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From: Chris.Brandt@renesas.com (Chris Brandt)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 0/3] kallsyms: remove special handling for CONFIG_ARM
Date: Wed, 3 Feb 2016 13:33:13 +0000	[thread overview]
Message-ID: <HKXPR06MB05656F902E0E1FBBDBD713DC8AD00@HKXPR06MB0565.apcprd06.prod.outlook.com> (raw)
In-Reply-To: CAKv+Gu9VvskQ34w0niS+6AtF9hNcycfYDt_3Kp4T+WK8Vxf_dA@mail.gmail.com

On 2 Feb 2016, Chris Brandt wrote:
> I then applied the 3 patches and tried again and this time it booted
> up....almost.
> It looks like it makes it all the way up to when it is going to mount
> my rootfs, but then dies.


I did some debugging, and here's why I'm crashing.


If you look at my System.map file, you'll see that I've got 2 "__stubs_start" symbols.

One at 0x bf353edc, the other at 0x bf353ee0.

bf353edc T __stubs_start
bf353edc T _etext
bf353ee0 t __stubs_start
bf353ee4 t vector_rst
bf353f00 t vector_irq
bf353f80 t vector_dabt
bf354000 t vector_pabt
bf354080 t vector_und
bf354100 t vector_addrexcptn
bf354120 T vector_fiq
bf3541a0 T __stubs_end
bf3541a0 T __vectors_start
bf3541c0 t __mmap_switched
bf3541c0 T __vectors_end


So, when you get to early_trap_init(), it grabs the first __stubs_start for the memcpy:

	memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);


And when a printed out the destination, I get:

   Stubs at c09ff000 :00000000 BF006F20 EF9F0000 EA000064 etc...

Notice the first entry is 0....that's not right...and we know it's using that first __stubs_start symbol.


So, I hacked the code and put an offset of 4 like this:

	memcpy((void *)vectors + 0x1000, __stubs_start+4, __stubs_end - (__stubs_start+4));


And sure enough it booted fine.


So, why are there 2 __stubs_start symbols???
I haven't figured that one out yet.

And, I'm assuming you guys don't have 2 __stubs_start symbols either, correct?


Chris

  parent reply	other threads:[~2016-02-03 13:33 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-02 13:19 [PATCH 0/3] kallsyms: remove special handling for CONFIG_ARM Ard Biesheuvel
2016-02-02 13:19 ` [PATCH 1/3] ARM: move .vectors and .stubs sections back into the kernel VMA Ard Biesheuvel
2016-02-03  0:03   ` Russell King - ARM Linux
2016-02-03  0:20     ` Nicolas Pitre
2016-02-03  7:56     ` Ard Biesheuvel
2016-02-03  9:13       ` Russell King - ARM Linux
2016-02-03  9:16         ` Ard Biesheuvel
2016-02-08 16:39           ` Russell King - ARM Linux
2016-02-08 17:00             ` Russell King - ARM Linux
2016-02-08 17:01             ` Ard Biesheuvel
2016-02-02 13:19 ` [PATCH 2/3] kallsyms: remove special lower address limit for CONFIG_ARM Ard Biesheuvel
2016-02-02 13:19 ` [PATCH 3/3] kallsyms: remove --page-offset command line option Ard Biesheuvel
2016-02-03  0:05   ` Russell King - ARM Linux
2016-02-03  8:16     ` Ard Biesheuvel
2016-02-03  9:53       ` Maxime Coquelin
2016-02-02 17:51 ` [PATCH 0/3] kallsyms: remove special handling for CONFIG_ARM Nicolas Pitre
2016-02-02 18:59 ` Chris Brandt
2016-02-02 19:00   ` Ard Biesheuvel
2016-02-02 19:13     ` Chris Brandt
2016-02-03 13:33     ` Chris Brandt [this message]
2016-02-03 13:41       ` Ard Biesheuvel
2016-02-03 14:15         ` Chris Brandt
2016-02-03 14:17           ` Ard Biesheuvel
2016-02-03 20:01         ` Russell King - ARM Linux
2016-02-03 20:02           ` Ard Biesheuvel
2016-02-03 20:23             ` Nicolas Pitre
2016-02-03 20:30               ` Ard Biesheuvel
2016-02-03 20:41                 ` Ard Biesheuvel
2016-02-03 20:14 ` Linus Walleij

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