path: root/js/src/jit/arm/Architecture-arm.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=8 sts=2 et sw=2 tw=80:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "jit/arm/Architecture-arm.h"

#if !defined(JS_SIMULATOR_ARM) && !defined(__APPLE__)
#  include <elf.h>
#endif

#include <fcntl.h>
#ifdef XP_UNIX
#  include <unistd.h>
#endif

#if defined(XP_IOS)
#  include <libkern/OSCacheControl.h>
#endif

#include "jit/arm/Assembler-arm.h"
#include "jit/arm/Simulator-arm.h"
#include "jit/FlushICache.h"  // js::jit::FlushICache
#include "jit/RegisterSets.h"

#if !defined(__linux__) || defined(ANDROID) || defined(JS_SIMULATOR_ARM)
// The Android NDK and B2G do not include the hwcap.h kernel header, and it is
// not defined when building the simulator, so inline the header defines we
// need.
#  define HWCAP_VFP (1 << 6)
#  define HWCAP_NEON (1 << 12)
#  define HWCAP_VFPv3 (1 << 13)
#  define HWCAP_VFPv3D16 (1 << 14) /* also set for VFPv4-D16 */
#  define HWCAP_VFPv4 (1 << 16)
#  define HWCAP_IDIVA (1 << 17)
#  define HWCAP_IDIVT (1 << 18)
#  define HWCAP_VFPD32 (1 << 19) /* set if VFP has 32 regs (not 16) */
#  define AT_HWCAP 16
#else
#  include <asm/hwcap.h>
#  if !defined(HWCAP_IDIVA)
#    define HWCAP_IDIVA (1 << 17)
#  endif
#  if !defined(HWCAP_VFPD32)
#    define HWCAP_VFPD32 (1 << 19) /* set if VFP has 32 regs (not 16) */
#  endif
#endif

namespace js {
namespace jit {

// Parse the Linux kernel cpuinfo features. This is also used to parse the
// override features which has some extensions: 'armv7', 'align' and 'hardfp'.
static uint32_t ParseARMCpuFeatures(const char* features,
                                    bool override = false) {
  uint32_t flags = 0;

  // For ease of running tests we want it to be the default to fixup faults.
  bool fixupAlignmentFault = true;

  for (;;) {
    char ch = *features;
    if (!ch) {
      // End of string.
      break;
    }
    if (ch == ' ' || ch == ',') {
      // Skip separator characters.
      features++;
      continue;
    }
    // Find the end of the token.
    const char* end = features + 1;
    for (;; end++) {
      ch = *end;
      if (!ch || ch == ' ' || ch == ',') {
        break;
      }
    }
    size_t count = end - features;
    if (count == 3 && strncmp(features, "vfp", 3) == 0) {
      flags |= HWCAP_VFP;
    } else if (count == 5 && strncmp(features, "vfpv2", 5) == 0) {
      flags |= HWCAP_VFP;  // vfpv2 is the same as vfp
    } else if (count == 4 && strncmp(features, "neon", 4) == 0) {
      flags |= HWCAP_NEON;
    } else if (count == 5 && strncmp(features, "vfpv3", 5) == 0) {
      flags |= HWCAP_VFPv3;
    } else if (count == 8 && strncmp(features, "vfpv3d16", 8) == 0) {
      flags |= HWCAP_VFPv3D16;
    } else if (count == 5 && strncmp(features, "vfpv4", 5) == 0) {
      flags |= HWCAP_VFPv4;
    } else if (count == 5 && strncmp(features, "idiva", 5) == 0) {
      flags |= HWCAP_IDIVA;
    } else if (count == 5 && strncmp(features, "idivt", 5) == 0) {
      flags |= HWCAP_IDIVT;
    } else if (count == 6 && strncmp(features, "vfpd32", 6) == 0) {
      flags |= HWCAP_VFPD32;
    } else if (count == 5 && strncmp(features, "armv7", 5) == 0) {
      flags |= HWCAP_ARMv7;
    } else if (count == 5 && strncmp(features, "align", 5) == 0) {
      flags |= HWCAP_ALIGNMENT_FAULT | HWCAP_FIXUP_FAULT;
#if defined(JS_SIMULATOR_ARM)
    } else if (count == 7 && strncmp(features, "nofixup", 7) == 0) {
      fixupAlignmentFault = false;
    } else if (count == 6 && strncmp(features, "hardfp", 6) == 0) {
      flags |= HWCAP_USE_HARDFP_ABI;
#endif
    } else if (override) {
      fprintf(stderr, "Warning: unexpected ARM feature at: %s\n", features);
    }
    features = end;
  }

  if (!fixupAlignmentFault) {
    flags &= ~HWCAP_FIXUP_FAULT;
  }

  return flags;
}

static uint32_t CanonicalizeARMHwCapFlags(uint32_t flags) {
  // Canonicalize the flags. These rules are also applied to the features
  // supplied for simulation.

