Public bug reported:
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.
** Affects: qemu
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1248168
Title:
MIPS, self-modifying code and uncached memory
Status in QEMU:
New
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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