segfault handler, op parser

[ginge.git] / loader / patches.c

diff --git a/loader/patches.c b/loader/patches.c
new file mode 100644 (file)
index 0000000..9354d2f
--- /dev/null
+++ b/loader/patches.c
@@ -0,0 +1,96 @@
+// vim:shiftwidth=2:expandtab
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+
+#include "header.h"
+#include "sys_cacheflush.h"
+
+static const unsigned int sig_open[] = {
+  0xe59cc000, 0xe33c0000, 0x1a000003, 0xef900005
+};
+
+static const unsigned int sig_mmap[] = {
+  0xe92d000f, 0xe1a0000d, 0xef90005a, 0xe28dd010
+};
+
+static const unsigned int sig_mmap_[] = {
+  0xe52d5004, 0xe59d5008, 0xe52d4004, 0xe59d4008,
+  0xe1b0ca05, 0x1a000006, 0xe1a05625, 0xef9000c0
+};
+
+#define FAKE_DEVMEM_DEVICE 10001
+
+static int w_open(const char *pathname, int flags, mode_t mode)
+{
+  int ret;
+  if (strcmp(pathname, "/dev/mem") != 0)
+    ret = open(pathname, flags, mode);
+  else
+    ret = FAKE_DEVMEM_DEVICE;
+
+  printf("open(%s) = %d\n", pathname, ret);
+  return ret;
+}
+
+static void *w_mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
+{
+  void *ret;
+  if (fd != FAKE_DEVMEM_DEVICE)
+    ret = mmap(addr, length, prot, flags, fd, offset);
+  else
+    ret = emu_mmap_dev(length, prot, flags, offset);
+
+  printf("mmap(%p, %x, %x, %x, %d, %lx) = %p\n", addr, length, prot, flags, fd, (long)offset, ret);
+  return ret;
+}
+#define w_mmap_ w_mmap
+
+#define PATCH(f) { sig_##f, ARRAY_SIZE(sig_##f), w_##f }
+
+static const struct {
+  const unsigned int *sig;
+  size_t sig_cnt;
+  void *func;
+} patches[] = {
+  PATCH(open),
+  PATCH(mmap),
+  PATCH(mmap_), // mmap using mmap2 syscall
+};
+
+void do_patches(void *ptr, unsigned int size)
+{
+  int i, s;
+
+  for (i = 0; i < ARRAY_SIZE(patches); i++) {
+    const unsigned int *sig = patches[i].sig;
+    unsigned int *seg = (void *)(((long)ptr + 3) & ~3);
+    unsigned int *seg_end = seg + size / 4;
+    unsigned int sig0 = sig[0];
+
+    for (; seg < seg_end; seg++) {
+      if (*seg != sig0)
+        continue;
+
+      for (s = 1; s < patches[i].sig_cnt; s++)
+        if (seg[s] != sig[s])
+          break;
+
+      if (s == patches[i].sig_cnt)
+        goto found;
+    }
+    continue;
+
+found:
+    printf("  patch #%i @ %08x\n", i, (int)seg);
+    seg[0] = 0xe59ff000; // ldr pc, [pc]
+    seg[1] = 0;
+    seg[2] = (unsigned int)patches[i].func;
+  }
+
+  sys_cacheflush(ptr, (char *)ptr + size);
+}
+