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* [PATCH] arm: export memblock_reserve()d regions via /proc/iomem
@ 2019-09-21 13:02 Yu Chen
  2019-09-21 14:51 ` Russell King - ARM Linux admin
  2019-09-22  8:36 ` kbuild test robot
  0 siblings, 2 replies; 5+ messages in thread
From: Yu Chen @ 2019-09-21 13:02 UTC (permalink / raw)
  To: rmk+kernel, linux; +Cc: linux-arm-kernel, linux-kernel, yu.chen3

From: Yu Chen <yu.chen3@zte.com.cn>

memblock reserved regions are not reported via /proc/iomem on ARM, kexec's
user-space doesn't know about memblock_reserve()d regions and thus
possible for kexec to overwrite with the new kernel or initrd.

[    0.000000] Booting Linux on physical CPU 0xf00
[    0.000000] Linux version 4.9.115-rt93-dirty (yuchen@localhost.localdomain) (gcc version 6.2.0 (ZTE Embsys-TSP V3.07.2
0) ) #62 SMP PREEMPT Fri Sep 20 10:39:29 CST 2019
[    0.000000] CPU: ARMv7 Processor [410fc075] revision 5 (ARMv7), cr=30c5387d
[    0.000000] CPU: div instructions available: patching division code
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[    0.000000] OF: fdt:Machine model: LS1021A TWR Board
[    0.000000] INITRD: 0x80f7f000+0x03695e40 overlaps in-use memory region - disabling initrd

Signed-off-by: Yu Chen <yu.chen3@zte.com.cn>
Reviewed-by: Junhua Huang <huang.junhua@zte.com.cn>
---
 arch/arm/kernel/setup.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index d0a464e..606d1ac 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -911,6 +911,34 @@ static void __init request_standard_resources(const struct machine_desc *mdesc)
 		request_resource(&ioport_resource, &lp2);
 }
 
+static int __init reserve_memblock_reserved_regions(void)
+{
+	u64 i, j;
+
+	for (i = 0; i < num_standard_resources; ++i) {
+		struct resource *mem = &standard_resources[i];
+		phys_addr_t r_start, r_end, mem_size = resource_size(mem);
+
+		if (!memblock_is_region_reserved(mem->start, mem_size))
+			continue;
+
+		for_each_reserved_mem_region(j, &r_start, &r_end) {
+			resource_size_t start, end;
+
+			start = max(PFN_PHYS(PFN_DOWN(r_start)), mem->start);
+			end = min(PFN_PHYS(PFN_UP(r_end)) - 1, mem->end);
+
+			if (start > mem->end || end < mem->start)
+				continue;
+
+			reserve_region_with_split(mem, start, end, "reserved");
+		}
+	}
+
+	return 0;
+}
+arch_initcall(reserve_memblock_reserved_regions);
+
 #if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_DUMMY_CONSOLE) || \
     defined(CONFIG_EFI)
 struct screen_info screen_info = {
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 5+ messages in thread
* Re: [PATCH] arm: export memblock_reserve()d regions via /proc/iomem
@ 2019-09-23 15:42 Yu Chen
  2019-09-23 16:14 ` Russell King - ARM Linux admin
  0 siblings, 1 reply; 5+ messages in thread
From: Yu Chen @ 2019-09-23 15:42 UTC (permalink / raw)
  To: linux; +Cc: linux-arm-kernel, linux-kernel, yu.chen3

From: Yu Chen <yu.chen3@zte.com.cn>

On Sat, 21 Sep 2019 15:51:38, Russell King - ARM Linux admin wrote:
> On Sat, Sep 21, 2019 at 09:02:49PM +0800, Yu Chen wrote:
> > From: Yu Chen <yu.chen3@zte.com.cn> 
> >  
> > memblock reserved regions are not reported via /proc/iomem on ARM, kexec's
> > user-space doesn't know about memblock_reserve()d regions and thus
> > possible for kexec to overwrite with the new kernel or initrd.
> 
> Many reserved regions come from the kernel allocating memory during
> boot.  We don't want to prevent kexec re-using those regions.
> 
> > [    0.000000] Booting Linux on physical CPU 0xf00
> > [    0.000000] Linux version 4.9.115-rt93-dirty (yuchen@localhost.localdomain) (gcc version 6.2.0 (ZTE Embsys-TSP V3.07.2
> > 0) ) #62 SMP PREEMPT Fri Sep 20 10:39:29 CST 2019
> > [    0.000000] CPU: ARMv7 Processor [410fc075] revision 5 (ARMv7), cr=30c5387d
> > [    0.000000] CPU: div instructions available: patching division code
> > [    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
> > [    0.000000] OF: fdt:Machine model: LS1021A TWR Board
> > [    0.000000] INITRD: 0x80f7f000+0x03695e40 overlaps in-use memory region - disabling initrd
> 
> Is the overlapping region one that is marked as reserved in DT?

the overlapping region is not reserved in DT.

