| Message ID | 20170713032548.451-1-matthew.brown.dev@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On 13/07/17 13:25, Matt Brown wrote: > @@ -1049,6 +1066,13 @@ int analyse_instr(struct instruction_op *op, struct pt_regs *regs, > do_cmp_unsigned(regs, val, val2, rd >> 2); > goto instr_done; > > + case 19173952: /* cmpb */ This looks wrong and should never trigger, given that the switch statement is comparing against ((instr >> 1) & 0x3ff). How did you get this value?
On Thu, Jul 13, 2017 at 01:51:30PM +1000, Andrew Donnellan wrote: > On 13/07/17 13:25, Matt Brown wrote: > >@@ -1049,6 +1066,13 @@ int analyse_instr(struct instruction_op *op, struct > >pt_regs *regs, > > do_cmp_unsigned(regs, val, val2, rd >> 2); > > goto instr_done; > > > >+ case 19173952: /* cmpb */ > > This looks wrong and should never trigger, given that the switch > statement is comparing against ((instr >> 1) & 0x3ff). > > How did you get this value? The correct number is 508, and 19173952 = 37744*508. How to get 37744 is a mystery though :-) Segher
On Thu, Jul 13, 2017 at 01:25:44PM +1000, Matt Brown wrote: > +static nokprobe_inline void do_cmpb(struct pt_regs *regs, unsigned long v1, > + unsigned long v2, int rd) > +{ > + unsigned long out_val, mask; > + int i; > + > + out_val = 0; > + for (i = 0; i < 8; i++) { > + mask = 0xff << (i * 8); 0xffUL ? > + > + if ((v1 & mask) == (v2 & mask)) > + out_val |= mask; > + } > + > + regs->gpr[rd] = out_val; > +} Segher
On Thu, Jul 13, 2017 at 01:43:53AM -0500, Segher Boessenkool wrote: > On Thu, Jul 13, 2017 at 01:51:30PM +1000, Andrew Donnellan wrote: > > On 13/07/17 13:25, Matt Brown wrote: > > >@@ -1049,6 +1066,13 @@ int analyse_instr(struct instruction_op *op, struct > > >pt_regs *regs, > > > do_cmp_unsigned(regs, val, val2, rd >> 2); > > > goto instr_done; > > > > > >+ case 19173952: /* cmpb */ > > > > This looks wrong and should never trigger, given that the switch > > statement is comparing against ((instr >> 1) & 0x3ff). > > > > How did you get this value? > > The correct number is 508, and 19173952 = 37744*508. How to get > 37744 is a mystery though :-) Ah. Take the binary representation of 508, and interpret that as if it were octal :-) Those pesky meddling leading zeroes! Segher
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c index 33117f8..f3e9ba8 100644 --- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -596,6 +596,23 @@ static nokprobe_inline void do_cmp_unsigned(struct pt_regs *regs, unsigned long regs->ccr = (regs->ccr & ~(0xf << shift)) | (crval << shift); } +static nokprobe_inline void do_cmpb(struct pt_regs *regs, unsigned long v1, + unsigned long v2, int rd) +{ + unsigned long out_val, mask; + int i; + + out_val = 0; + for (i = 0; i < 8; i++) { + mask = 0xff << (i * 8); + + if ((v1 & mask) == (v2 & mask)) + out_val |= mask; + } + + regs->gpr[rd] = out_val; +} + static nokprobe_inline int trap_compare(long v1, long v2) { int ret = 0; @@ -1049,6 +1066,13 @@ int analyse_instr(struct instruction_op *op, struct pt_regs *regs, do_cmp_unsigned(regs, val, val2, rd >> 2); goto instr_done; + case 19173952: /* cmpb */ + val = regs->gpr[rd]; + val2 = regs->gpr[rb]; + + do_cmpb(regs, val, val2, ra); + goto instr_done; + /* * Arithmetic instructions */
This patch adds emulation of the cmpb instruction, enabling xmon to emulate this instruction. Signed-off-by: Matt Brown <matthew.brown.dev@gmail.com> --- arch/powerpc/lib/sstep.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)