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//===- Unix/Memory.cpp - Generic UNIX System Configuration ------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines some functions for various memory management utilities.
//
//===----------------------------------------------------------------------===//
#include "Unix.h"
#include "llvm/Config/config.h"
#include "llvm/Support/Alignment.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Process.h"
#ifdef HAVE_SYS_MMAN_H
#include <sys/mman.h>
#endif
#ifdef __APPLE__
#include <mach/mach.h>
#endif
#ifdef __Fuchsia__
#include <zircon/syscalls.h>
#endif
#if defined(__APPLE__)
extern "C" void sys_icache_invalidate(const void *Addr, size_t len);
#else
extern "C" void __clear_cache(void *, void*);
#endif
static int getPosixProtectionFlags(unsigned Flags) {
switch (Flags & llvm::sys::Memory::MF_RWE_MASK) {
case llvm::sys::Memory::MF_READ:
return PROT_READ;
case llvm::sys::Memory::MF_WRITE:
return PROT_WRITE;
case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_WRITE:
return PROT_READ | PROT_WRITE;
case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_EXEC:
return PROT_READ | PROT_EXEC;
case llvm::sys::Memory::MF_READ | llvm::sys::Memory::MF_WRITE |
llvm::sys::Memory::MF_EXEC:
return PROT_READ | PROT_WRITE | PROT_EXEC;
case llvm::sys::Memory::MF_EXEC:
#if (defined(__FreeBSD__) || defined(__POWERPC__) || defined (__ppc__) || \
defined(_POWER) || defined(_ARCH_PPC))
// On PowerPC, having an executable page that has no read permission
// can have unintended consequences. The function InvalidateInstruction-
// Cache uses instructions dcbf and icbi, both of which are treated by
// the processor as loads. If the page has no read permissions,
// executing these instructions will result in a segmentation fault.
return PROT_READ | PROT_EXEC;
#else
return PROT_EXEC;
#endif
default:
llvm_unreachable("Illegal memory protection flag specified!");
}
// Provide a default return value as required by some compilers.
return PROT_NONE;
}
namespace llvm {
namespace sys {
MemoryBlock
Memory::allocateMappedMemory(size_t NumBytes,
const MemoryBlock *const NearBlock,
unsigned PFlags,
std::error_code &EC) {
EC = std::error_code();
if (NumBytes == 0)
return MemoryBlock();
// On platforms that have it, we can use MAP_ANON to get a memory-mapped
// page without file backing, but we need a fallback of opening /dev/zero
// for strictly POSIX platforms instead.
int fd;
#if defined(MAP_ANON)
fd = -1;
#else
fd = open("/dev/zero", O_RDWR);
if (fd == -1) {
EC = std::error_code(errno, std::generic_category());
return MemoryBlock();
}
#endif
int MMFlags = MAP_PRIVATE;
#if defined(MAP_ANON)
MMFlags |= MAP_ANON;
#endif
int Protect = getPosixProtectionFlags(PFlags);
#if defined(__NetBSD__) && defined(PROT_MPROTECT)
Protect |= PROT_MPROTECT(PROT_READ | PROT_WRITE | PROT_EXEC);
#endif
// Use any near hint and the page size to set a page-aligned starting address
uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
NearBlock->allocatedSize() : 0;
static const size_t PageSize = Process::getPageSizeEstimate();
const size_t NumPages = (NumBytes+PageSize-1)/PageSize;
if (Start && Start % PageSize)
Start += PageSize - Start % PageSize;
// FIXME: Handle huge page requests (MF_HUGE_HINT).
void *Addr = ::mmap(reinterpret_cast<void *>(Start), PageSize*NumPages, Protect,
MMFlags, fd, 0);
if (Addr == MAP_FAILED) {
if (NearBlock) { //Try again without a near hint
#if !defined(MAP_ANON)
close(fd);
#endif
return allocateMappedMemory(NumBytes, nullptr, PFlags, EC);
}
EC = std::error_code(errno, std::generic_category());
#if !defined(MAP_ANON)
close(fd);
#endif
return MemoryBlock();
}
#if !defined(MAP_ANON)
close(fd);
#endif
MemoryBlock Result;
Result.Address = Addr;
Result.AllocatedSize = PageSize*NumPages;
Result.Flags = PFlags;
// Rely on protectMappedMemory to invalidate instruction cache.
