linux-kernel - [PATCH 1/2] x86: early_memremap exact size of struct setup

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Message-Id: <1420628150-16872-1-git-send-email-chaowang@redhat.com>
Date:	Wed,  7 Jan 2015 18:55:48 +0800
From:	WANG Chao <chaowang@...hat.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	x86@...nel.org (maintainer:X86 ARCHITECTURE...),
	Matt Fleming <matt.fleming@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Borislav Petkov <bp@...e.de>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	"Bryan O'Donoghue" <pure.logic@...us-software.ie>,
	linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE...)
Subject: [PATCH 1/2] x86: early_memremap exact size of struct setup_data

When early remapping setup_data, we can remap the structure alone, use
sizeof(struct setup_data). No need to remap a larger area, we never
access setup_data->data at that point.

Signed-off-by: WANG Chao <chaowang@...hat.com>
---
 arch/x86/kernel/setup.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index ab4734e..c4648ada 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -431,15 +431,13 @@ static void __init parse_setup_data(void)
 
 	pa_data = boot_params.hdr.setup_data;
 	while (pa_data) {
-		u32 data_len, map_len, data_type;
+		u32 data_len, data_type;
 
-		map_len = max(PAGE_SIZE - (pa_data & ~PAGE_MASK),
-			      (u64)sizeof(struct setup_data));
-		data = early_memremap(pa_data, map_len);
+		data = early_memremap(pa_data, sizeof(*data));
 		data_len = data->len + sizeof(struct setup_data);
 		data_type = data->type;
 		pa_next = data->next;
-		early_iounmap(data, map_len);
+		early_iounmap(data, sizeof(*data));
 
 		switch (data_type) {
 		case SETUP_E820_EXT:
-- 
2.1.0

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