On 9/23/20 2:38 AM, Kele Huang wrote:
> Detect mips store instructions in cpu_signal_handler for all MIPS
> versions, and set is_write if encountering such store instructions.
>
> This fixed the error while dealing with self-modifed code for MIPS.
>
> Signed-off-by: Kele Huang <kele.hw...@gmail.com>
> Signed-off-by: Xu Zou <iwatchn...@gmail.com>
> ---
> accel/tcg/user-exec.c | 51 ++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 50 insertions(+), 1 deletion(-)
>
> diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
> index bb039eb32d..18784516e5 100644
> --- a/accel/tcg/user-exec.c
> +++ b/accel/tcg/user-exec.c
> @@ -710,11 +710,60 @@ int cpu_signal_handler(int host_signum, void *pinfo,
> greg_t pc = uc->uc_mcontext.pc;
> int is_write;
>
> - /* XXX: compute is_write */
> is_write = 0;
> +
> + /* Detect store by reading the instruction at the program counter. */
> + uint32_t insn = *(uint32_t *)pc;
> + switch(insn>>29) {
This would be easier if you simply looked at the entire major opcode field,
beginning at bit 26.
> + case 0x5:
> + switch((insn>>26) & 0x7) {
> + case 0x0: /* SB */
> + case 0x1: /* SH */
> + case 0x2: /* SWL */
> + case 0x3: /* SW */
> + case 0x4: /* SDL */
> + case 0x5: /* SDR */
> + case 0x6: /* SWR */
> + is_write = 1;
> + }
So this becomes
case 050: /* SB */
case 051: /* SH */
...
I know there are some who don't like octal, but IMO MIPS and its 6 bit fields
and 8x8 tables is a natural fit -- one can read the two octal digits right off
of the table.
Otherwise, perhaps you'd prefer binary constants like 0b101000. But with these
tables I find the mental bit-extract from hex to be tiresome.
> + break;
> + case 0x7:
> + switch((insn>>26) & 0x7) {
> + case 0x0: /* SC */
> + case 0x1: /* SWC1 */
> + case 0x4: /* SCD */
> + case 0x5: /* SDC1 */
> + case 0x7: /* SD */
> +#if !defined(__mips_isa_rev) || __mips_isa_rev < 6
> + case 0x2: /* SWC2 */
> + case 0x6: /* SDC2 */
> +#endif
> + is_write = 1;
Similarly.
> + }
> + break;
> + }
> +
> + /*
> + * Required in all versions of MIPS64 since MIPS64r1. Not available
> + * in MIPS32r1. Required by MIPS32r2 and subsequent versions of MIPS32.
> + */
> + switch ((insn >> 3) & 0x7) {
> + case 0x1:
> + switch (insn & 0x7) {
> + case 0x0: /* SWXC1 */
> + case 0x1: /* SDXC1 */
> + is_write = 1;
> + }
> + break;
> + }
This switch is incorrectly placed. It must be within the first switch, under
major opcode 023 (COP1X). And again, you should extract the entire 6-bit minor
opcode all at once, not one octal digit at a time.
> +#elif defined(__misp16) || defined(__mips_micromips)
> +
> +#error "Unsupported encoding"
This is incorrectly placed, because we've already successfully entered the
preceeding #elif defined(__mips__). This needs to be
#elif defined(__mips__)
# if defined(__mips16) || defined(__mips_micromips)
# error
# endif
int cpu_signal_handler(int host_signum, void *pinfo,
void *puc)
{
...
}
#elif defined(__riscv)
r~
