| Message ID | 1434721406-25288-4-git-send-email-gerg@uclinux.org |
|---|---|
| State | New |
| Headers | show |
Le 19/06/2015 15:43, gerg@uclinux.org a écrit : > From: Greg Ungerer <gerg@uclinux.org> > > The action to potentially switch sp register is not occurring at the correct > point in the interrupt entry or exception exit sequences. > > For the interrupt entry case the sp on entry is used to create the stack > exception frame - but this may well be the user stack pointer, since we > haven't done the switch yet. Re-order the flow to switch the sp regs then > use the current sp to create the exception frame. > > For the return from exception case the code is unwinding the sp after > switching sp registers. But it should always unwind the supervisor sp > first, then carry out any required sp switch. > > Note that these problems don't effect operation unless the user sp bit is > set in the CACR register. Only a single sp is used in the default power up > state. Previously Linux only used this single sp mode. But modern versions > of Linux use the user sp mode now, so we need correct behavior for Linux > to work. > > Signed-off-by: Greg Ungerer <gerg@uclinux.org> > Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com> > --- > target-m68k/op_helper.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Hi Laurent, On 20/06/15 05:35, Laurent Vivier wrote: > Le 19/06/2015 15:43, gerg@uclinux.org a écrit : >> From: Greg Ungerer <gerg@uclinux.org> >> >> The action to potentially switch sp register is not occurring at the correct >> point in the interrupt entry or exception exit sequences. >> >> For the interrupt entry case the sp on entry is used to create the stack >> exception frame - but this may well be the user stack pointer, since we >> haven't done the switch yet. Re-order the flow to switch the sp regs then >> use the current sp to create the exception frame. >> >> For the return from exception case the code is unwinding the sp after >> switching sp registers. But it should always unwind the supervisor sp >> first, then carry out any required sp switch. >> >> Note that these problems don't effect operation unless the user sp bit is >> set in the CACR register. Only a single sp is used in the default power up >> state. Previously Linux only used this single sp mode. But modern versions >> of Linux use the user sp mode now, so we need correct behavior for Linux >> to work. >> >> Signed-off-by: Greg Ungerer <gerg@uclinux.org> >> Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com> >> --- >> target-m68k/op_helper.c | 7 +++---- >> 1 file changed, 3 insertions(+), 4 deletions(-) > > Reviewed-by: Laurent Vivier <laurent@vivier.eu> Thanks for the reviews. Regards Greg
diff --git a/target-m68k/op_helper.c b/target-m68k/op_helper.c index 06661f5..3a0d16f 100644 --- a/target-m68k/op_helper.c +++ b/target-m68k/op_helper.c @@ -63,8 +63,8 @@ static void do_rte(CPUM68KState *env) env->pc = cpu_ldl_kernel(env, sp + 4); sp |= (fmt >> 28) & 3; env->sr = fmt & 0xffff; - m68k_switch_sp(env); env->aregs[7] = sp + 8; + m68k_switch_sp(env); } static void do_interrupt_all(CPUM68KState *env, int is_hw) @@ -108,10 +108,7 @@ static void do_interrupt_all(CPUM68KState *env, int is_hw) vector = cs->exception_index << 2; - sp = env->aregs[7]; - fmt |= 0x40000000; - fmt |= (sp & 3) << 28; fmt |= vector << 16; fmt |= env->sr; @@ -121,6 +118,8 @@ static void do_interrupt_all(CPUM68KState *env, int is_hw) env->sr &= ~SR_M; } m68k_switch_sp(env); + sp = env->aregs[7]; + fmt |= (sp & 3) << 28; /* ??? This could cause MMU faults. */ sp &= ~3;