[PowerPC] Fix sanitizers build on FreeBSD

[pkubaj]

Summary

1. Add correct pc, sp and bp for FreeBSD.
2. Since there's no personality.h header on FreeBSD, move SANITIZER_PPC64V2 case below FREEBSD case.
3. __ppc_get_timebase_freq() is glibc-specific. Add a shim for FreeBSD that does the same.

[pkubaj]

Note that __ppc_get_timebase is pretty much copied from glibc (writing it here to make sure that there are no licensing issues).
That said, I don't think there's any other way to read TBR.

[pkubaj]

I followed lint suggestions for SANITIZER_FREEBSD.
As for SANITIZER_PPC64V2 and below, lint seems to be mistaken.

[pkubaj]

ping

[pkubaj]

ping

[pkubaj]

Bring the diff to the current state of sanitizer_linux.cpp and adjust indents to the convention used in the file.

Also drop 32-bit path from xray_powerpc64.inc since the file is for 64-bits.

[nemanjai]

In D116867#3229457, @pkubaj wrote:

Note that __ppc_get_timebase is pretty much copied from glibc (writing it here to make sure that there are no licensing issues).
That said, I don't think there's any other way to read TBR.

Not that there's anything wrong with this implementation (in 64-bit mode), but there is also __builtin_ppc_get_timebase()/__builtin_readcyclecounter().

[pkubaj]

While it probably wouldn't hurt to use compiler builtins, isn't it better to use system-specific functions? They are probably best tailored for specific systems.
Using builtins IMO would be fine as a fallback (for platforms other than Linux with glibc or FreeBSD).

[pkubaj]

I meant this for __ppc_get_timebase_freq, which uses sysctlbyname. __ppc_get_timebase could actually use a builtin.

[pkubaj]

Make __ppc_get_timebase use __builtin_ppc_get_timebase since it's an assembly function anyway.

[pkubaj]

Is there anything I'm doing wrong here?
If not, would it be possible to get this merged? It would be awesome to have this patch merged to 14.0, if possible, as well.

[dim]

I can't vouch for any of the PowerPC specific stuff, but I would like to get it into FreeBSD if at all possible. :)

[adalava]

compiler-rt/lib/xray/xray_powerpc64.inc

23

Looking at https://man7.org/linux/man-pages/man3/__ppc_get_timebase.3.html, this function should return a uint64_t, could you please double check?

[pkubaj]

Change type of __ppc_get_timebase_freq() to uint64_t.

[pkubaj]

Also change the type of tb_freq.

[pkubaj]

Set origin/HEAD as base.

[pkubaj]

compiler-rt/lib/xray/xray_powerpc64.inc

23

Fixed.

[adalava]

It's not actually a problem but tb_freq should be initialized as integer. Otherwise looks good to me!

I validated the code snippet on FreeBSD13/powerpc64 and it's consistent with linux/glibc output on same machine.

compiler-rt/lib/xray/xray_powerpc64.inc

25

uint64_t tb_freq = 0;

[pkubaj]

Actually initialize tb_freq as integer.

[pkubaj]

Removing kcc from reviewers since he seems inactive for the part half a year.
@adalava
As this is now accepted, can you commit it and if possible (since this is a build fix) merge for 14.0.1?

[pkubaj]

Fix clang-format issues.

[nemanjai]

I am not familiar with the FreeBSD-specific stuff, but there is nothing I see any issues with here.
LGTM.

[adalava]

In D116867#3432592, @pkubaj wrote:

Removing kcc from reviewers since he seems inactive for the part half a year.
@adalava
As this is now accepted, can you commit it and if possible (since this is a build fix) merge for 14.0.1?

I'm not a commiter on LLVM side, but @nemanjai or someone else may commit :)

[pkubaj]

@nemanjai
As mentioned by adalava, can you commit this patch?

[nemanjai]

In D116867#3446877, @pkubaj wrote:

@nemanjai
As mentioned by adalava, can you commit this patch?

I will commit this for you tomorrow. Sorry about the delay.

[nemanjai]

Committed in https://reviews.llvm.org/rG315d79213025

I forgot to add the review in the commit message.

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

 //===-- sanitizer_linux.cpp -----------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 //

 #  define REG_UESP 17 // REG_SP
 # endif
 # endif
   *pc = ucontext->uc_mcontext.gregs[REG_EIP];
   *bp = ucontext->uc_mcontext.gregs[REG_EBP];
   *sp = ucontext->uc_mcontext.gregs[REG_UESP];
 # endif
 #elif defined(__powerpc__) || defined(__powerpc64__)
+# if SANITIZER_FREEBSD
+  ucontext_t *ucontext = (ucontext_t*)context;
+  *pc = ucontext->uc_mcontext.mc_srr0;
+  *sp = ucontext->uc_mcontext.mc_frame[1];
+  *bp = ucontext->uc_mcontext.mc_frame[31];
+# else
   ucontext_t *ucontext = (ucontext_t*)context;
   *pc = ucontext->uc_mcontext.regs->nip;
   *sp = ucontext->uc_mcontext.regs->gpr[PT_R1];
   // The powerpc{,64}-linux ABIs do not specify r31 as the frame
   // pointer, but GCC always uses r31 when we need a frame pointer.
   *bp = ucontext->uc_mcontext.regs->gpr[PT_R31];
+#endif
 #elif defined(__sparc__)
 #if defined(__arch64__) || defined(__sparcv9)
 #define STACK_BIAS 2047
 #else
 #define STACK_BIAS 0
 # endif
 # if SANITIZER_SOLARIS
   ucontext_t *ucontext = (ucontext_t *)context;
#if SANITIZER_NETBSD
   }
 
