Prologue fix

Author: Blackhex

winsup/cygwin/scripts/gendef

@@ -442,8 +442,11 @@ _ZN7_cygtls6lockedEv:
 
 	.seh_proc stabilize_sig_stack
 stabilize_sig_stack:
+	// prologue
 	stp	fp, lr, [sp, #-16]!		// save FP and LR registers
+	mov	fp, sp				// set FP to current SP
 	sub	sp, sp, #32			// allocate 32 bytes on stack
+
 	.seh_stackalloc 32
 	.seh_endprologue
 	ldr	x10, [x18, #0x8]		// get thread local storage pointer
@@ -499,6 +502,8 @@ stabilize_sig_stack:
 
 	add	sp, sp, #32			// restore stack
 	mov	x1, x10				// return TLS address in x0 (return value)
+
+	// epilogue
 	ldp	fp, lr, [sp], #16		// restore saved FP and LR registers
 	ret
 	.seh_endproc
@@ -653,8 +658,11 @@ sigsetjmp:
 	.globl  setjmp
 	.seh_proc setjmp
 setjmp:
+	// prologue
 	stp	fp, lr, [sp, #-16]!		// save FP and LR registers
+	mov	fp, sp				// set FP to current SP
 	sub	sp, sp, #32			// allocate 32 bytes on stack
+
 	.seh_stackalloc 32
 	.seh_endprologue
 	stp	x19, x20, [x0, #0x08]		// save x19 and x20 to jmp_buf
@@ -692,6 +700,8 @@ setjmp:
 
 	add	sp, sp, #32			// restore stack
 	mov	w0, #0				// return 0
+
+	// epilogue
 	ldp	fp, lr, [sp], #16		// restore saved FP and LR registers
 	ret
 	.seh_endproc