Messages in this thread | | | Date | Tue, 24 Nov 2009 21:19:22 +0100 | From | Frederic Weisbecker <> | Subject | Re: [PATCH -tip v5 06/10] kprobes/x86: Cleanup save/restore registers |
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On Tue, Nov 24, 2009 at 10:39:13AM -0500, Masami Hiramatsu wrote: > Frederic Weisbecker wrote: > > On Mon, Nov 23, 2009 at 06:22:04PM -0500, Masami Hiramatsu wrote: > >> +#ifdef CONFIG_X86_64 > >> +#define SAVE_REGS_STRING \ > >> + /* Skip cs, ip, orig_ax. */ \ > >> + " subq $24, %rsp\n" \ > >> + " pushq %rdi\n" \ > >> + " pushq %rsi\n" \ > >> + " pushq %rdx\n" \ > >> + " pushq %rcx\n" \ > >> + " pushq %rax\n" \ > >> + " pushq %r8\n" \ > >> + " pushq %r9\n" \ > >> + " pushq %r10\n" \ > >> + " pushq %r11\n" \ > >> + " pushq %rbx\n" \ > >> + " pushq %rbp\n" \ > >> + " pushq %r12\n" \ > >> + " pushq %r13\n" \ > >> + " pushq %r14\n" \ > >> + " pushq %r15\n" > >> +#define RESTORE_REGS_STRING \ > >> + " popq %r15\n" \ > >> + " popq %r14\n" \ > >> + " popq %r13\n" \ > >> + " popq %r12\n" \ > >> + " popq %rbp\n" \ > >> + " popq %rbx\n" \ > >> + " popq %r11\n" \ > >> + " popq %r10\n" \ > >> + " popq %r9\n" \ > >> + " popq %r8\n" \ > >> + " popq %rax\n" \ > >> + " popq %rcx\n" \ > >> + " popq %rdx\n" \ > >> + " popq %rsi\n" \ > >> + " popq %rdi\n" \ > > > > > > BTW, do you really need to push/pop every registers > > before/after calling a probe handler? > > Yes, in both cases (kretprobe/optprpbe) it needs to > emulate kprobes behavior. kprobes can be used as > fault injection, it should pop pt_regs. > > > Is it possible to only save/restore the scratch ones? > > Hmm, what code did you mean?
Ah this chain of push/pop is there to dump a struct pt_regs for the handler? Sorry, I just thought it was to save the registers from the probed function.
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