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[Qemu-devel] [PATCH] gdbstub: allow byte swapping for reading/writing re
From: |
Thomas Falcon |
Subject: |
[Qemu-devel] [PATCH] gdbstub: allow byte swapping for reading/writing registers |
Date: |
Tue, 14 Jan 2014 16:06:10 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131028 Thunderbird/17.0.10 |
This patch allows registers to be properly read from and written to
when using the gdbstub to debug a ppc guest running in little
endian mode. It accomplishes this goal by byte swapping the values of
any registers only if the MSR:LE value is set and if the host machine
is big endian.
Signed-off-by: Thomas Falcon<address@hidden>
---
target-ppc/gdbstub.c | 50 ++++++++++++++++++++++++++++++++------------------
1 file changed, 32 insertions(+), 18 deletions(-)
diff --git a/target-ppc/gdbstub.c b/target-ppc/gdbstub.c
index 1c91090..eba501a 100644
--- a/target-ppc/gdbstub.c
+++ b/target-ppc/gdbstub.c
@@ -21,6 +21,19 @@
#include "qemu-common.h"
#include "exec/gdbstub.h"
+/* The following macros are used to ensure the correct
+ * transfer of registers between a little endian ppc target
+ * and a big endian host by checking the LE bit in the Machine State Register
+ */
+
+#define end_swap64(x) (msr_le && HOST_WORDS_BIGENDIAN) ? bswap64(x) : x
+#define end_swap32(x) (msr_le && HOST_WORDS_BIGENDIAN) ? bswap32(x) : x
+#if TARGET_LONG_BITS == 64
+#define end_swapl(x) end_swap64(x)
+#else
+#define end_swapl(x) end_swap32(x)
+#endif
+
/* Old gdb always expects FP registers. Newer (xml-aware) gdb only
* expects whatever the target description contains. Due to a
* historical mishap the FP registers appear in between core integer
@@ -35,20 +48,20 @@ int ppc_cpu_gdb_read_register(CPUState *cs, uint8_t
*mem_buf, int n)
if (n < 32) {
/* gprs */
- return gdb_get_regl(mem_buf, env->gpr[n]);
+ return gdb_get_regl(mem_buf, end_swapl(env->gpr[n]));
} else if (n < 64) {
/* fprs */
if (gdb_has_xml) {
return 0;
}
- stfq_p(mem_buf, env->fpr[n-32]);
+ stfq_p(mem_buf, end_swapl(env->fpr[n-32]));
return 8;
} else {
switch (n) {
case 64:
- return gdb_get_regl(mem_buf, env->nip);
+ return gdb_get_regl(mem_buf, end_swapl(env->nip));
case 65:
- return gdb_get_regl(mem_buf, env->msr);
+ return gdb_get_regl(mem_buf, end_swapl(env->msr));
case 66:
{
uint32_t cr = 0;
@@ -56,20 +69,20 @@ int ppc_cpu_gdb_read_register(CPUState *cs, uint8_t
*mem_buf, int n)
for (i = 0; i < 8; i++) {
cr |= env->crf[i] << (32 - ((i + 1) * 4));
}
- return gdb_get_reg32(mem_buf, cr);
+ return gdb_get_reg32(mem_buf, end_swap32(cr));
}
case 67:
- return gdb_get_regl(mem_buf, env->lr);
+ return gdb_get_regl(mem_buf, end_swapl(env->lr));
case 68:
- return gdb_get_regl(mem_buf, env->ctr);
+ return gdb_get_regl(mem_buf, end_swapl(env->ctr));
case 69:
- return gdb_get_regl(mem_buf, env->xer);
+ return gdb_get_regl(mem_buf, end_swapl(env->xer));
case 70:
{
if (gdb_has_xml) {
return 0;
}
- return gdb_get_reg32(mem_buf, env->fpscr);
+ return gdb_get_reg32(mem_buf, end_swap32(env->fpscr));
}
}
}
@@ -83,47 +96,48 @@ int ppc_cpu_gdb_write_register(CPUState *cs, uint8_t
*mem_buf, int n)
if (n < 32) {
/* gprs */
- env->gpr[n] = ldtul_p(mem_buf);
+ env->gpr[n] = end_swapl(ldtul_p(mem_buf));
return sizeof(target_ulong);
} else if (n < 64) {
/* fprs */
if (gdb_has_xml) {
return 0;
}
- env->fpr[n-32] = ldfq_p(mem_buf);
+ env->fpr[n-32] = end_swapl(ldfq_p(mem_buf));
return 8;
} else {
switch (n) {
case 64:
- env->nip = ldtul_p(mem_buf);
+ env->nip = end_swapl(ldtul_p(mem_buf));
return sizeof(target_ulong);
case 65:
- ppc_store_msr(env, ldtul_p(mem_buf));
+ ppc_store_msr(env, end_swapl(ldtul_p(mem_buf)));
return sizeof(target_ulong);
case 66:
{
uint32_t cr = ldl_p(mem_buf);
int i;
for (i = 0; i < 8; i++) {
- env->crf[i] = (cr >> (32 - ((i + 1) * 4))) & 0xF;
+ env->crf[i] = end_swap32((cr >> (32 -
+ ((i + 1) * 4))) & 0xF);
}
return 4;
}
case 67:
- env->lr = ldtul_p(mem_buf);
+ env->lr = end_swapl(ldtul_p(mem_buf));
return sizeof(target_ulong);
case 68:
- env->ctr = ldtul_p(mem_buf);
+ env->ctr = end_swapl(ldtul_p(mem_buf));
return sizeof(target_ulong);
case 69:
- env->xer = ldtul_p(mem_buf);
+ env->xer = end_swapl(ldtul_p(mem_buf));
return sizeof(target_ulong);
case 70:
/* fpscr */
if (gdb_has_xml) {
return 0;
}
- store_fpscr(env, ldtul_p(mem_buf), 0xffffffff);
+ store_fpscr(env, end_swapl(ldtul_p(mem_buf)), 0xffffffff);
return sizeof(target_ulong);
}
}
-- 1.8.3.1
- [Qemu-devel] [PATCH] gdbstub: allow byte swapping for reading/writing registers,
Thomas Falcon <=