> Where is the reserved region that overlaps the initrd coming from?

I found the reserved region that overlaps the initrd is kernel code & data, 
with memblock=debug cmdline start new kerne:

/ # kexec -l uImage-ls1021a --ramdisk=ramdisk-ls1021a --dtb=fdt --append="root=/
dev/ram0 rw console=ttyS0,115200 earlyprintk memblock=debug" -d
Try gzip decompression.
Try LZMA decompression.
lzma_decompress_file: read on uImage-ls1021a of 65536 bytes failed
kernel: 0xb6c71008 kernel_size: 0x317ab8
MEMORY RANGES
0000000080000000-00000000bfffffff (0)
0000000080003000-0000000080007fff (1)
0000000080e00000-0000000080ffffff (1)
00000000810c45a4-00000000810c4fff (1)
0000000081ac4000-0000000085159fff (1)
000000008515a000-000000008515ffff (1)
0000000088000000-000000008b695fff (1)
000000008f000000-000000008f004fff (1)
00000000af709000-00000000af7eafff (1)
00000000af7ed000-00000000afffbfff (1)
00000000afffc000-00000000afffcfff (1)
00000000afffd000-00000000afffffff (1)
00000000bc000000-00000000bfffffff (1)
zImage header: 0x016f2818 0x00000000 0x00317a78
zImage size 0x317a78, file size 0x317a78
kexec_load: entry = 0x80008000 flags = 0x280000
nr_segments = 3
segment[0].buf   = 0xb6c71048
segment[0].bufsz = 0x317a78
segment[0].mem   = 0x80008000
segment[0].memsz = 0x318000
segment[1].buf   = 0xb35db048
segment[1].bufsz = 0x3695e40
segment[1].mem   = 0x80f7f000
segment[1].memsz = 0x3696000
segment[2].buf   = 0x100b108
segment[2].bufsz = 0x5090
segment[2].mem   = 0x84615000
segment[2].memsz = 0x6000
/ # kexec -e
[  126.583598] kexec_core: Starting new kernel
[  126.587815] Disabling non-boot CPUs ...
[  126.626917] CPU1: shutdown
[  126.656344] Retrying again to check for CPU kill
[  126.660947] CPU1 killed.
[  126.687585] Bye!
[    0.000000] Booting Linux on physical CPU 0xf00
[    0.000000] Linux version 4.9.115-rt93-CGEL-V6.02.10.R4-dirty (yuchen@localhost.localdomain) (gcc version 6.2.0 (ZTE Embsys-TSP V3.07.20) ) #62 SMP PREEMPT Fri Sep 20 10:39:29 CST 2019
[    0.000000] CPU: ARMv7 Processor [410fc075] revision 5 (ARMv7), cr=30c5387d
[    0.000000] CPU: div instructions available: patching division code
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[    0.000000] OF: fdt:Machine model: LS1021A TWR Board
[    0.000000] memblock_reserve: [0x00000080200000-0x000000810c45a3] flags 0x0 arm_memblock_init+0x44/0x23c
[    0.000000] INITRD: 0x80f7f000+0x03695e40 overlaps in-use memory region - disabling initrd
[    0.000000] memblock_reserve: [0x00000080003000-0x00000080007fff] flags 0x0 arm_mm_memblock_reserve+0x2c/0x30
[    0.000000] memblock_reserve: [0x00000084615000-0x0000008461a08f] flags 0x0 early_init_dt_reserve_memory_arch+0x24/0x28
[    0.000000] memblock_reserve: [0x0000008f000000-0x0000008f004fff] flags 0x0 early_init_dt_reserve_memory_arch+0x24/0x28
[    0.000000] memblock_reserve: [0x00000088000040-0x0000008b695e3f] flags 0x0 early_init_dt_reserve_memory_arch+0x24/0x28
[    0.000000] memblock_reserve: [0x000000bc000000-0x000000bfffffff] flags 0x0 memblock_alloc_range_nid+0x78/0x90
 ... 
 ---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(1,0)

this overlay region is [0x00000080200000-0x000000810c45a3]

Corresponding kernel source code:
264 void __init arm_memblock_init(const struct machine_desc *mdesc)
265 {
266         /* Register the kernel text, kernel data and initrd with memblock. */
267         memblock_reserve(__pa(KERNEL_START), KERNEL_END - KERNEL_START);

> 
> Thanks.
> 
> --  
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
> According to speedtest.net: 11.9Mbps down 500kbps up

And Sorry, I sent the wrong arm64 patch. if possible, I will resend the second version of the patch.

Yu Chen


^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-09-23 16:14 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-09-21 13:02 [PATCH] arm: export memblock_reserve()d regions via /proc/iomem Yu Chen
2019-09-21 14:51 ` Russell King - ARM Linux admin
2019-09-22  8:36 ` kbuild test robot
2019-09-23 15:42 Yu Chen
2019-09-23 16:14 ` Russell King - ARM Linux admin

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