Richard Henderson <richard.hender...@linaro.org> writes:
> Trigger breakpoints before beginning translation of a TB > that would begin with a BP. Thus we never generate code > for the BP at all. > > Single-step instructions within a page containing a BP so > that we are sure to check each insn for the BP as above. > > We no longer need to flush any TBs when changing BPs. > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/286 > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/404 > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/489 > Signed-off-by: Richard Henderson <richard.hender...@linaro.org> However... > > +static bool check_for_breakpoints(CPUState *cpu, target_ulong pc, > + uint32_t *cflags) > +{ > + CPUBreakpoint *bp; > + bool match_page = false; > + > + if (likely(QTAILQ_EMPTY(&cpu->breakpoints))) { > + return false; > + } > + > + QTAILQ_FOREACH(bp, &cpu->breakpoints, entry) { > + /* > + * If we have an exact pc match, trigger the breakpoint. > + * Otherwise, note matches within the page. > + */ > + if (pc == bp->pc) { > + bool match_bp = false; > + > + if (bp->flags & BP_GDB) { > + match_bp = true; > + } else if (bp->flags & BP_CPU) { > +#ifdef CONFIG_USER_ONLY > + g_assert_not_reached(); > +#else > + CPUClass *cc = CPU_GET_CLASS(cpu); > + assert(cc->tcg_ops->debug_check_breakpoint); > + match_bp = cc->tcg_ops->debug_check_breakpoint(cpu); > +#endif > + } > + > + if (match_bp) { > + cpu->exception_index = EXCP_DEBUG; > + return true; > + } > + } else if (((pc ^ bp->pc) & TARGET_PAGE_MASK) == 0) { > + match_page = true; > + } > + } > + > + /* > + * Within the same page as a breakpoint, single-step, > + * returning to helper_lookup_tb_ptr after each looking > + * for the actual breakpoint. > + * > + * TODO: Perhaps better to record all of the TBs associated > + * with a given virtual page that contains a breakpoint, and > + * then invalidate them when a new overlapping breakpoint is > + * set on the page. Non-overlapping TBs would not be > + * invalidated, nor would any TB need to be invalidated as > + * breakpoints are removed. > + */ > + if (match_page) { > + *cflags = (*cflags & ~CF_COUNT_MASK) | CF_NO_GOTO_TB | 1; > + } > + return false; > +} > + This seems to have a really negative effect on: ./tests/venv/bin/avocado run tests/acceptance/reverse_debugging.py:ReverseDebugging_AArch64.test_aarch64_virt Even bumping the timeout up from 10 to 300 isn't enough to get it working. I'm not sure if this is a time or a hang. -- Alex Bennée
