Messages in this thread | | | Date | Mon, 06 Jul 2009 15:28:02 -0400 | From | Masami Hiramatsu <> | Subject | Re: [PATCH -tip -v10 5/7] x86: add pt_regs register and stack access APIs |
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Andi Kleen wrote: > Masami Hiramatsu <mhiramat@redhat.com> writes: > >> Add following APIs for accessing registers and stack entries from pt_regs. > > You forgot to state who calls these functions/why are they added? > Who only has strings for registers?
Oh, yes. This patch is needed for kprobes based event tracer on ftrace. Some other debugging tools might be able to use it.
> I can see the point of having a function for nth argument though, > that's useful. > >> +static inline unsigned long regs_get_argument_nth(struct pt_regs *regs, >> + unsigned n) >> +{ >> + if (n < NR_REGPARMS) { >> + switch (n) { >> + case 0: >> + return regs->ax; >> + case 1: >> + return regs->dx; >> + case 2: >> + return regs->cx; > > > [....] > > That could be done shorter with a offsetof table. > >> + if (n < NR_REGPARMS) { >> + switch (n) { >> + case 0: >> + return regs->di; >> + case 1: >> + return regs->si; >> + case 2: >> + return regs->dx; >> + case 3: >> + return regs->cx; >> + case 4: >> + return regs->r8; >> + case 5: >> + return regs->r9; > > and that too.
I'm not so sure about your idea. Would you mean below code?
int offs_table[NR_REGPARMS] = { [0] = offsetof(struct pt_regs, di), ... }; if (n < NR_REGPARMS) return *((unsigned long *)regs + offs_table[n]);
Thank you,
-- Masami Hiramatsu
Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division
e-mail: mhiramat@redhat.com
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