  // VFPv3 is a subset of VFPv4, force this if the input string omits it.
  if (flags & HWCAP_VFPv4) {
    flags |= HWCAP_VFPv3;
  }

  // The VFPv3 feature is expected when the VFPv3D16 is reported, but add it
  // just in case of a kernel difference in feature reporting.
  if (flags & HWCAP_VFPv3D16) {
    flags |= HWCAP_VFPv3;
  }

  // VFPv2 is a subset of VFPv3, force this if the input string omits it.  VFPv2
  // is just an alias for VFP.
  if (flags & HWCAP_VFPv3) {
    flags |= HWCAP_VFP;
  }

  // If we have Neon we have floating point.
  if (flags & HWCAP_NEON) {
    flags |= HWCAP_VFP;
  }

  // If VFPv3 or Neon is supported then this must be an ARMv7.
  if (flags & (HWCAP_VFPv3 | HWCAP_NEON)) {
    flags |= HWCAP_ARMv7;
  }

  // Some old kernels report VFP and not VFPv3, but if ARMv7 then it must be
  // VFPv3.
  if ((flags & HWCAP_VFP) && (flags & HWCAP_ARMv7)) {
    flags |= HWCAP_VFPv3;
  }

  // Older kernels do not implement the HWCAP_VFPD32 flag.
  if ((flags & HWCAP_VFPv3) && !(flags & HWCAP_VFPv3D16)) {
    flags |= HWCAP_VFPD32;
  }

  return flags;
}

#if !defined(JS_SIMULATOR_ARM) && (defined(__linux__) || defined(ANDROID))
static bool forceDoubleCacheFlush = false;
#endif

// The override flags parsed from the ARMHWCAP environment variable or from the
// --arm-hwcap js shell argument.  They are stable after startup: there is no
// longer a programmatic way of setting these from JS.
volatile uint32_t armHwCapFlags = HWCAP_UNINITIALIZED;

bool CPUFlagsHaveBeenComputed() { return armHwCapFlags != HWCAP_UNINITIALIZED; }

static const char* gArmHwCapString = nullptr;

void SetARMHwCapFlagsString(const char* armHwCap) {
  MOZ_ASSERT(!CPUFlagsHaveBeenComputed());
  gArmHwCapString = armHwCap;
}

static void ParseARMHwCapFlags(const char* armHwCap) {
  MOZ_ASSERT(armHwCap);

  if (strstr(armHwCap, "help")) {
    fflush(NULL);
    printf(
        "\n"
        "usage: ARMHWCAP=option,option,option,... where options can be:\n"
        "\n"
        "  vfp      \n"
        "  neon     \n"
        "  vfpv3    \n"
        "  vfpv3d16 \n"
        "  vfpv4    \n"
        "  idiva    \n"
        "  idivt    \n"
        "  vfpd32   \n"
        "  armv7    \n"
        "  align    - unaligned accesses will trap and be emulated\n"
#ifdef JS_SIMULATOR_ARM
        "  nofixup  - disable emulation of unaligned accesses\n"
        "  hardfp   \n"
#endif
        "\n");
    exit(0);
    /*NOTREACHED*/
  }

  uint32_t flags = ParseARMCpuFeatures(armHwCap, /* override = */ true);

#ifdef JS_CODEGEN_ARM_HARDFP
  flags |= HWCAP_USE_HARDFP_ABI;
#endif

  armHwCapFlags = CanonicalizeARMHwCapFlags(flags);
  JitSpew(JitSpew_Codegen, "ARM HWCAP: 0x%x\n", armHwCapFlags);
}

void InitARMFlags() {
  MOZ_RELEASE_ASSERT(armHwCapFlags == HWCAP_UNINITIALIZED);

  if (const char* env = getenv("ARMHWCAP")) {
    ParseARMHwCapFlags(env);
    return;
  }

  if (gArmHwCapString) {
    ParseARMHwCapFlags(gArmHwCapString);
    return;
  }

  uint32_t flags = 0;
#ifdef JS_SIMULATOR_ARM
  // HWCAP_FIXUP_FAULT is on by default even if HWCAP_ALIGNMENT_FAULT is
  // not on by default, because some memory access instructions always fault.
  // Notably, this is true for floating point accesses.
  flags = HWCAP_ARMv7 | HWCAP_VFP | HWCAP_VFPv3 | HWCAP_VFPv4 | HWCAP_NEON |
          HWCAP_IDIVA | HWCAP_FIXUP_FAULT;
#else

