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From: Thomas Huth <1248168@bugs.launchpad.net>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] [Bug 1248168] Re: MIPS, self-modifying code and uncached memory
Date: Mon, 23 Jan 2017 17:48:35 -0000	[thread overview]
Message-ID: <20170123174837.14023.51031.launchpad@soybean.canonical.com> (raw)
In-Reply-To: 20131105124713.24131.16100.malonedeb@gac.canonical.com

** Changed in: qemu
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1248168

Title:
  MIPS, self-modifying code and uncached memory

Status in QEMU:
  Incomplete

Bug description:
  Self-modifying code does not work properly in MIPS in uncached and
  unmapped kseg1 memory region.

  For example, when running this code I get unexpected behavior:

     0:	e3000010 	b	0x390
     4:	00000000 	nop
  	...
   380:	00701f40 	mfc0	ra,c0_epc
   384:	0400e0bb 	swr	zero,4(ra)
   388:	18000042 	eret
   38c:	00000000 	nop
   390:	25500000 	move	t2,zero
   394:	02000b34 	li	t3,0x2
   398:	23504b01 	subu	t2,t2,t3
   39c:	e9003c0b 	j	0xcf003a4
   3a0:	0a004a21 	addi	t2,t2,10
   3a4:	ffff0010 	b	0x3a4
   3a8:	00000000 	nop
   3ac:	00000000 	nop

    I expect that swr instruction in line 384 would change `addi	t2,t2,1`0 to `nop`
  This should work because no cache is used for this memory region.

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  parent reply	other threads:[~2017-01-23 18:05 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-05 12:47 [Qemu-devel] [Bug 1248168] [NEW] MIPS, self-modifying code and uncached memory Nikita Kanunnikov
2013-11-05 16:24 ` Antony Pavlov
2013-11-06 19:42 ` [Qemu-devel] [Bug 1248168] " Petar Jovanovic
2017-01-23 17:48 ` Thomas Huth [this message]
2017-03-25  4:17 ` Launchpad Bug Tracker

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