Add build system scaffolding and libc headers

1 files changed, 18 insertions, 0 deletions

diff --git a/lib/libc/arch/x86_64/longjmp.c b/lib/libc/arch/x86_64/longjmp.c
new file mode 100644
index 00000000..6aed69a5
--- /dev/null
+++ b/lib/libc/arch/x86_64/longjmp.c
@@ -0,0 +1,18 @@
+#include <setjmp.h>
+
+__attribute__((noreturn, naked, returns_twice)) void longjmp(jmp_buf env,
+							     int val)
+{
+	__asm__ __volatile__("mov 0(%rdi), %rbx\n"
+			     "mov 8(%rdi), %rbp\n"
+			     "mov 16(%rdi), %r12\n"
+			     "mov 24(%rdi), %r13\n"
+			     "mov 32(%rdi), %r14\n"
+			     "mov 40(%rdi), %r15\n"
+			     "mov 48(%rdi), %rsp\n"
+			     "xor %rax, %rax\n"
+			     "cmp $0, %esi\n"
+			     "setne %al\n"
+			     "mov %eax, %eax\n"
+			     "jmp *56(%rdi)\n");
+}