   if (UNLIKELY(paxflags & CTL_PROC_PAXFLAGS_ASLR)) {
     Printf("This sanitizer is not compatible with enabled ASLR.\n"
            "To disable ASLR, please run \"paxctl +a %s\" and try again.\n",
            GetArgv()[0]);
     Die();
   }
-#elif SANITIZER_PPC64V2
-  // Disable ASLR for Linux PPC64LE.
-  int old_personality = personality(0xffffffff);
-  if (old_personality != -1 && (old_personality & ADDR_NO_RANDOMIZE) == 0) {
-    VReport(1, "WARNING: Program is being run with address space layout "
-               "randomization (ASLR) enabled which prevents the thread and "
-               "memory sanitizers from working on powerpc64le.\n"
-               "ASLR will be disabled and the program re-executed.\n");
-    CHECK_NE(personality(old_personality | ADDR_NO_RANDOMIZE), -1);
-    ReExec();
-  }
 #elif SANITIZER_FREEBSD
   int aslr_pie;
   uptr len = sizeof(aslr_pie);
 #if SANITIZER_WORDSIZE == 64
   if (UNLIKELY(internal_sysctlbyname("kern.elf64.aslr.pie_enable",
       &aslr_pie, &len, NULL, 0) == -1)) {
     // We're making things less 'dramatic' here since
     // the OID is not necessarily guaranteed to be here
if (UNLIKELY(internal_sysctlbyname("kern.elf32.aslr.pie_enable",
     return;
   }
 
   if (aslr_pie > 0) {
     Printf("This sanitizer is not compatible with enabled ASLR "
            "and binaries compiled with PIE\n");
     Die();
   }
+#elif SANITIZER_PPC64V2
+  // Disable ASLR for Linux PPC64LE.
+  int old_personality = personality(0xffffffff);
+  if (old_personality != -1 && (old_personality & ADDR_NO_RANDOMIZE) == 0) {
+    VReport(1, "WARNING: Program is being run with address space layout "
+               "randomization (ASLR) enabled which prevents the thread and "
+               "memory sanitizers from working on powerpc64le.\n"
+               "ASLR will be disabled and the program re-executed.\n");
+    CHECK_NE(personality(old_personality | ADDR_NO_RANDOMIZE), -1);
+    ReExec();
+  }
 #else
   // Do nothing
 #endif
 }
 
 void CheckMPROTECT() {
 #if SANITIZER_NETBSD
   int mib[3];
   int paxflags;
   uptr len = sizeof(paxflags);
 

compiler-rt/lib/xray/xray_powerpc64.inc

 //===-- xray_powerpc64.inc --------------------------------------*- 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 is a part of XRay, a dynamic runtime instrumentation system.
 //
 //===----------------------------------------------------------------------===//
 
 #include <cstdint>
 #include <mutex>
+#ifdef __linux__
 #include <sys/platform/ppc.h>
+#elif defined(__FreeBSD__)
+#include <sys/types.h>
+#include <sys/sysctl.h>
+
+static __inline__ uint64_t __ppc_get_timebase (void)
+{
+# ifdef __powerpc64__
+  uint64_t __tb;
+  /* "volatile" is necessary here, because the user expects this assembly
+     isn't moved after an optimization.  */
+  __asm__ volatile ("mfspr %0, 268" : "=r" (__tb));
+  return __tb;
+# else  /* not __powerpc64__ */
+  uint32_t __tbu, __tbl, __tmp; \
+  __asm__ volatile ("0:\n\t"
+        "mftbu %0\n\t"
+        "mftbl %1\n\t"
+        "mftbu %2\n\t"
+        "cmpw %0, %2\n\t"
+        "bne- 0b"
+        : "=r" (__tbu), "=r" (__tbl), "=r" (__tmp));
+  return (((uint64_t) __tbu << 32) | __tbl);
+# endif  /* not __powerpc64__ */
+}
+
+double __ppc_get_timebase_freq (void)
+{
+  double tb_freq = 0.0;
+  size_t length = sizeof(tb_freq);
+  sysctlbyname("kern.timecounter.tc.timebase.frequency", &tb_freq, &length, nullptr, 0);
+  return tb_freq;
+}
+#endif
 
 #include "xray_defs.h"
 
 namespace __xray {
 
 ALWAYS_INLINE uint64_t readTSC(uint8_t &CPU) XRAY_NEVER_INSTRUMENT {
   CPU = 0;
   return __ppc_get_timebase();