Messages in this thread | | | Date | Thu, 19 Mar 2009 23:40:17 -0400 | From | Masami Hiramatsu <> | Subject | Re: [RFC][PATCH -tip 7/9] tracing: kprobe-tracer plugin supports arguments |
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Frederic Weisbecker wrote: >> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c >> index 33bb355..e801e8c 100644 >> --- a/kernel/trace/trace_kprobe.c >> +++ b/kernel/trace/trace_kprobe.c >> @@ -27,15 +27,124 @@ >> #include <linux/types.h> >> #include <linux/string.h> >> #include <linux/ctype.h> >> +#include <linux/ptrace.h> >> >> #include <linux/ftrace.h> >> #include "trace.h" >> >> +/* TODO: Move these functions to arch/XXX/include/asm/ptrace.h */ >> +#define STACK_MASK (THREAD_SIZE - 1) >> +#define valid_stack_addr(regs, addr) \ >> + (((addr) & ~STACK_MASK) == (kernel_trap_sp(regs) & ~STACK_MASK)) >> + >> +#if defined(__i386__) >> +#define MAX_REG_NUM 15 >> +#elif defined(__x86_64__) >> +#define MAX_REG_NUM 21 >> +#else >> +#define MAX_REG_NUM (sizeof(struct pt_regs)/sizeof(unsigned long)) >> +#endif >> + >> +static unsigned long fetch_register(struct pt_regs *regs, void *num) >> +{ >> + if (unlikely((unsigned)num > MAX_REG_NUM)) >> + return 0; >> + return *((unsigned long *)regs + (unsigned)num); >> +} >> + >> +static unsigned long fetch_stack(struct pt_regs *regs, void *num) >> +{ >> + unsigned long *addr = (unsigned long *)kernel_trap_sp(regs); >> + addr += (unsigned)num; >> + if (valid_stack_addr(regs, (unsigned long)addr)) >> + return *addr; >> + else >> + return 0; >> +} >> + >> +static unsigned long fetch_memory(struct pt_regs *regs, void *addr) >> +{ >> + unsigned long retval; >> + probe_kernel_address(addr, retval); >> + return retval; >> +} > > > It will return a random value.
ah, thanks. I'll check the retval of probe_kernel_address().
>> + >> +#if defined(__i386__) >> +#define REGPARMS 3 >> +static unsigned long fetch_argument(struct pt_regs *regs, void *data) >> +{ >> + unsigned long n = (unsigned long)data; >> + if (n > REGPARMS) { >> + /* >> + * The typical case: arg n is on the stack. >> + * stack[0] = return address >> + */ >> + return fetch_stack(regs, (void *)(n - REGPARMS)); >> + } else { >> + switch (n) { >> + case 1: return regs->ax; >> + case 2: return regs->dx; >> + case 3: return regs->cx; >> + } >> + return 0; >> + } >> +} >> +#elif define(__x86_64__) >> +#define REGPARMS 6 > > > These helpers could be defined in the appropriate arch directory. > They may even be reused by further debugging engines.
Agreed. Since we don't have any those infrastructure (arch/*/lib/debug.c ?) yet, I just put it in trace_kprobe.c.
Thank you,
-- Masami Hiramatsu
Software Engineer Hitachi Computer Products (America) Inc. Software Solutions Division
e-mail: mhiramat@redhat.com
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