Implement setjmp / longjmp in jerry-libc.

JerryScript-DCO-1.0-Signed-off-by: Ruben Ayrapetyan r.ayrapetyan@samsung.com

jerry-libc/arch/x86-64.h

@@ -64,6 +64,17 @@
   syscall; \
   ret;
 
+/*
+ * mov argc ([%rsp]) -> %rdi
+ * mov argv (%rsp + 0x8) -> %rsi
+ *
+ * call main
+ *
+ * mov main_ret (%rax) -> %rdi
+ * call exit
+ *
+ * infinite loop
+ */
 #define _START            \
    mov (%rsp), %rdi;      \
    mov %rsp, %rsi;        \
@@ -71,8 +82,107 @@
    callq main;            \
                           \
    mov %rax, %rdi;        \
-   callq exit;          \
+   callq exit;            \
    1:                     \
    jmp 1b
 
+/*
+ * setjmp
+ *
+ * According to x86_64 System V ABI, the following registers are
+ * callee-saved, and so need to be stored in context:
+ *   - %rbp
+ *   - %rbx
+ *   - %r12
+ *   - %r13
+ *   - %r14
+ *   - %r15
+ *   - x87 control word
+ *
+ * Also, we should store:
+ *   - %rsp (stack pointer)
+ *   - return address (to jump to upon longjmp)
+ *
+ * mov return_address ([%rsp]) -> %rax
+ *
+ * mov %rsp -> jmp_buf_0  ([%rdi + 0x0])
+ * mov %rax -> jmp_buf_8  ([%rdi + 0x8])
+ * mov %rbp -> jmp_buf_16 ([%rdi + 0x10])
+ * mov %rbx -> jmp_buf_24 ([%rdi + 0x18])
+ * mov %r12 -> jmp_buf_32 ([%rdi + 0x20])
+ * mov %r13 -> jmp_buf_40 ([%rdi + 0x28])
+ * mov %r14 -> jmp_buf_48 ([%rdi + 0x30])
+ * mov %r15 -> jmp_buf_56 ([%rdi + 0x38])
+ * fnstcw   -> jmp_buf_64 ([%rdi + 0x40])
+ *
+ * ret
+ */
+#define _SETJMP \
+  mov (%rsp), %rax;      \
+                         \
+  mov %rsp, 0x00(%rdi);  \
+  mov %rax, 0x08(%rdi);  \
+  mov %rbp, 0x10(%rdi);  \
+  mov %rbx, 0x18(%rdi);  \
+  mov %r12, 0x20(%rdi);  \
+  mov %r13, 0x28(%rdi);  \
+  mov %r14, 0x30(%rdi);  \
+  mov %r15, 0x38(%rdi);  \
+  fnstcw 0x40(%rdi);     \
+                         \
+  xor %rax, %rax;        \
+                         \
+  ret;
+
+/*
+ * longjmp
+ *
+ * See also:
+ *          _SETJMP
+ *
+ * mov jmp_buf_0  ([%rdi + 0x0])  -> %rsp
+ * mov jmp_buf_8  ([%rdi + 0x8])  -> %rax
+ * mov jmp_buf_16 ([%rdi + 0x10]) -> %rbp
+ * mov jmp_buf_24 ([%rdi + 0x18]) -> %rbx
+ * mov jmp_buf_32 ([%rdi + 0x20]) -> %r12
+ * mov jmp_buf_40 ([%rdi + 0x28]) -> %r13
+ * mov jmp_buf_48 ([%rdi + 0x30]) -> %r14
+ * mov jmp_buf_56 ([%rdi + 0x38]) -> %r15
+ * fldcw jmp_buf_64 ([%rdi + 0x40])
+ *
+ * mov return_address (%rax) -> ([%rsp])
+ *
+ * mov val (%rsi) -> %rax
+ *
+ * test (%rax), (%rax)
+ * jnz 1f
+ * mov $1, %rax
+ * 1:
+ *
+ * ret
+ */
+#define _LONGJMP \
+  mov 0x00(%rdi), %rsp; \
+  mov 0x08(%rdi), %rax; \
+  mov 0x10(%rdi), %rbp; \
+  mov 0x18(%rdi), %rbx; \
+  mov 0x20(%rdi), %r12; \
+  mov 0x28(%rdi), %r13; \
+  mov 0x30(%rdi), %r14; \
+  mov 0x38(%rdi), %r15; \
+  fldcw 0x40(%rdi);     \
+                        \
+  mov %rax, (%rsp);     \
+                        \
+  mov %rsi, %rax;       \
+                        \
+  test %rax, %rax;      \
+  jnz 1f;               \
+  mov $1, %rax;         \
+ 1:                     \
+                        \
+  ret
+
+
+
 #endif /* !ASM_X64_H */