[linuxsh-dev] kernel debugging

[NIIBE Y. <gn...@m1...>]

Jeremy Siegel wrote:
 > Is there a reason not to apply the following patches for these?

Not at all.  Please do commit.

 >  /*
 >   * handle an instruction that does an unaligned memory access
 >   * - have to be careful of branch delay-slot instructions that fault
 > + *  SH3:
 >   *   - if the branch would be taken PC points to the branch
 >   *   - if the branch would not be taken, PC points to delay-slot
 > + *  SH4:
 > + *   - PC always points to delayed branch
 >   * - return 0 if handled, -EFAULT if failed (may not return if in kernel)
 >   */

I think that SH-4 was not on the focus at that time.

I have a comment on the expressions calculating PC.  It's OK, but
it would be good if we can improve the implementation.

 > +					regs->pc += ((signed char)(instruction&0x00FF))*2 + 4;
[...]
 > +					regs->pc += ((signed char)(instruction&0x00FF))*2 + 4;
[...]
 > +			regs->pc += (((signed short)(instruction<<4))>>3) + 4;
[...]
 > +			regs->pc += (((signed short)(instruction<<4))>>3) + 4;

We want something like "ext.b" or "ext.w" (of SuperH assembler) here.
In general, it's not good practice using type coercion to do the
calculation.
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