#  if defined(__linux__) || defined(ANDROID)
  // This includes Android and B2G.
  bool readAuxv = false;
  int fd = open("/proc/self/auxv", O_RDONLY);
  if (fd > 0) {
    struct {
      uint32_t a_type;
      uint32_t a_val;
    } aux;
    while (read(fd, &aux, sizeof(aux))) {
      if (aux.a_type == AT_HWCAP) {
        flags = aux.a_val;
        readAuxv = true;
        break;
      }
    }
    close(fd);
  }

  FILE* fp = fopen("/proc/cpuinfo", "r");
  if (fp) {
    char buf[1024] = {};
    size_t len = fread(buf, sizeof(char), sizeof(buf) - 1, fp);
    fclose(fp);
    buf[len] = '\0';

    // Read the cpuinfo Features if the auxv is not available.
    if (!readAuxv) {
      char* featureList = strstr(buf, "Features");
      if (featureList) {
        if (char* featuresEnd = strstr(featureList, "\n")) {
          *featuresEnd = '\0';
        }
        flags = ParseARMCpuFeatures(featureList + 8);
      }
      if (strstr(buf, "ARMv7")) {
        flags |= HWCAP_ARMv7;
      }
    }

    // The exynos7420 cpu (EU galaxy S6 (Note)) has a bug where sometimes
    // flushing doesn't invalidate the instruction cache. As a result we force
    // it by calling the cacheFlush twice on different start addresses.
    char* exynos7420 = strstr(buf, "Exynos7420");
    if (exynos7420) {
      forceDoubleCacheFlush = true;
    }
  }
#  endif

  // If compiled to use specialized features then these features can be
  // assumed to be present otherwise the compiler would fail to run.

#  ifdef JS_CODEGEN_ARM_HARDFP
  // Compiled to use the hardfp ABI.
  flags |= HWCAP_USE_HARDFP_ABI;
#  endif

#  if defined(__VFP_FP__) && !defined(__SOFTFP__)
  // Compiled to use VFP instructions so assume VFP support.
  flags |= HWCAP_VFP;
#  endif

#  if defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__)
  // Compiled to use ARMv7 instructions so assume the ARMv7 arch.
  flags |= HWCAP_ARMv7;
#  endif

#  if defined(__APPLE__)
#    if defined(__ARM_NEON__)
  flags |= HWCAP_NEON;
#    endif
#    if defined(__ARMVFPV3__)
  flags |= HWCAP_VFPv3 | HWCAP_VFPD32
#    endif
#  endif

#endif  // JS_SIMULATOR_ARM

  armHwCapFlags = CanonicalizeARMHwCapFlags(flags);

  JitSpew(JitSpew_Codegen, "ARM HWCAP: 0x%x\n", armHwCapFlags);
  return;
}

uint32_t GetARMFlags() {
  MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
  return armHwCapFlags;
}

bool HasNEON() {
  MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
  return armHwCapFlags & HWCAP_NEON;
}

bool HasARMv7() {
  MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
  return armHwCapFlags & HWCAP_ARMv7;
}

bool HasMOVWT() {
  MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
  return armHwCapFlags & HWCAP_ARMv7;
}

bool HasLDSTREXBHD() {
  // These are really available from ARMv6K and later, but why bother?
  MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
  return armHwCapFlags & HWCAP_ARMv7;
}

bool HasDMBDSBISB() {
  MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
  return armHwCapFlags & HWCAP_ARMv7;
}

bool HasVFPv3() {
  MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
  return armHwCapFlags & HWCAP_VFPv3;
}

bool HasVFP() {
  MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
  return armHwCapFlags & HWCAP_VFP;
}

bool Has32DP() {
  MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
  return armHwCapFlags & HWCAP_VFPD32;
}

bool HasIDIV() {
  MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
  return armHwCapFlags & HWCAP_IDIVA;
}

// This is defined in the header and inlined when not using the simulator.
#ifdef JS_SIMULATOR_ARM
bool UseHardFpABI() {
  MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
  return armHwCapFlags & HWCAP_USE_HARDFP_ABI;
}
#endif

