Ldone:
 	/* wait for writes from copy_page to finish */
 	dsb	nsh
@@ -110,16 +86,12 @@ ENTRY(arm64_relocate_new_kernel)
 	mov	x2, xzr
 	mov	x3, xzr
 	br	x17
-
-ENDPROC(arm64_relocate_new_kernel)
-
 .ltorg
-
-.align 3	/* To keep the 64-bit values below naturally aligned. */
+END(arm64_relocate_new_kernel)
 
 .Lcopy_end:
 .org	KEXEC_CONTROL_PAGE_SIZE
-
+.align 3	/* To keep the 64-bit values below naturally aligned. */
 /*
  * arm64_relocate_new_kernel_size - Number of bytes to copy to the
  * control_code_page.
-- 
2.17.1