Re: [Qemu-devel] [PATCH] ARM (Thumb) read from R15
On Saturday 30 June 2007 04:19, Paul Brook wrote: QEMU does not set the Thumb bit when reading from R15 in Thumb mode. Neither does real hardware. You are, unsurprisingly, right. The problem seems to be a different one. Quoting the ARM on pop pc: In ARM architecture 5 and above, bit[0] of the loaded value determines whether execution continues after this branch in ARM state or in Thumb state[...] In T variants of architecture version 4, bit[0] of the loaded value is ignored and execution continues in Thumb state[...] My code is supposed to run on a 4T. I guess I'll have to implement an ARM_FEATURE_THUMB1. CU Uli -- SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
Re: [Qemu-devel] [PATCH] ARM (Thumb) read from R15
On Monday 02 July 2007, Ulrich Hecht wrote: On Saturday 30 June 2007 04:19, Paul Brook wrote: QEMU does not set the Thumb bit when reading from R15 in Thumb mode. Neither does real hardware. You are, unsurprisingly, right. The problem seems to be a different one. Quoting the ARM on pop pc: In ARM architecture 5 and above, bit[0] of the loaded value determines whether execution continues after this branch in ARM state or in Thumb state[...] In T variants of architecture version 4, bit[0] of the loaded value is ignored and execution continues in Thumb state[...] My code is supposed to run on a 4T. I guess I'll have to implement an ARM_FEATURE_THUMB1. As you have found out, qemu doesn't currently emulate v4t. There are a couple of other instructions that should be disabled (blx) if you do this. Paul
Re: [Qemu-devel] [PATCH] ARM (Thumb) read from R15
QEMU does not set the Thumb bit when reading from R15 in Thumb mode. Neither does real hardware. Paul
[Qemu-devel] [PATCH] ARM (Thumb) read from R15
Hi!
QEMU does not set the Thumb bit when reading from R15 in Thumb mode.
Here's the fix:
Index: target-arm/translate.c
===
RCS file: /sources/qemu/qemu/target-arm/translate.c,v
retrieving revision 1.53
diff -u -r1.53 translate.c
--- target-arm/translate.c 11 Jun 2007 18:59:35 - 1.53
+++ target-arm/translate.c 28 Jun 2007 14:29:15 -
@@ -307,7 +307,7 @@
if (reg == 15) {
/* normaly, since we updated PC, we need only to add one insn */
if (s-thumb)
-val = (long)s-pc + 2;
+val = (long)s-pc + 3;
else
val = (long)s-pc + 4;
gen_op_movl_TN_im[t](val);
CU
Uli
--
SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
Re: [Qemu-devel] [PATCH] ARM (Thumb) read from R15
On Thursday 28 June 2007 16:31, Ulrich Hecht wrote: QEMU does not set the Thumb bit when reading from R15 in Thumb mode. Here's the fix: Maybe not; this seems to break some cases ... :( CU Uli -- SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
Re: [Qemu-devel] [PATCH] ARM (Thumb) read from R15
On Thursday 28 June 2007 17:30, Ulrich Hecht wrote:
On Thursday 28 June 2007 16:31, Ulrich Hecht wrote:
QEMU does not set the Thumb bit when reading from R15 in Thumb mode.
Here's the fix:
Maybe not; this seems to break some cases ... :(
This works in all my cases, although I am not sure if it is correct:
Index: target-arm/translate.c
===
RCS file: /sources/qemu/qemu/target-arm/translate.c,v
retrieving revision 1.53
diff -u -r1.53 translate.c
--- target-arm/translate.c 11 Jun 2007 18:59:35 - 1.53
+++ target-arm/translate.c 28 Jun 2007 15:48:59 -
@@ -307,7 +307,7 @@
if (reg == 15) {
/* normaly, since we updated PC, we need only to add one insn */
if (s-thumb)
-val = (long)s-pc + 2;
+val = (long)s-pc + 3;
else
val = (long)s-pc + 4;
gen_op_movl_TN_im[t](val);
@@ -3062,7 +3062,10 @@
gen_op_movl_T1_im(val);
gen_movl_reg_T1(s, 14);
}
-gen_movl_T0_reg(s, rm);
+if (rm == 15)
+ gen_op_movl_T0_im(s-pc + 2);
+else
+ gen_movl_T0_reg(s, rm);
gen_bx(s);
break;
}
CU
Uli
--
SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
