Clean up some code

- Use good ELF technique in cosmo_dlopen()
- Make strerror() conform more to other libc impls
- Introduce __clear_cache() and use it in cosmo_dlopen()
- Remove libc/fmt/fmt.h header (trying to kill off LIBC_FMT)

third_party/compiler_rt/clear_cache.c

@@ -0,0 +1,148 @@
+//===-- clear_cache.c - Implement __clear_cache ---------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include <assert.h>
+#include <stddef.h>
+#include "int_lib.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(__arm__)
+// clang-format off
+#include <sys/types.h>
+#include <machine/sysarch.h>
+// clang-format on
+#endif
+
+#if defined(__NetBSD__) && defined(__arm__)
+#include <machine/sysarch.h>
+#endif
+
+#if defined(__OpenBSD__) && defined(__mips__)
+// clang-format off
+#include <sys/types.h>
+#include <machine/sysarch.h>
+// clang-format on
+#endif
+
+#if defined(__linux__) && defined(__mips__)
+#include <sys/cachectl.h>
+#include <sys/syscall.h>
+#include <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__ || defined(_M_IX86) || defined(_M_X64)
+// Intel processors have a unified instruction and data cache
+// so there is nothing to do
+#elif defined(_WIN32) && (defined(__arm__) || defined(__aarch64__))
+  FlushInstructionCache(GetCurrentProcess(), start, end - start);
+#elif defined(__arm__) && !defined(__APPLE__)
+#if defined(__FreeBSD__) || defined(__NetBSD__)
+  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__)
+// We used to include asm/unistd.h for the __ARM_NR_cacheflush define, but
+// it also brought many other unused defines, as well as a dependency on
+// kernel headers to be installed.
+//
+// This value is stable at least since Linux 3.13 and should remain so for
+// compatibility reasons, warranting it's re-definition here.
+#define __ARM_NR_cacheflush 0x0f0002
+  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));
+  assert(start_reg == 0 && "Cache flush syscall failed.");
+#else
+  compilerrt_abort();
+#endif
+#elif defined(__linux__) && defined(__mips__)
+  const uintptr_t start_int = (uintptr_t)start;
+  const uintptr_t end_int = (uintptr_t)end;
+  syscall(__NR_cacheflush, start, (end_int - start_int), BCACHE);
+#elif defined(__mips__) && defined(__OpenBSD__)
+  cacheflush(start, (uintptr_t)end - (uintptr_t)start, BCACHE);
+#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 & ~(dcache_line_size - 1); 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 & ~(icache_line_size - 1); addr < xend;
+       addr += icache_line_size)
+    __asm __volatile("ic ivau, %0" ::"r"(addr));
+  __asm __volatile("isb sy");
+#elif defined(__powerpc64__)
+  const size_t line_size = 32;
+  const size_t len = (uintptr_t)end - (uintptr_t)start;
+
+  const uintptr_t mask = ~(line_size - 1);
+  const uintptr_t start_line = ((uintptr_t)start) & mask;
+  const uintptr_t end_line = ((uintptr_t)start + len + line_size - 1) & mask;
+
+  for (uintptr_t line = start_line; line < end_line; line += line_size)
+    __asm__ volatile("dcbf 0, %0" : : "r"(line));
+  __asm__ volatile("sync");
+
+  for (uintptr_t line = start_line; line < end_line; line += line_size)
+    __asm__ volatile("icbi 0, %0" : : "r"(line));
+  __asm__ volatile("isync");
+#elif defined(__sparc__)
+  const size_t dword_size = 8;
+  const size_t len = (uintptr_t)end - (uintptr_t)start;
+
+  const uintptr_t mask = ~(dword_size - 1);
+  const uintptr_t start_dword = ((uintptr_t)start) & mask;
+  const uintptr_t end_dword = ((uintptr_t)start + len + dword_size - 1) & mask;
+
+  for (uintptr_t dword = start_dword; dword < end_dword; dword += dword_size)
+    __asm__ volatile("flush %0" : : "r"(dword));
+#else
+#if __APPLE__
+  // On Darwin, sys_icache_invalidate() provides this functionality
+  sys_icache_invalidate(start, end - start);
+#else
+  compilerrt_abort();
+#endif
+#endif
+}