gcc/libcilkrts/runtime/cilk_fiber-unix.cpp

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/* cilk_fiber-unix.cpp -*-C++-*-
*
*************************************************************************
*
* @copyright
* Copyright (C) 2012-2013, Intel Corporation
* All rights reserved.
*
* @copyright
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Intel Corporation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* @copyright
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
* WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
**************************************************************************/
#include "cilk_fiber-unix.h"
#include "cilk_malloc.h"
#include "bug.h"
#include "os.h"
#include <cstdio>
#include <cstdlib>
#include <errno.h>
#include <sys/mman.h>
#include <unistd.h>
// You'd think that getting a defintion for alloca would be easy. But you'd
// be wrong. Here's a variant on what's recommended in the autoconf doc. I've
// remove the Windows portion since this is Unix-specific code.
#if defined HAVE_ALLOCA_H
# include <alloca.h>
#elif defined __GNUC__
# define alloca __builtin_alloca
#elif defined _AIX
# define alloca __alloca
#else
# include <stddef.h>
# ifdef __cplusplus
extern "C"
# endif
void *alloca (size_t);
#endif
// MAP_ANON is deprecated on Linux, but seems to be required on Mac...
#ifndef MAP_ANONYMOUS
#define MAP_ANONYMOUS MAP_ANON
#endif
// Magic number for sanity checking fiber structure
const unsigned magic_number = 0x5afef00d;
int cilk_fiber_sysdep::s_page_size = getpagesize();
cilk_fiber_sysdep::cilk_fiber_sysdep(std::size_t stack_size)
: cilk_fiber(stack_size)
, m_magic(magic_number)
{
// Set m_stack and m_stack_base.
make_stack(stack_size);
// Get high-address of stack, with 32-bytes of spare space, and rounded
// down to the nearest 32-byte boundary.
const uintptr_t align_mask = 32 - 1;
m_stack_base -= ((std::size_t) m_stack_base) & align_mask;
}
cilk_fiber_sysdep::cilk_fiber_sysdep(from_thread_t)
: cilk_fiber()
, m_magic(magic_number)
{
this->set_allocated_from_thread(true);
// Dummy stack data for thread-main fiber
m_stack = NULL;
m_stack_base = NULL;
}
void cilk_fiber_sysdep::convert_fiber_back_to_thread()
{
// Does nothing on Linux.
}
cilk_fiber_sysdep::~cilk_fiber_sysdep()
{
CILK_ASSERT(magic_number == m_magic);
if (!this->is_allocated_from_thread())
free_stack();
}
#if SUPPORT_GET_CURRENT_FIBER
cilk_fiber_sysdep* cilk_fiber_sysdep::get_current_fiber_sysdep()
{
return cilkos_get_tls_cilk_fiber();
}
#endif
// Jump to resume other fiber. We may or may not come back.
inline void cilk_fiber_sysdep::resume_other_sysdep(cilk_fiber_sysdep* other)
{
if (other->is_resumable()) {
other->set_resumable(false);
// Resume by longjmp'ing to the place where we suspended.
CILK_LONGJMP(other->m_resume_jmpbuf);
}
else {
// Otherwise, we've never ran this fiber before. Start the
// proc method.
other->run();
}
}
void cilk_fiber_sysdep::suspend_self_and_resume_other_sysdep(cilk_fiber_sysdep* other)
{
#if SUPPORT_GET_CURRENT_FIBER
cilkos_set_tls_cilk_fiber(other);
#endif
CILK_ASSERT(this->is_resumable());
// Jump to the other fiber. We expect to come back.
if (! CILK_SETJMP(m_resume_jmpbuf)) {
resume_other_sysdep(other);
}
// Return here when another fiber resumes me.
// If the fiber that switched to me wants to be deallocated, do it now.
do_post_switch_actions();
}
NORETURN cilk_fiber_sysdep::jump_to_resume_other_sysdep(cilk_fiber_sysdep* other)
{
#if SUPPORT_GET_CURRENT_FIBER
cilkos_set_tls_cilk_fiber(other);
#endif
CILK_ASSERT(!this->is_resumable());
// Jump to the other fiber. But we are never coming back because
// this fiber is being reset.
resume_other_sysdep(other);
// We should never come back here...
__cilkrts_bug("Should not get here");
}
// GCC doesn't allow us to call __builtin_longjmp in the same function that
// calls __builtin_setjmp, so create a new function to house the call to
// __builtin_longjmp
static void __attribute__((noinline))
do_cilk_longjmp(__CILK_JUMP_BUFFER jmpbuf)
{
CILK_LONGJMP(jmpbuf);
}
NORETURN cilk_fiber_sysdep::run()
{
// Only fibers created from a pool have a proc method to run and execute.
