xnu-2050.7.9.tar.gz

[apple/xnu.git] / bsd / dev / i386 / sdt_x86.c

diff --git a/bsd/dev/i386/sdt_x86.c b/bsd/dev/i386/sdt_x86.c
index c354b303e19453171dd1b8ece9437882cec0aff4..680ed779b954ed5afc958538d489855833cd1b52 100644 (file)
--- a/bsd/dev/i386/sdt_x86.c
+++ b/bsd/dev/i386/sdt_x86.c
@@ -107,3 +107,115 @@ sdt_invop(uintptr_t addr, uintptr_t *stack, uintptr_t eax)
 #endif
 
 
+struct frame {
+    struct frame *backchain;
+    uintptr_t retaddr;
+};
+
+/*ARGSUSED*/
+uint64_t
+sdt_getarg(void *arg, dtrace_id_t id, void *parg, int argno, int aframes)
+{
+#pragma unused(arg, id, parg)    
+       uint64_t val;
+       struct frame *fp = (struct frame *)__builtin_frame_address(0);
+       uintptr_t *stack;
+       uintptr_t pc;
+       int i;
+
+#if defined(__x86_64__)
+    /*
+     * A total of 6 arguments are passed via registers; any argument with
+     * index of 5 or lower is therefore in a register.
+     */
+    int inreg = 5;
+#endif
+
+       for (i = 1; i <= aframes; i++) {
+               fp = fp->backchain;
+               pc = fp->retaddr;
+
+               if (dtrace_invop_callsite_pre != NULL
+                       && pc  >  (uintptr_t)dtrace_invop_callsite_pre
+                       && pc  <= (uintptr_t)dtrace_invop_callsite_post) {
+#if defined(__i386__)
+                       /*
+                        * If we pass through the invalid op handler, we will
+                        * use the pointer that it passed to the stack as the
+                        * second argument to dtrace_invop() as the pointer to
+                        * the frame we're hunting for.
+                        */
+
+                       stack = (uintptr_t *)&fp[1]; /* Find marshalled arguments */
+                       fp = (struct frame *)stack[1]; /* Grab *second* argument */
+                       stack = (uintptr_t *)&fp[0]; /* Find marshalled arguments */
+#elif defined(__x86_64__)
+                       /*
+                        * In the case of x86_64, we will use the pointer to the
+                        * save area structure that was pushed when we took the
+                        * trap.  To get this structure, we must increment
+                        * beyond the frame structure. If the
+                        * argument that we're seeking is passed on the stack,
+                        * we'll pull the true stack pointer out of the saved
+                        * registers and decrement our argument by the number
+                        * of arguments passed in registers; if the argument
+                        * we're seeking is passed in regsiters, we can just
+                        * load it directly.
+                        */
+
+                       /* fp points to frame of dtrace_invop() activation. */
+                       fp = fp->backchain; /* to fbt_perfcallback() activation. */
+                       fp = fp->backchain; /* to kernel_trap() activation. */
+                       fp = fp->backchain; /* to trap_from_kernel() activation. */
+                       
+                       x86_saved_state_t   *tagged_regs = (x86_saved_state_t *)&fp[1];
+                       x86_saved_state64_t *saved_state = saved_state64(tagged_regs);
+
+                       if (argno <= inreg) {
+                               stack = (uintptr_t *)&saved_state->rdi;
+                       } else {
+                               fp = (struct frame *)(saved_state->isf.rsp);
+                               stack = (uintptr_t *)&fp[0]; /* Find marshalled
+                                                               arguments */
+                               argno -= (inreg +1);
+                       }
+#else
+#error Unknown arch
+#endif
+                       goto load;
+               }
+       }
+
+       /*
+        * We know that we did not come through a trap to get into
+        * dtrace_probe() --  We arrive here when the provider has
+        * called dtrace_probe() directly.
+        * The probe ID is the first argument to dtrace_probe().
+        * We must advance beyond that to get the argX.
+        */
+       argno++; /* Advance past probeID */
+
+#if defined(__x86_64__)
+       if (argno <= inreg) {
+               /*
+                * This shouldn't happen.  If the argument is passed in a
+                * register then it should have been, well, passed in a
+                * register...
+                */
+               DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
+               return (0);
+       }
+
+       argno -= (inreg + 1);
+#endif
+       stack = (uintptr_t *)&fp[1]; /* Find marshalled arguments */
+
+load:
+       DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
+       /* dtrace_probe arguments arg0 ... arg4 are 64bits wide */
+       val = (uint64_t)(*(((uintptr_t *)stack) + argno));
+       DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
+
+       return (val);
+}
+