linux-kernel - [PATCH] kexec_core: Remove superfluous page offset handling in segment loading

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Message-ID: <20250910163116.49148-1-jbouron@amazon.com>
Date: Wed, 10 Sep 2025 09:31:16 -0700
From: Justinien Bouron <jbouron@...zon.com>
To: Andrew Morton <akpm@...ux-foundation.org>, Baoquan He <bhe@...hat.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>, Petr Mladek
	<pmladek@...e.com>, Mario Limonciello <mario.limonciello@....com>, "Marcos
 Paulo de Souza" <mpdesouza@...e.com>, Alexander Graf <graf@...zon.com>,
	Justinien Bouron <jbouron@...zon.com>, Steven Chen
	<chenste@...ux.microsoft.com>, Yan Zhao <yan.y.zhao@...el.com>,
	<kexec@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
CC: Gunnar Kudrjavets <gunnarku@...zon.com>
Subject: [PATCH] kexec_core: Remove superfluous page offset handling in segment loading

Kexec does not accept segments for which the destination address is not
page aligned. Therefore there is no need for page offset handling when
loading segments.

Signed-off-by: Justinien Bouron <jbouron@...zon.com>
Reviewed-by: Gunnar Kudrjavets <gunnarku@...zon.com>
---
 kernel/kexec_core.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 31203f0bacaf..7d4c9eebea79 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -761,9 +761,7 @@ static int kimage_load_cma_segment(struct kimage *image, int idx)
 	while (mbytes) {
 		size_t uchunk, mchunk;
 
-		ptr += maddr & ~PAGE_MASK;
-		mchunk = min_t(size_t, mbytes,
-				PAGE_SIZE - (maddr & ~PAGE_MASK));
+		mchunk = min_t(size_t, mbytes, PAGE_SIZE);
 		uchunk = min(ubytes, mchunk);
 
 		if (uchunk) {
@@ -815,6 +813,7 @@ static int kimage_load_normal_segment(struct kimage *image, int idx)
 	mbytes = segment->memsz;
 	maddr = segment->mem;
 
+
 	if (image->segment_cma[idx])
 		return kimage_load_cma_segment(image, idx);
 
@@ -840,9 +839,7 @@ static int kimage_load_normal_segment(struct kimage *image, int idx)
 		ptr = kmap_local_page(page);
 		/* Start with a clear page */
 		clear_page(ptr);
-		ptr += maddr & ~PAGE_MASK;
-		mchunk = min_t(size_t, mbytes,
-				PAGE_SIZE - (maddr & ~PAGE_MASK));
+		mchunk = min_t(size_t, mbytes, PAGE_SIZE);
 		uchunk = min(ubytes, mchunk);
 
 		if (uchunk) {
@@ -905,9 +902,7 @@ static int kimage_load_crash_segment(struct kimage *image, int idx)
 		}
 		arch_kexec_post_alloc_pages(page_address(page), 1, 0);
 		ptr = kmap_local_page(page);
-		ptr += maddr & ~PAGE_MASK;
-		mchunk = min_t(size_t, mbytes,
-				PAGE_SIZE - (maddr & ~PAGE_MASK));
+		mchunk = min_t(size_t, mbytes, PAGE_SIZE);
 		uchunk = min(ubytes, mchunk);
 		if (mchunk > uchunk) {
 			/* Zero the trailing part of the page */
-- 
2.43.0