Libc-498.tar.gz

[apple/libc.git] / gen / thread_stack_pcs.c

diff --git a/gen/thread_stack_pcs.c b/gen/thread_stack_pcs.c
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+/*
+ * Copyright (c) 1999, 2007 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+/*     Bertrand from vmutils -> CF -> System */
+
+#include <pthread.h>
+#include <mach/mach.h>
+#include <mach/vm_statistics.h>
+#include <stdlib.h>
+
+#if defined(__i386__) || defined(__x86_64__)
+#define FP_LINK_OFFSET 1
+#elif defined(__ppc__) || defined(__ppc64__)
+#define FP_LINK_OFFSET 2
+#else
+#error  ********** Unimplemented architecture
+#endif
+
+#define        INSTACK(a)      ((a) >= stackbot && (a) <= stacktop)
+#if defined(__ppc__) || defined(__ppc64__) || defined(__x86_64__)
+#define        ISALIGNED(a)    ((((uintptr_t)(a)) & 0xf) == 0)
+#elif defined(__i386__)
+#define        ISALIGNED(a)    ((((uintptr_t)(a)) & 0xf) == 8)
+#endif
+
+__private_extern__  __attribute__((noinline))
+void
+_thread_stack_pcs(vm_address_t *buffer, unsigned max, unsigned *nb, unsigned skip)
+{
+    void *frame, *next;
+    pthread_t self = pthread_self();
+    void *stacktop = pthread_get_stackaddr_np(self);
+    void *stackbot = stacktop - pthread_get_stacksize_np(self);
+
+    *nb = 0;
+
+    /* make sure return address is never out of bounds */
+    stacktop -= (FP_LINK_OFFSET + 1) * sizeof(void *);
+
+    /*
+     * The original implementation called the first_frame_address() function,
+     * which returned the stack frame pointer.  The problem was that in ppc,
+     * it was a leaf function, so no new stack frame was set up with
+     * optimization turned on (while a new stack frame was set up without
+     * optimization).  We now inline the code to get the stack frame pointer,
+     * so we are consistent about the stack frame.
+     */
+#if defined(__i386__) || defined(__x86_64__)
+    frame = __builtin_frame_address(0);
+#elif defined(__ppc__) || defined(__ppc64__)
+    /* __builtin_frame_address IS BROKEN IN BEAKER: RADAR #2340421 */
+    __asm__ volatile("mr %0, r1" : "=r" (frame));
+#endif
+    if(!INSTACK(frame) || !ISALIGNED(frame))
+       return;
+#if defined(__ppc__) || defined(__ppc64__)
+    /* back up the stack pointer up over the current stack frame */
+    next = *(void **)frame;
+    if(!INSTACK(next) || !ISALIGNED(next) || next <= frame)
+       return;
+    frame = next;
+#endif
+    while (skip--) {
+       next = *(void **)frame;
+       if(!INSTACK(next) || !ISALIGNED(next) || next <= frame)
+           return;
+       frame = next;
+    }
+    while (max--) {
+        buffer[*nb] = *(vm_address_t *)(((void **)frame) + FP_LINK_OFFSET);
+        (*nb)++;
+       next = *(void **)frame;
+       if(!INSTACK(next) || !ISALIGNED(next) || next <= frame)
+           return;
+       frame = next;
+    }
+}
+
+void
+thread_stack_pcs(vm_address_t *buffer, unsigned max, unsigned *nb)
+{
+    _thread_stack_pcs(buffer, max, nb, 0);
+
+    // The following prevents thread_stack_pcs() from getting tail-call-optimized into _thread_stack_pcs() on 64-bit environments,
+    // thus making the "number of hot frames to skip" be more predictable, giving more consistent backtraces.
+    // See <rdar://problem/5364825> "stack logging: frames keep getting truncated" for why this is necessary.
+    __asm__ volatile("");
+}