adjust cfi expressions to use the correct parent_ctx offset

the struct at rbp changed between first authorship and today, to fix a bug where lucet instances were accidentally tied to their starting thread

Author: iximeow

lucet-runtime/lucet-runtime-internals/src/context/context_asm.S

@@ -92,8 +92,8 @@ _unwind_stub:
     // able to figure this out based on the saved rsp value, things go wrong if this is missing.
 
     .cfi_escape 0x0f, /* DW_CFA_def_cfa_expression */ \
-                8, /* uleb128 length of expression bytes */ \
-                0x76, 0x18, /* DW_OP_breg5 (put rbp + 24 on the stack; should be a pointer to the parent context's address) */ \
+                9, /* uleb128 length of expression bytes */ \
+                0x76, 0xf0, 0x01, /* DW_OP_breg5 (put rbp + 240 on the stack; should be a pointer to the parent context's address) */ \
                 0x06, /* DW_OP_deref should then leave the parent context pointer on the stack */ \
                 0x23, 0x08, /* DW_OP_plus_uconst (add 8 to the base of context to point to saved rsp) */ \
                 0x06, /* deref */ \
@@ -104,8 +104,8 @@ _unwind_stub:
     // the extra `lucet_context_swap` call frame we want to skip over
 
     .cfi_escape 0x16, 0x07, /* DW_CFA_val_expression(7=rsp) */ \
-                8, /* uleb128 length of expression bytes */ \
-                0x76, 0x18, /* DW_OP_breg5 (put rbp + 24 on the stack; should be a pointer to the parent context's address) */ \
+                9, /* uleb128 length of expression bytes */ \
+                0x76, 0xf0, 0x01, /* DW_OP_breg5 (put rbp + 240 on the stack; should be a pointer to the parent context's address) */ \
                 0x06, /* DW_OP_deref should then leave the parent context pointer on the stack */ \
                 0x23, 0x08, /* DW_OP_plus_uconst (add 8 to the base of context to point to saved rsp) */ \
                 0x06, /* deref */ \
@@ -115,44 +115,44 @@ _unwind_stub:
     // the corresponding field on the `Context` struct
 
     .cfi_escape 0x10, 0x03, /* DW_CFA_expression(3=rbx) */ \
-                3, /* uleb128 length of expression bytes */ \
-                0x76, 0x18, /* DW_OP_breg5 (put rbp + 24 on the stack; should be a pointer to the parent context's address) */ \
+                4, /* uleb128 length of expression bytes */ \
+                0x76, 0xf0, 0x01, /* DW_OP_breg5 (put rbp + 240 on the stack; should be a pointer to the parent context's address) */ \
                 0x06 /* DW_OP_deref should then leave the parent context pointer on the stack */ \
                 /* rbx is at offset 0 */
 
     .cfi_escape 0x10, 0x06, /* DW_CFA_expression(6=rbp) */ \
-                5, /* uleb128 length of expression bytes */ \
-                0x76, 0x18, /* DW_OP_breg5 (put rbp + 24 on the stack; should be a pointer to the parent context's address) */ \
+                6, /* uleb128 length of expression bytes */ \
+                0x76, 0xf0, 0x01, /* DW_OP_breg5 (put rbp + 240 on the stack; should be a pointer to the parent context's address) */ \
                 0x06, /* DW_OP_deref should then leave the parent context pointer on the stack */ \
                 0x23, 0x10 /* DW_OP_plus_uconst (add 16 to the base of context to point to saved rbp) */
 
     .cfi_escape 0x10, 0x05, /* DW_CFA_expression(5=rdi) */ \
-                5, /* uleb128 length of expression bytes */ \
-                0x76, 0x18, /* DW_OP_breg5 (put rbp + 24 on the stack; should be a pointer to the parent context's address) */ \
+                6, /* uleb128 length of expression bytes */ \
+                0x76, 0xf0, 0x01, /* DW_OP_breg5 (put rbp + 240 on the stack; should be a pointer to the parent context's address) */ \
                 0x06, /* DW_OP_deref should then leave the parent context pointer on the stack */ \
                 0x23, 0x18 /* DW_OP_plus_uconst (add 24 to the base of context to point to saved rdi) */
 
     .cfi_escape 0x10, 0x0c, /* DW_CFA_expression(12=r12) */ \
-                5, /* uleb128 length of expression bytes */ \
-                0x76, 0x18, /* DW_OP_breg5 (put rbp + 24 on the stack; should be a pointer to the parent context's address) */ \
+                6, /* uleb128 length of expression bytes */ \
+                0x76, 0xf0, 0x01, /* DW_OP_breg5 (put rbp + 240 on the stack; should be a pointer to the parent context's address) */ \
                 0x06, /* DW_OP_deref should then leave the parent context pointer on the stack */ \
                 0x23, 0x20 /* DW_OP_plus_uconst (add 32 to the base of context to point to saved r12) */
 
     .cfi_escape 0x10, 0x0d, /* DW_CFA_expression(13=r13) */ \
-                5, /* uleb128 length of expression bytes */ \
-                0x76, 0x18, /* DW_OP_breg5 (put rbp + 24 on the stack; should be a pointer to the parent context's address) */ \
+                6, /* uleb128 length of expression bytes */ \
+                0x76, 0xf0, 0x01, /* DW_OP_breg5 (put rbp + 240 on the stack; should be a pointer to the parent context's address) */ \
                 0x06, /* DW_OP_deref should then leave the parent context pointer on the stack */ \
                 0x23, 0x28 /* DW_OP_plus_uconst (add 40 to the base of context to point to saved r13) */
 
     .cfi_escape 0x10, 0x0e, /* DW_CFA_expression(14=r14) */ \
-                5, /* uleb128 length of expression bytes */ \
-                0x76, 0x18, /* DW_OP_breg5 (put rbp + 24 on the stack; should be a pointer to the parent context's address) */ \
+                6, /* uleb128 length of expression bytes */ \
+                0x76, 0xf0, 0x01, /* DW_OP_breg5 (put rbp + 240 on the stack; should be a pointer to the parent context's address) */ \
                 0x06, /* DW_OP_deref should then leave the parent context pointer on the stack */ \
                 0x23, 0x30 /* DW_OP_plus_uconst (add 48 to the base of context to point to saved r14) */
 
     .cfi_escape 0x10, 0x0f, /* DW_CFA_expression(15=r15) */ \
-                5, /* uleb128 length of expression bytes */ \
-                0x76, 0x18, /* DW_OP_breg5 (put rbp + 24 on the stack; should be a pointer to the parent context's address) */ \
+                6, /* uleb128 length of expression bytes */ \
+                0x76, 0xf0, 0x01, /* DW_OP_breg5 (put rbp + 240 on the stack; should be a pointer to the parent context's address) */ \
                 0x06, /* DW_OP_deref should then leave the parent context pointer on the stack */ \
                 0x23, 0x38 /* DW_OP_plus_uconst (add 56 to the base of context to point to saved r15) */