[PATCH v2] gdbstub: Fix segment fault for i386 target

[Changbin Du <changbin.du@gmail.com>]

With GByteArray, we should pass the object itself but not to plus an offset.

gdb log:
Thread 1 "qemu-system-x86" received signal SIGSEGV, Segmentation fault.
__memmove_avx_unaligned_erms () at ../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:384
384	../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S: No such file or directory.

Fixes: a010bdbe71 ("gdbstub: extend GByteArray to read register helpers")
Signed-off-by: Changbin Du <changbin.du@gmail.com>

---
v2: remove m68k fix since it's already queued.
---
 target/i386/gdbstub.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/i386/gdbstub.c b/target/i386/gdbstub.c
index f3d23b614e..b98a99500a 100644
--- a/target/i386/gdbstub.c
+++ b/target/i386/gdbstub.c
@@ -106,7 +106,7 @@ int x86_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
     } else if (n >= IDX_FP_REGS && n < IDX_FP_REGS + 8) {
         floatx80 *fp = (floatx80 *) &env->fpregs[n - IDX_FP_REGS];
         int len = gdb_get_reg64(mem_buf, cpu_to_le64(fp->low));
-        len += gdb_get_reg16(mem_buf + len, cpu_to_le16(fp->high));
+        len += gdb_get_reg16(mem_buf, cpu_to_le16(fp->high));
         return len;
     } else if (n >= IDX_XMM_REGS && n < IDX_XMM_REGS + CPU_NB_REGS) {
         n -= IDX_XMM_REGS;
-- 
2.25.1