Registers::Code Registers::FromName(const char* name) {
  // Check for some register aliases first.
  if (strcmp(name, "ip") == 0) {
    return ip;
  }
  if (strcmp(name, "r13") == 0) {
    return r13;
  }
  if (strcmp(name, "lr") == 0) {
    return lr;
  }
  if (strcmp(name, "r15") == 0) {
    return r15;
  }

  for (size_t i = 0; i < Total; i++) {
    if (strcmp(GetName(i), name) == 0) {
      return Code(i);
    }
  }

  return Invalid;
}

FloatRegisters::Code FloatRegisters::FromName(const char* name) {
  for (size_t i = 0; i < TotalSingle; ++i) {
    if (strcmp(GetSingleName(Encoding(i)), name) == 0) {
      return VFPRegister(i, VFPRegister::Single).code();
    }
  }
  for (size_t i = 0; i < TotalDouble; ++i) {
    if (strcmp(GetDoubleName(Encoding(i)), name) == 0) {
      return VFPRegister(i, VFPRegister::Double).code();
    }
  }

  return Invalid;
}

FloatRegisterSet VFPRegister::ReduceSetForPush(const FloatRegisterSet& s) {
#ifdef ENABLE_WASM_SIMD
#  error "Needs more careful logic if SIMD is enabled"
#endif

  LiveFloatRegisterSet mod;
  for (FloatRegisterIterator iter(s); iter.more(); ++iter) {
    if ((*iter).isSingle()) {
      // Add in just this float.
      mod.addUnchecked(*iter);
    } else if ((*iter).id() < 16) {
      // A double with an overlay, add in both floats.
      mod.addUnchecked((*iter).singleOverlay(0));
      mod.addUnchecked((*iter).singleOverlay(1));
    } else {
      // Add in the lone double in the range 16-31.
      mod.addUnchecked(*iter);
    }
  }
  return mod.set();
}

uint32_t VFPRegister::GetPushSizeInBytes(const FloatRegisterSet& s) {
#ifdef ENABLE_WASM_SIMD
#  error "Needs more careful logic if SIMD is enabled"
#endif

  FloatRegisterSet ss = s.reduceSetForPush();
  uint64_t bits = ss.bits();
  uint32_t ret = mozilla::CountPopulation32(bits & 0xffffffff) * sizeof(float);
  ret += mozilla::CountPopulation32(bits >> 32) * sizeof(double);
  return ret;
}
uint32_t VFPRegister::getRegisterDumpOffsetInBytes() {
#ifdef ENABLE_WASM_SIMD
#  error "Needs more careful logic if SIMD is enabled"
#endif

  if (isSingle()) {
    return id() * sizeof(float);
  }
  if (isDouble()) {
    return id() * sizeof(double);
  }
  MOZ_CRASH("not Single or Double");
}

uint32_t FloatRegisters::ActualTotalPhys() {
  if (Has32DP()) {
    return 32;
  }
  return 16;
}

void FlushICache(void* code, size_t size) {
#if defined(JS_SIMULATOR_ARM)
  js::jit::SimulatorProcess::FlushICache(code, size);

#elif (defined(__linux__) || defined(ANDROID)) && defined(__GNUC__)
  void* end = (void*)(reinterpret_cast<char*>(code) + size);
  asm volatile(
      "push    {r7}\n"
      "mov     r0, %0\n"
      "mov     r1, %1\n"
      "mov     r7, #0xf0000\n"
      "add     r7, r7, #0x2\n"
      "mov     r2, #0x0\n"
      "svc     0x0\n"
      "pop     {r7}\n"
      :
      : "r"(code), "r"(end)
      : "r0", "r1", "r2");

  if (forceDoubleCacheFlush) {
    void* start = (void*)((uintptr_t)code + 1);
    asm volatile(
        "push    {r7}\n"
        "mov     r0, %0\n"
        "mov     r1, %1\n"
        "mov     r7, #0xf0000\n"
        "add     r7, r7, #0x2\n"
        "mov     r2, #0x0\n"
        "svc     0x0\n"
        "pop     {r7}\n"
        :
        : "r"(start), "r"(end)
        : "r0", "r1", "r2");
  }

#elif defined(__FreeBSD__) || defined(__NetBSD__)
  __clear_cache(code, reinterpret_cast<char*>(code) + size);

#elif defined(XP_IOS)
  sys_icache_invalidate(code, size);

#else
#  error "Unexpected platform"
#endif
}

void FlushExecutionContext() {
#ifndef JS_SIMULATOR_ARM
  // Ensure that any instructions already in the pipeline are discarded and
  // reloaded from the icache.
  asm volatile("isb\n" : : : "memory");
#else
  // We assume the icache flushing routines on other platforms take care of this
#endif
}

}  // namespace jit
}  // namespace js