[sanitizer] [SystemZ] Implement internal_clone.

[kcc]

General question: is SystemZ a variant of Linux?
If not, such changes should not go to files named *_linux*.cc, instead they should go into separate files names *_systemz.cc
Same is true even if SystemZ *is* a Linux variant, but a significantly different from the regular one.

More generally, please prefer a separate file to multiple #ifdefs.

[• koriakin]

In D19159#402595, @kcc wrote:

General question: is SystemZ a variant of Linux?
If not, such changes should not go to files named *_linux*.cc, instead they should go into separate files names *_systemz.cc
Same is true even if SystemZ *is* a Linux variant, but a significantly different from the regular one.

More generally, please prefer a separate file to multiple #ifdefs.

SystemZ is a CPU (also known as z/Series, or s390x), not an OS.

[kcc]

Ok. We already have files with suffix aarch64 or aarch64.
Please try to follow this rule: do not add any new #ifdef unless

1. the ifdef is a single top-level ifdef in a separate file
2. you are adding an #elif to an already existing #ifdef/#elif sequence.

[• koriakin]

In D19159#402783, @kcc wrote:

Ok. We already have files with suffix aarch64 or aarch64.
Please try to follow this rule: do not add any new #ifdef unless

1. the ifdef is a single top-level ifdef in a separate file
2. you are adding an #elif to an already existing #ifdef/#elif sequence.

Well, technically the outer #elif in this patch does follow the rule (the inner ones don't, but they're much better justified).

Anyhow, here's the plan:

1. Revert the AvoidCVE... patch (it's not doing much good without ASan/MSan/TSan support anyhow).
2. Submit a patch creating sanitizer_linux_s390.cc and moving internal_mmap there.
3. Resubmit this patch with a dep on #2.
4. Resubmit AvoidCVE... patch with empty AvoidCVE...() in common code and with a dep on #2.

I have one more patch in queue that adds s390-specific code which will end up in sanitizer_linux_s390.cc, but it's going to be a while before I get all dependencies merged.

[• koriakin]

Depends on D19174.

[• koriakin]

Ping?

[kcc]

Wasn't this commited already?

[• koriakin]

In D19159#411114, @kcc wrote:

Wasn't this commited already?

Nope, you may be thinking of internal_mmap, not internal_clone.

[kcc]

LGTM.

Note that I did not try hard to review the s390 code as I don't know (nor care) about it enough.
Feel free to submit patches to files fully covered under ifdef SANITIZER_S390 w/o my review,
although I would recommend to find a reviewer who knows the s390 stuff.

compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.h

 #if SANITIZER_LINUX
 uptr internal_prctl(int option, uptr arg2, uptr arg3, uptr arg4, uptr arg5);
 // Used only by sanitizer_stoptheworld. Signal handlers that are actually used
 // (like the process-wide error reporting SEGV handler) must use
 // internal_sigaction instead.
 int internal_sigaction_norestorer(int signum, const void *act, void *oldact);
 void internal_sigdelset(__sanitizer_sigset_t *set, int signum);
 #if defined(__x86_64__) || defined(__mips__) || defined(__aarch64__) \
-  || defined(__powerpc64__)
+  || defined(__powerpc64__) || defined(__s390__)
 uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
                     int *parent_tidptr, void *newtls, int *child_tidptr);
 #endif
 #endif  // SANITIZER_LINUX
 
 // This class reads thread IDs from /proc/<pid>/task using only syscalls.
 class ThreadLister {
  public:

compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux_s390.cc

 //===----------------------------------------------------------------------===//
 
 #include "sanitizer_platform.h"
 
 #if SANITIZER_LINUX && SANITIZER_S390
 
 #include "sanitizer_linux.h"
 
+#include <errno.h>
 #include <sys/syscall.h>
 #include <unistd.h>
 
 namespace __sanitizer {
 
 // --------------- sanitizer_libc.h
 uptr internal_mmap(void *addr, uptr length, int prot, int flags, int fd,
                    OFF_T offset) {
# endif
   };
 # ifdef __s390x__
   return syscall(__NR_mmap, &params);
 # else
   return syscall(__NR_mmap2, &params);
 # endif
 }
 
+uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
+                    int *parent_tidptr, void *newtls, int *child_tidptr) {
+  if (!fn || !child_stack)
+    return -EINVAL;
+  CHECK_EQ(0, (uptr)child_stack % 16);
+  // Minimum frame size.
+#ifdef __s390x__
+  child_stack = (char *)child_stack - 160;
+#else
+  child_stack = (char *)child_stack - 96;
+#endif
+  // Terminate unwind chain.
+  ((unsigned long *)child_stack)[0] = 0;
+  // And pass parameters.
+  ((unsigned long *)child_stack)[1] = (uptr)fn;
+  ((unsigned long *)child_stack)[2] = (uptr)arg;
+  register long res __asm__("r2");
+  register void *__cstack      __asm__("r2") = child_stack;
+  register int __flags         __asm__("r3") = flags;
+  register int * __ptidptr     __asm__("r4") = parent_tidptr;
+  register int * __ctidptr     __asm__("r5") = child_tidptr;
+  register void * __newtls     __asm__("r6") = newtls;
+
+  __asm__ __volatile__(
+                       /* Clone. */
+                       "svc    %1\n"
+
+                       /* if (%r2 != 0)
+                        *   return;
+                        */
+#ifdef __s390x__
+                       "cghi   %%r2, 0\n"
+#else
+                       "chi    %%r2, 0\n"
+#endif
+                       "jne    1f\n"
+
+                       /* Call "fn(arg)". */
+#ifdef __s390x__
+                       "lmg    %%r1, %%r2, 8(%%r15)\n"
+#else
+                       "lm     %%r1, %%r2, 4(%%r15)\n"
+#endif
+                       "basr   %%r14, %%r1\n"
+
+                       /* Call _exit(%r2). */
+                       "svc %2\n"
+
+                       /* Return to parent. */
+                     "1:\n"
+                       : "=r" (res)
+                       : "i"(__NR_clone), "i"(__NR_exit),
+                         "r"(__cstack),
+                         "r"(__flags),
+                         "r"(__ptidptr),
+                         "r"(__ctidptr),
+                         "r"(__newtls)
+                       : "memory", "cc");
+  return res;
+}
+
 } // namespace __sanitizer
 
 #endif // SANITIZER_LINUX && SANITIZER_S390