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[Qemu-devel] icount and unaligned IO accesses
From: |
Edgar E. Iglesias |
Subject: |
[Qemu-devel] icount and unaligned IO accesses |
Date: |
Tue, 26 Jan 2010 14:16:46 +0100 |
User-agent: |
Mutt/1.5.20 (2009-06-14) |
Hi,
While emulating a small MMU-less CRIS system I ran into an -icount
related problem. Without icount the emulation runs fine, with icount
I get stuff like:
qemu: fatal: cpu_io_recompile: could not find TB for pc=0x4be7fd
IIUC, there is a recursion bug in the slow_ldx() calls that ends
up clobbering retaddr. Later if the TB is aborted on the IO
access, the code to map retaddr into guest PC fails to even find
a TB because retaddr wrongly points to slow_ldx().
It seems to me like we simply shouldn't be touching retaddr
in slow_ldx().
The following patch fixes the problem for me. slow_st() was
AFAICS already OK.
Comments?
Cheers
commit a4a31d3039e82b7550933e3d8e1f4c6e9a7f8529
Author: Edgar E. Iglesias <address@hidden>
Date: Tue Jan 26 13:55:55 2010 +0100
softmmu: Dont clobber retaddr in slow_ldx().
When splitting up unaligned IO accesses, ld calls slow_ld which was
clobbering retaddr.
AFAIK the problem only shows up when running emulations with -icount
that may abort TB execution on IO accesses.
Signed-off-by: Edgar E. Iglesias <address@hidden>
diff --git a/softmmu_template.h b/softmmu_template.h
index abf18d2..9185c32 100644
--- a/softmmu_template.h
+++ b/softmmu_template.h
@@ -161,7 +161,6 @@ static DATA_TYPE glue(glue(slow_ld, SUFFIX),
MMUSUFFIX)(target_ulong addr,
/* IO access */
if ((addr & (DATA_SIZE - 1)) != 0)
goto do_unaligned_access;
- retaddr = GETPC();
addend = env->iotlb[mmu_idx][index];
res = glue(io_read, SUFFIX)(addend, addr, retaddr);
} else if (((addr & ~TARGET_PAGE_MASK) + DATA_SIZE - 1) >=
TARGET_PAGE_SIZE) {
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