[metal] Fix argc & argv[] setting, & VM page freeing, for UEFI

Part of the memory occupied by the argv[] contents was
erroneously used for page tables & then later erroneously
freed.  The symptom was that argv[0] would show up as an
empty string ("").

Author: tkchia

libc/runtime/efimain.greg.c

@@ -195,23 +195,23 @@ __msabi EFI_STATUS EfiMain(EFI_HANDLE ImageHandle,
   Address = 0x79000;
   SystemTable->BootServices->AllocatePages(
       AllocateAddress, EfiRuntimeServicesData,
-      (0x7e000 - 0x79000 + sizeof(struct EfiArgs) + 4095) / 4096, &Address);
+      (0x7f000 - 0x79000 + sizeof(struct EfiArgs) + 4095) / 4096, &Address);
   Address = IMAGE_BASE_PHYSICAL;
   SystemTable->BootServices->AllocatePages(
       AllocateAddress, EfiRuntimeServicesData,
       ((_end - __executable_start) + 4095) / 4096, &Address);
   mm = __get_mm_phy();
   SystemTable->BootServices->SetMem(mm, sizeof(*mm), 0);
   SystemTable->BootServices->SetMem(
-      (void *)0x79000, 0x7e000 - 0x79000 + sizeof(struct EfiArgs), 0);
+      (void *)0x79000, 0x7f000 - 0x79000 + sizeof(struct EfiArgs), 0);
   SystemTable->BootServices->CopyMem((void *)IMAGE_BASE_PHYSICAL,
                                      __executable_start,
                                      _end - __executable_start);
 
   /*
    * Converts UEFI shell arguments to argv.
    */
-  ArgBlock = (struct EfiArgs *)0x7e000;
+  ArgBlock = (struct EfiArgs *)0x7f000;
   SystemTable->BootServices->HandleProtocol(ImageHandle,
                                             &kEfiLoadedImageProtocol, &ImgInfo);
   CmdLine = (const char16_t *)ImgInfo->LoadOptions;