Kernel: Add sys$get_stack_bounds() for finding the stack base & size

This will be useful when implementing conservative garbage collection.
cubiclove · Mar 16, 2020 · ad92a1e · ad92a1e
1 parent 086f68e
commit ad92a1e
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Showing 5 changed files with 33 additions and 1 deletion.
diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
@@ -4838,4 +4838,25 @@ OwnPtr<Process::ELFBundle> Process::elf_bundle() const
  return bundle;
 }
 
+int Process::sys$get_stack_bounds(FlatPtr* user_stack_base, size_t* user_stack_size)
+{
+ if (!validate_write_typed(user_stack_base))
+ return -EFAULT;
+ if (!validate_write_typed(user_stack_size))
+ return -EFAULT;
+
+ FlatPtr stack_pointer = Thread::current->get_register_dump_from_stack().userspace_esp;
+ auto* stack_region = MM.region_from_vaddr(*this, VirtualAddress(stack_pointer));
+ if (!stack_region) {
+ ASSERT_NOT_REACHED();
+ return -EINVAL;
+ }
+
+ FlatPtr stack_base = stack_region->range().base().get();
+ size_t stack_size = stack_region->size();
+ copy_to_user(user_stack_base, &stack_base);
+ copy_to_user(user_stack_size, &stack_size);
+ return 0;
+}
+
 }
diff --git a/Kernel/Process.h b/Kernel/Process.h
@@ -298,6 +298,7 @@ class Process : public InlineLinkedListNode<Process> {
  int sys$pledge(const Syscall::SC_pledge_params*);
  int sys$unveil(const Syscall::SC_unveil_params*);
  int sys$perf_event(int type, FlatPtr arg1, FlatPtr arg2);
+ int sys$get_stack_bounds(FlatPtr* stack_base, size_t* stack_size);
 
  template<bool sockname, typename Params>
  int get_sock_or_peer_name(const Params&);

diff --git a/Kernel/Syscall.h b/Kernel/Syscall.h
@@ -178,7 +178,8 @@ namespace Kernel {
  __ENUMERATE_SYSCALL(pledge) \
  __ENUMERATE_SYSCALL(unveil) \
  __ENUMERATE_SYSCALL(perf_event) \
- __ENUMERATE_SYSCALL(shutdown)
+ __ENUMERATE_SYSCALL(shutdown) \
+ __ENUMERATE_SYSCALL(get_stack_bounds)
 
 namespace Syscall {
 

diff --git a/Libraries/LibC/serenity.cpp b/Libraries/LibC/serenity.cpp
@@ -124,4 +124,11 @@ int shbuf_allow_all(int shbuf_id)
  int rc = syscall(SC_shbuf_allow_all, shbuf_id);
  __RETURN_WITH_ERRNO(rc, rc, -1);
 }
+
+int get_stack_bounds(uintptr_t* user_stack_base, size_t* user_stack_size)
+{
+ int rc = syscall(SC_get_stack_bounds, user_stack_base, user_stack_size);
+ __RETURN_WITH_ERRNO(rc, rc, -1);
+}
+
 }
diff --git a/Libraries/LibC/serenity.h b/Libraries/LibC/serenity.h
@@ -68,4 +68,6 @@ int purge(int mode);
 
 int perf_event(int type, uintptr_t arg1, uintptr_t arg2);
 
+int get_stack_bounds(uintptr_t* user_stack_base, size_t* user_stack_size);
+
 __END_DECLS