if (PFlags & MF_EXEC) {
EC = Memory::protectMappedMemory (Result, PFlags);
if (EC != std::error_code())
return MemoryBlock();
}
return Result;
}
std::error_code
Memory::releaseMappedMemory(MemoryBlock &M) {
if (M.Address == nullptr || M.AllocatedSize == 0)
return std::error_code();
if (0 != ::munmap(M.Address, M.AllocatedSize))
return std::error_code(errno, std::generic_category());
M.Address = nullptr;
M.AllocatedSize = 0;
return std::error_code();
}
std::error_code
Memory::protectMappedMemory(const MemoryBlock &M, unsigned Flags) {
static const Align PageSize = Align(Process::getPageSizeEstimate());
if (M.Address == nullptr || M.AllocatedSize == 0)
return std::error_code();
if (!Flags)
return std::error_code(EINVAL, std::generic_category());
int Protect = getPosixProtectionFlags(Flags);
uintptr_t Start = alignAddr((const uint8_t *)M.Address - PageSize.value() + 1, PageSize);
uintptr_t End = alignAddr((const uint8_t *)M.Address + M.AllocatedSize, PageSize);
bool InvalidateCache = (Flags & MF_EXEC);
#if defined(__arm__) || defined(__aarch64__)
// Certain ARM implementations treat icache clear instruction as a memory read,
// and CPU segfaults on trying to clear cache on !PROT_READ page. Therefore we need
// to temporarily add PROT_READ for the sake of flushing the instruction caches.
if (InvalidateCache && !(Protect & PROT_READ)) {
int Result = ::mprotect((void *)Start, End - Start, Protect | PROT_READ);
if (Result != 0)
return std::error_code(errno, std::generic_category());
Memory::InvalidateInstructionCache(M.Address, M.AllocatedSize);
InvalidateCache = false;
}
#endif
int Result = ::mprotect((void *)Start, End - Start, Protect);
if (Result != 0)
return std::error_code(errno, std::generic_category());
if (InvalidateCache)
Memory::InvalidateInstructionCache(M.Address, M.AllocatedSize);
return std::error_code();
}
/// InvalidateInstructionCache - Before the JIT can run a block of code
/// that has been emitted it must invalidate the instruction cache on some
/// platforms.
void Memory::InvalidateInstructionCache(const void *Addr,
size_t Len) {
// icache invalidation for PPC and ARM.
#if defined(__APPLE__)
# if (defined(__POWERPC__) || defined (__ppc__) || \
defined(_POWER) || defined(_ARCH_PPC) || defined(__arm__) || \
defined(__arm64__))
sys_icache_invalidate(const_cast<void *>(Addr), Len);
# endif
#elif defined(__Fuchsia__)
zx_status_t Status = zx_cache_flush(Addr, Len, ZX_CACHE_FLUSH_INSN);
assert(Status == ZX_OK && "cannot invalidate instruction cache");
#else
# if (defined(__POWERPC__) || defined (__ppc__) || \
defined(_POWER) || defined(_ARCH_PPC)) && defined(__GNUC__)
const size_t LineSize = 32;
const intptr_t Mask = ~(LineSize - 1);
const intptr_t StartLine = ((intptr_t) Addr) & Mask;
const intptr_t EndLine = ((intptr_t) Addr + Len + LineSize - 1) & Mask;
for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
asm volatile("dcbf 0, %0" : : "r"(Line));
asm volatile("sync");
for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
asm volatile("icbi 0, %0" : : "r"(Line));
asm volatile("isync");
# elif (defined(__arm__) || defined(__aarch64__) || defined(__mips__)) && \
defined(__GNUC__)
// FIXME: Can we safely always call this for __GNUC__ everywhere?
const char *Start = static_cast<const char *>(Addr);
const char *End = Start + Len;
__clear_cache(const_cast<char *>(Start), const_cast<char *>(End));
# endif
#endif // end apple
ValgrindDiscardTranslations(Addr, Len);
}
} // namespace sys
} // namespace llvm
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