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Using tools like systemtap on can consult DWARF information and put probes in the middle of the function and access local variables as well, that is not the real problem. The issue here is compiler doesn't seem to generate required DWARF information in some cases due to optimizations. The other related problem is when there exists debug information, the way to specify the breakpoint location is using line number which is not maintainable, having a marker solves this problem as well. Your proposal still doesn't solve the need for markers if i understood correctly.[...] Depends what we're trying to fix. I was trying to fix two things:
1. Flexibility - kprobes seem unable to access all local variables etc easily, and go anywhere inside the function. Plus keeping low overhead for doing things like keeping counters in a function (see previous example I mentioned for counting pages in shrink_list).
2. Overhead of the int3, which was allegedly 1000 cycles or so, though faster after Ingo had played with it, it's still significant.
ins1: 1st Instruction ins2: 2nd Instruction ins3: 3rd Instruction IA: Insertion Address JTPR: Jump Target Prohibition Region DCR: Detoured Code Region
M.
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