> From: Jan Kiszka [mailto:jan.kis...@siemens.com] > On 2014-10-22 13:38, Pavel Dovgalyuk wrote: > > This patch fixes instructions counting when execution is stopped on > > breakpoint (e.g. set from gdb). Without a patch extra instruction is > > translated > > and icount is incremented by invalid value (which equals to number of > > executed instructions + 1). > > > > Signed-off-by: Pavel Dovgalyuk <pavel.dovga...@ispras.ru> > > --- > > target-i386/translate.c | 3 ++- > > 1 files changed, 2 insertions(+), 1 deletions(-) > > > > diff --git a/target-i386/translate.c b/target-i386/translate.c > > index 1284173..193cf9f 100644 > > --- a/target-i386/translate.c > > +++ b/target-i386/translate.c > > @@ -8000,7 +8000,7 @@ static inline void > > gen_intermediate_code_internal(X86CPU *cpu, > > if (bp->pc == pc_ptr && > > !((bp->flags & BP_CPU) && (tb->flags & HF_RF_MASK))) { > > gen_debug(dc, pc_ptr - dc->cs_base); > > - break; > > + goto done_generating; > > } > > } > > } > > @@ -8049,6 +8049,7 @@ static inline void > > gen_intermediate_code_internal(X86CPU *cpu, > > break; > > } > > } > > +done_generating: > > if (tb->cflags & CF_LAST_IO) > > gen_io_end(); > > gen_tb_end(tb, num_insns); > > > > > > > > Didn't looked into why, just bisected that this patch breaks at least > certain guest-originated break- or watchpoints in TCG mode. Can be > triggered by booting a Linux kernel with kgdb self-tests enabled. The > result is some false reporting of a host-originated debug stop to > gdb_set_stop_cpu while gdbserver_state is NULL -> SEGV.
It seems that kernel sets some hardware breakpoints and QEMU tries to process them with GDB stub. Modifying gdb_set_stop_cpu should help: diff --git a/gdbstub.c b/gdbstub.c index e4a1a79..e8ef546 100644 --- a/gdbstub.c +++ b/gdbstub.c @@ -1202,8 +1202,10 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf) void gdb_set_stop_cpu(CPUState *cpu) { - gdbserver_state->c_cpu = cpu; - gdbserver_state->g_cpu = cpu; + if (gdbserver_state) { + gdbserver_state->c_cpu = cpu; + gdbserver_state->g_cpu = cpu; + } } #ifndef CONFIG_USER_ONLY Pavel Dovgalyuk