linux-kernel - [PATCH] arm: remove [_text, _stext) from kernel code resource

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Date:   Fri, 3 Dec 2021 22:14:16 +0800
From:   Mark-PK Tsai <mark-pk.tsai@...iatek.com>
To:     <linux@...linux.org.uk>, <matthias.bgg@...il.com>,
        <rmk+kernel@...linux.org.uk>
CC:     <arnd@...db.de>, <akpm@...ux-foundation.org>, <linux@...ck-us.net>,
        <rppt@...nel.org>, <wangkefeng.wang@...wei.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <yj.chiang@...iatek.com>,
        <mark-pk.tsai@...iatek.com>
Subject: [PATCH] arm: remove [_text, _stext) from kernel code resource

Remove the [_text, _stext) from Kernel Code.
Although there are some startup code in head.text, they
are freed to the buddy system after kernel boot.

And we have memory protection mechanism use this
which have false alarm when some other IPs doing dma
if the dma page frame is in the [_text, _stext).

Below are my iomem resource and reserved memory information:
console:/ # grep Kernel /proc/iomem
  20208000-219fffff : Kernel code
  21b00000-21c2e76f : Kernel data

console:/ # cat /sys/kernel/debug/memblock/reserved
0: 0x20201000..0x20207fff
1: 0x20300000..0x21c2e76f

Signed-off-by: Mark-PK Tsai <mark-pk.tsai@...iatek.com>
---
 arch/arm/kernel/setup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 284a80c0b6e1..85ffc9501e38 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -851,7 +851,7 @@ static void __init request_standard_resources(const struct machine_desc *mdesc)
 	struct resource *res;
 	u64 i;
 
-	kernel_code.start   = virt_to_phys(_text);
+	kernel_code.start   = virt_to_phys(_stext);
 	kernel_code.end     = virt_to_phys(__init_begin - 1);
 	kernel_data.start   = virt_to_phys(_sdata);
 	kernel_data.end     = virt_to_phys(_end - 1);
-- 
2.18.0