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From: David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>
To: Tom Turelinckx <tom-HiypchcOusz53ZRCpReHOg@public.gmane.org>
Cc: devicetree-compiler-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: bus error on sparc64 running type-preservation test
Date: Tue, 14 Apr 2020 16:25:34 +1000	[thread overview]
Message-ID: <20200414062534.GL48061@umbus.fritz.box> (raw)
In-Reply-To: <002001d611b0$c2dd7d20$48987760$@turelinckx.be>

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On Mon, Apr 13, 2020 at 06:29:52PM +0200, Tom Turelinckx wrote:
> I wrote:
> 
> > I have no idea how to fix this, but the following gdb backtrace (from v1.6.0) may help someone else:
> 
> With -O0:
> 
> Reading symbols from dtc...
> (gdb) r -I dts -O dts -o tests/type-preservation.dts.test.dts tests/type-preservation.dts
> Starting program: /build/device-tree-compiler-1.6.0/dtc -I dts -O dts -o tests/type-preservation.dts.test.dts tests/type-preservation.dts
> 
> Program received signal SIGBUS, Bus error.
> 0x0000010000017f2c in write_propval_int (f=0x1000012e300, p=0x100001348af "", len=4, width=4) at treesource.c:116
> 116                             fprintf(f, "0x%02"PRIx32, fdt32_to_cpu(*(const fdt32_t*)p));
> (gdb) bt
> #0  0x0000010000017f2c in write_propval_int (f=0x1000012e300, p=0x100001348af "", len=4, width=4) at treesource.c:116
> #1  0x0000010000018704 in write_propval (f=0x1000012e300, prop=0x100001348e0) at treesource.c:251
> #2  0x0000010000018b8c in write_tree_source_node (f=0x1000012e300, tree=0x10000134960, level=3) at treesource.c:310
> #3  0x0000010000018c04 in write_tree_source_node (f=0x1000012e300, tree=0x10000134a30, level=2) at treesource.c:314
> #4  0x0000010000018c04 in write_tree_source_node (f=0x1000012e300, tree=0x10000134b20, level=1) at treesource.c:314
> #5  0x0000010000018c04 in write_tree_source_node (f=0x1000012e300, tree=0x10000134c10, level=0) at treesource.c:314
> #6  0x0000010000018e28 in dt_to_source (f=0x1000012e300, dti=0x100001325c0) at treesource.c:344
> #7  0x0000010000005f1c in main (argc=8, argv=0x7fefffff528) at dtc.c:351

Yeah, it definitely looks like an alignment problem.  The 'p'
parameter to write_propval_int() is not 4-byte aligned, but width ==
4, which means it will attempt to read from p as a 32-bit integer
pointer.

Some grepping also suggests several other places in dtc which could
suffer from the same problem, though I suspect they're less likely to
trigger.

I've just merged and pushed a change which I think will fix this to
the master branch.  Could you build and test that please?

If you can make a minimal testcase which triggers this problem and
submit it as an addition to the dtc testsuite, that would be terrific.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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  reply	other threads:[~2020-04-14  6:25 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-13 16:09 bus error on sparc64 running type-preservation test Tom Turelinckx
2020-04-13 16:29 ` Tom Turelinckx
2020-04-14  6:25   ` David Gibson [this message]
     [not found]     ` <20200414062534.GL48061-K0bRW+63XPQe6aEkudXLsA@public.gmane.org>
2020-04-14 16:34       ` Tom Turelinckx
     [not found]         ` <4c0be4b4-7f6e-4612-af7b-dfffb400597a-jFIJ+Wc5/Vo7lZ9V/NTDHw@public.gmane.org>
2020-04-21  3:22           ` David Gibson

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