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sim-se: add a faux-filesystem

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This change introduces the concept of a faux-filesystem.
The faux-filesystem creates a directory structure in m5out
(or whatever output dir the user specifies) where system calls
may be redirected.

This is useful to avoid non-determinism when reading files
with varying path names (e.g., variations from run-to-run if
the simulation is scheduled on a cluster where paths may change).

Also, this changeset allows circumventing host pseudofiles which
have information specific to the host processor (such as cache
hierarchy or processor information). Bypassing host pseudofiles
can be useful when executing runtimes in the absence of an
operating system kernel since runtimes may try to query standard
files (i.e. /proc or /sys) which are not relevant to an
application executing in syscall emulation mode.

Change-Id: I90821b3b403168b904a662fa98b85def1628621c
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/12119
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This commit is contained in:
David Hashe
2018-04-18 16:36:55 -04:00
committed by Brandon Potter
parent e8d0b755ea
commit 54c77aa055
17 changed files with 755 additions and 94 deletions
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70
src/sim/syscall_emul.cc
View File

@@ -388,7 +388,7 @@ getcwdFunc(SyscallDesc *desc, int num, Process *p, ThreadContext *tc)
BufferArg buf(buf_ptr, size);
// Is current working directory defined?
string cwd = p->getcwd();
string cwd = p->tgtCwd;
if (!cwd.empty()) {
if (cwd.length() >= size) {
// Buffer too small
@@ -425,8 +425,8 @@ readlinkFunc(SyscallDesc *desc, int num, Process *p, ThreadContext *tc,
if (!tc->getMemProxy().tryReadString(path, p->getSyscallArg(tc, index)))
return -EFAULT;
// Adjust path for current working directory
path = p->fullPath(path);
// Adjust path for cwd and redirection
path = p->checkPathRedirect(path);
Addr buf_ptr = p->getSyscallArg(tc, index);
size_t bufsiz = p->getSyscallArg(tc, index);
@@ -491,7 +491,7 @@ unlinkHelper(SyscallDesc *desc, int num, Process *p, ThreadContext *tc,
if (!tc->getMemProxy().tryReadString(path, p->getSyscallArg(tc, index)))
return -EFAULT;
path = p->fullPath(path);
path = p->checkPathRedirect(path);
int result = unlink(path.c_str());
return (result == -1) ? -errno : result;
@@ -510,8 +510,8 @@ linkFunc(SyscallDesc *desc, int num, Process *p, ThreadContext *tc)
if (!virt_mem.tryReadString(new_path, p->getSyscallArg(tc, index)))
return -EFAULT;
path = p->fullPath(path);
new_path = p->fullPath(new_path);
path = p->absolutePath(path, true);
new_path = p->absolutePath(new_path, true);
int result = link(path.c_str(), new_path.c_str());
return (result == -1) ? -errno : result;
@@ -530,8 +530,8 @@ symlinkFunc(SyscallDesc *desc, int num, Process *p, ThreadContext *tc)
if (!virt_mem.tryReadString(new_path, p->getSyscallArg(tc, index)))
return -EFAULT;
path = p->fullPath(path);
new_path = p->fullPath(new_path);
path = p->absolutePath(path, true);
new_path = p->absolutePath(new_path, true);
int result = symlink(path.c_str(), new_path.c_str());
return (result == -1) ? -errno : result;
@@ -540,18 +540,15 @@ symlinkFunc(SyscallDesc *desc, int num, Process *p, ThreadContext *tc)
SyscallReturn
mkdirFunc(SyscallDesc *desc, int num, Process *p, ThreadContext *tc)
{
string path;
int index = 0;
std::string path;
if (!tc->getMemProxy().tryReadString(path, p->getSyscallArg(tc, index)))
return -EFAULT;