CILK_ASSERT(m_start_proc);
CILK_ASSERT(!this->is_allocated_from_thread());
CILK_ASSERT(!this->is_resumable());
// TBD: This setjmp/longjmp pair simply changes the stack pointer.
// We could probably replace this code with some assembly.
if (! CILK_SETJMP(m_resume_jmpbuf))
{
// Calculate the size of the current stack frame (i.e., this
// run() function.
size_t frame_size = (size_t)JMPBUF_FP(m_resume_jmpbuf) - (size_t)JMPBUF_SP(m_resume_jmpbuf);
// Macs require 16-byte alignment. Do it always because it just
// doesn't matter
if (frame_size & (16-1))
frame_size += 16 - (frame_size & (16-1));
// Assert that we are getting a reasonable frame size out of
// it. If this run() function is using more than 4096 bytes
// of space for its local variables / any state that spills to
// registers, something is probably *very* wrong here...
//
// 4096 bytes just happens to be a number that seems "large
// enough" --- for an example GCC 32-bit compilation, the
// frame size was 48 bytes.
CILK_ASSERT(frame_size < 4096);
// Change stack pointer to fiber stack. Offset the
// calculation by the frame size, so that we've allocated
// enough extra space from the top of the stack we are
// switching to for any temporaries required for this run()
// function.
JMPBUF_SP(m_resume_jmpbuf) = m_stack_base - frame_size;
// GCC doesn't allow us to call __builtin_longjmp in the same function
// that calls __builtin_setjmp, so it's been moved into it's own
// function that cannot be inlined.
do_cilk_longjmp(m_resume_jmpbuf);
}
// Note: our resetting of the stack pointer is valid only if the
// compiler has not saved any temporaries onto the stack for this
// function before the longjmp that we still care about at this
// point.
// Verify that 1) 'this' is still valid and 2) '*this' has not been
// corrupted.
CILK_ASSERT(magic_number == m_magic);
// If the fiber that switched to me wants to be deallocated, do it now.
do_post_switch_actions();
// Now call the user proc on the new stack
m_start_proc(this);
// alloca() to force generation of frame pointer. The argument to alloca
// is contrived to prevent the compiler from optimizing it away. This
// code should never actually be executed.
int* dummy = (int*) alloca((sizeof(int) + (std::size_t) m_start_proc) & 0x1);
*dummy = 0xface;
// User proc should never return.
__cilkrts_bug("Should not get here");
}
void cilk_fiber_sysdep::make_stack(size_t stack_size)
{
char* p;
// We've already validated that the stack size is page-aligned and
// is a reasonable value. No need to do any extra rounding here.
size_t rounded_stack_size = stack_size;
// Normally, we have already validated that the stack size is
// aligned to 4K. In the rare case that pages are huge though, we
// need to do some extra checks.
if (rounded_stack_size < 3 * (size_t)s_page_size) {
// If the specified stack size is too small, round up to 3
// pages. We need at least 2 extra for the guard pages.
rounded_stack_size = 3 * (size_t)s_page_size;
}
else {
// Otherwise, the stack size is large enough, but might not be
// a multiple of page size. Round up to nearest multiple of
// s_page_size, just to be safe.
size_t remainder = rounded_stack_size % s_page_size;
if (remainder) {
rounded_stack_size += s_page_size - remainder;
}
}
p = (char*)mmap(0, rounded_stack_size,
PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS,
-1, 0);
if (MAP_FAILED == p) {
// For whatever reason (probably ran out of memory), mmap() failed.
// There is no stack to return, so the program loses parallelism.
m_stack = NULL;
m_stack_base = NULL;
return;
}
// mprotect guard pages.
mprotect(p + rounded_stack_size - s_page_size, s_page_size, PROT_NONE);
mprotect(p, s_page_size, PROT_NONE);
m_stack = p;
m_stack_base = p + rounded_stack_size - s_page_size;
}
void cilk_fiber_sysdep::free_stack()
{
if (m_stack) {
size_t rounded_stack_size = m_stack_base - m_stack + s_page_size;
if (munmap(m_stack, rounded_stack_size) < 0)
__cilkrts_bug("Cilk: stack munmap failed error %d\n", errno);
}
}
/* End cilk_fiber-unix.cpp */