clear_cache.c

/* ===-- clear_cache.c - Implement __clear_cache ---------------------------===
 *
 *                     The LLVM Compiler Infrastructure
 *
 * This file is dual licensed under the MIT and the University of Illinois Open
 * Source Licenses. See LICENSE.TXT for details.
 *
 * ===----------------------------------------------------------------------===
 */

#include "int_lib.h"
#include <stddef.h>

#if __APPLE__
  #include <libkern/OSCacheControl.h>
#endif

#if defined(_WIN32)
/* Forward declare Win32 APIs since the GCC mode driver does not handle the
   newer SDKs as well as needed.  */
uint32_t FlushInstructionCache(uintptr_t hProcess, void *lpBaseAddress,
                               uintptr_t dwSize);
uintptr_t GetCurrentProcess(void);
#endif

#if (defined(__FreeBSD__) || defined(__Bitrig__)) && defined(__arm__)
  #include <sys/types.h>
  #include <machine/sysarch.h>
#endif

#if defined(__NetBSD__) && defined(__arm__)
  #include <machine/sysarch.h>
#endif

#if defined(__mips__)
  #include <sys/cachectl.h>
  #include <sys/syscall.h>
  #include <unistd.h>
  #if defined(__ANDROID__) && defined(__LP64__)
    /*
     * clear_mips_cache - Invalidates instruction cache for Mips.
     */
    static void clear_mips_cache(const void* Addr, size_t Size) {
      asm volatile (
        ".set push\n"
        ".set noreorder\n"
        ".set noat\n"
        "beq %[Size], $zero, 20f\n"          /* If size == 0, branch around. */
        "nop\n"
        "daddu %[Size], %[Addr], %[Size]\n"  /* Calculate end address + 1 */
        "rdhwr $v0, $1\n"                    /* Get step size for SYNCI.
                                                $1 is $HW_SYNCI_Step */
        "beq $v0, $zero, 20f\n"              /* If no caches require
                                                synchronization, branch
                                                around. */
        "nop\n"
        "10:\n"
        "synci 0(%[Addr])\n"                 /* Synchronize all caches around
                                                address. */
        "daddu %[Addr], %[Addr], $v0\n"      /* Add step size. */
        "sltu $at, %[Addr], %[Size]\n"       /* Compare current with end
                                                address. */
        "bne $at, $zero, 10b\n"              /* Branch if more to do. */
        "nop\n"
        "sync\n"                             /* Clear memory hazards. */
        "20:\n"
        "bal 30f\n"
        "nop\n"
        "30:\n"
        "daddiu $ra, $ra, 12\n"              /* $ra has a value of $pc here.
                                                Add offset of 12 to point to the
                                                instruction after the last nop.
                                              */
        "jr.hb $ra\n"                        /* Return, clearing instruction
                                                hazards. */
        "nop\n"
        ".set pop\n"
        : [Addr] "+r"(Addr), [Size] "+r"(Size)
        :: "at", "ra", "v0", "memory"
      );
    }
  #endif
#endif

#if defined(__linux__) && defined(__arm__)
  #include <asm/unistd.h>
#endif

/*
 * The compiler generates calls to __clear_cache() when creating 
 * trampoline functions on the stack for use with nested functions.
 * It is expected to invalidate the instruction cache for the 
 * specified range.
 */

void __clear_cache(void *start, void *end) {
#if __i386__ || __x86_64__
/*
 * Intel processors have a unified instruction and data cache
 * so there is nothing to do
 */
#elif defined(__arm__) && !defined(__APPLE__)
    #if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__Bitrig__)
        struct arm_sync_icache_args arg;

        arg.addr = (uintptr_t)start;
        arg.len = (uintptr_t)end - (uintptr_t)start;

        sysarch(ARM_SYNC_ICACHE, &arg);
    #elif defined(__linux__)
         register int start_reg __asm("r0") = (int) (intptr_t) start;
         const register int end_reg __asm("r1") = (int) (intptr_t) end;
         const register int flags __asm("r2") = 0;
         const register int syscall_nr __asm("r7") = __ARM_NR_cacheflush;
         __asm __volatile("svc 0x0"
                          : "=r"(start_reg)
                          : "r"(syscall_nr), "r"(start_reg), "r"(end_reg),
                            "r"(flags));
         if (start_reg != 0) {
             compilerrt_abort();
         }
    #elif defined(_WIN32)
        FlushInstructionCache(GetCurrentProcess(), start, end - start);
    #else
        compilerrt_abort();
    #endif
#elif defined(__mips__)
  const uintptr_t start_int = (uintptr_t) start;
  const uintptr_t end_int = (uintptr_t) end;
    #if defined(__ANDROID__) && defined(__LP64__)
        // Call synci implementation for short address range.
        const uintptr_t address_range_limit = 256;
        if ((end_int - start_int) <= address_range_limit) {
            clear_mips_cache(start, (end_int - start_int));
        } else {
            syscall(__NR_cacheflush, start, (end_int - start_int), BCACHE);
        }
    #else
        syscall(__NR_cacheflush, start, (end_int - start_int), BCACHE);
    #endif
#elif defined(__aarch64__) && !defined(__APPLE__)
  uint64_t xstart = (uint64_t)(uintptr_t) start;
  uint64_t xend = (uint64_t)(uintptr_t) end;
  uint64_t addr;

  // Get Cache Type Info
  uint64_t ctr_el0;
  __asm __volatile("mrs %0, ctr_el0" : "=r"(ctr_el0));

  /*
   * dc & ic instructions must use 64bit registers so we don't use
   * uintptr_t in case this runs in an IPL32 environment.
   */
  const size_t dcache_line_size = 4 << ((ctr_el0 >> 16) & 15);
  for (addr = xstart; addr < xend; addr += dcache_line_size)
    __asm __volatile("dc cvau, %0" :: "r"(addr));
  __asm __volatile("dsb ish");

  const size_t icache_line_size = 4 << ((ctr_el0 >> 0) & 15);
  for (addr = xstart; addr < xend; addr += icache_line_size)
    __asm __volatile("ic ivau, %0" :: "r"(addr));
  __asm __volatile("isb sy");
#else
    #if __APPLE__
        /* On Darwin, sys_icache_invalidate() provides this functionality */
        sys_icache_invalidate(start, end-start);
    #else
        compilerrt_abort();
    #endif
#endif
}