// Adjust path for current working directory
path = p->fullPath(path);
path = p->checkPathRedirect(path);
mode_t mode = p->getSyscallArg(tc, index);
int result = mkdir(path.c_str(), mode);
auto result = mkdir(path.c_str(), mode);
return (result == -1) ? -errno : result;
}
@@ -569,9 +566,9 @@ renameFunc(SyscallDesc *desc, int num, Process *p, ThreadContext *tc)
if (!tc->getMemProxy().tryReadString(new_name, p->getSyscallArg(tc, index)))
return -EFAULT;
// Adjust path for current working directory
old_name = p->fullPath(old_name);
new_name = p->fullPath(new_name);
// Adjust path for cwd and redirection
old_name = p->checkPathRedirect(old_name);
new_name = p->checkPathRedirect(new_name);
int64_t result = rename(old_name.c_str(), new_name.c_str());
return (result == -1) ? -errno : result;
@@ -588,8 +585,8 @@ truncateFunc(SyscallDesc *desc, int num, Process *p, ThreadContext *tc)
off_t length = p->getSyscallArg(tc, index);
// Adjust path for current working directory
path = p->fullPath(path);
// Adjust path for cwd and redirection
path = p->checkPathRedirect(path);
int result = truncate(path.c_str(), length);
return (result == -1) ? -errno : result;
@@ -623,8 +620,8 @@ truncate64Func(SyscallDesc *desc, int num,
int64_t length = process->getSyscallArg(tc, index, 64);
// Adjust path for current working directory
path = process->fullPath(path);
// Adjust path for cwd and redirection
path = process->checkPathRedirect(path);
#if NO_STAT64
int result = truncate(path.c_str(), length);
@@ -680,8 +677,8 @@ chownFunc(SyscallDesc *desc, int num, Process *p, ThreadContext *tc)
uint32_t group = p->getSyscallArg(tc, index);
gid_t hostGroup = group;
// Adjust path for current working directory
path = p->fullPath(path);
// Adjust path for cwd and redirection
path = p->checkPathRedirect(path);
int result = chown(path.c_str(), hostOwner, hostGroup);
return (result == -1) ? -errno : result;
@@ -1068,8 +1065,8 @@ accessFunc(SyscallDesc *desc, int callnum, Process *p, ThreadContext *tc,
if (!tc->getMemProxy().tryReadString(path, p->getSyscallArg(tc, index)))
return -EFAULT;
// Adjust path for current working directory
path = p->fullPath(path);
// Adjust path for cwd and redirection
path = p->checkPathRedirect(path);
mode_t mode = p->getSyscallArg(tc, index);
@@ -1091,7 +1088,7 @@ mknodFunc(SyscallDesc *desc, int num, Process *p, ThreadContext *tc)
if (!tc->getMemProxy().tryReadString(path, p->getSyscallArg(tc, index)))
return -EFAULT;
path = p->fullPath(path);
path = p->checkPathRedirect(path);
mode_t mode = p->getSyscallArg(tc, index);
dev_t dev = p->getSyscallArg(tc, index);
@@ -1107,10 +1104,23 @@ chdirFunc(SyscallDesc *desc, int num, Process *p, ThreadContext *tc)
if (!tc->getMemProxy().tryReadString(path, p->getSyscallArg(tc, index)))
return -EFAULT;
path = p->fullPath(path);
std::string tgt_cwd;
if (startswith(path, "/")) {
tgt_cwd = path;
} else {
char buf[PATH_MAX];
tgt_cwd = realpath((p->tgtCwd + "/" + path).c_str(), buf);
}
std::string host_cwd = p->checkPathRedirect(tgt_cwd);
auto result = chdir(path.c_str());
return (result == -1) ? -errno : result;
int result = chdir(host_cwd.c_str());
if (result == -1)
return -errno;
p->hostCwd = host_cwd;
p->tgtCwd = tgt_cwd;
return result;
}
SyscallReturn
@@ -1121,7 +1131,7 @@ rmdirFunc(SyscallDesc *desc, int num, Process *p, ThreadContext *tc)
if (!tc->getMemProxy().tryReadString(path, p->getSyscallArg(tc, index)))
return -EFAULT;
path = p->fullPath(path);
path = p->checkPathRedirect(path);
auto result = rmdir(path.c_str());
return (result == -1) ? -errno : result;