X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fruntime%2Fx86-64-assem.S;h=053167e076520dcb3b02a1e691ad06d9b2ae59c6;hb=2f9585060d5fe2c525955d80f34123761ded80fe;hp=52321bf9c98263886844f869d0dfcedcb3de51ab;hpb=7cee2468541aafc13ace8a943205572dd0cb7958;p=sbcl.git

diff --git a/src/runtime/x86-64-assem.S b/src/runtime/x86-64-assem.S
index 52321bf..053167e 100644
--- a/src/runtime/x86-64-assem.S
+++ b/src/runtime/x86-64-assem.S
@@ -38,10 +38,12 @@
 #define align_8byte	8
 #define align_16byte	16
 #define align_32byte	32
+#define align_page	32768
 #else
 #define	align_4byte	2
 #define	align_8byte	3
 #define	align_16byte	4	
+#define	align_page	15
 #endif			
 
 /*
@@ -275,6 +277,9 @@ GNAME(undefined_tramp):
 	ret
 	SIZE(GNAME(undefined_tramp))
 
+/* KLUDGE: FIND-ESCAPED-FRAME (SYS:SRC;CODE;DEBUG-INT.LISP) needs
+ * to know the name of the function immediately following the
+ * undefined-function trampoline. */
 
 	.text
 	.align	align_16byte,0x90
@@ -344,6 +349,12 @@ GNAME(closure_tramp):
 /*
  * fun-end breakpoint magic
  */
+
+/*
+ * For an explanation of the magic involved in function-end
+ * breakpoints, see the implementation in ppc-assem.S.
+ */
+
 	.text
 	.globl 	GNAME(fun_end_breakpoint_guts)
 	.align	align_16byte
@@ -452,4 +463,78 @@ Lend:
 	ret
 	SIZE(GNAME(fast_bzero))
 
+
+/* When LISP_FEATURE_C_STACK_IS_CONTROL_STACK, we cannot safely scrub
+ * the control stack from C, largely due to not knowing where the
+ * active stack frame ends.  On such platforms, we reimplement the
+ * core scrubbing logic in assembly, in this case here:
+ */
+	.text
+	.align	align_16byte,0x90
+	.globl GNAME(arch_scrub_control_stack)
+	TYPE(GNAME(arch_scrub_control_stack))
+GNAME(arch_scrub_control_stack):
+	/* We are passed three parameters:
+	 * A (struct thread *) in RDI,
+	 * the address of the guard page in RSI, and
+	 * the address of the hard guard page in RDX.
+	 * We may trash RAX, RCX, and R8-R11 with impunity.
+	 * [RSP] is our return address, [RSP-8] is the first
+	 * stack slot to scrub. */
+
+	/* We start by setting up our scrub pointer in RAX, our
+	 * guard page upper bound in R8, and our hard guard
+	 * page upper bound in R9. */
+	lea	-8(%rsp), %rax
+#ifdef LISP_FEATURE_DARWIN
+	mov	GSYM(GNAME(os_vm_page_size)),%r9
+#else
+	mov	os_vm_page_size,%r9
+#endif
+	lea	(%rsi,%r9), %r8
+	lea	(%rdx,%r9), %r9
+
+	/* Now we begin our main scrub loop. */
+ascs_outer_loop:
+
+	/* If we're about to scrub the hard guard page, exit. */
+	cmp	%r9, %rax
+	jae	ascs_check_guard_page
+	cmp	%rax, %rdx
+	jbe	ascs_finished
+
+ascs_check_guard_page:
+	/* If we're about to scrub the guard page, and the guard
+	 * page is protected, exit. */
+	cmp	%r8, %rax
+	jae	ascs_clear_loop
+	cmp	%rax, %rsi
+	ja	ascs_clear_loop
+	cmpq	$(NIL), THREAD_CONTROL_STACK_GUARD_PAGE_PROTECTED_OFFSET(%rdi)
+	jne	ascs_finished
+
+	/* Clear memory backwards to the start of the (4KiB) page */
+ascs_clear_loop:
+	movq	$0, (%rax)
+	test	$0xfff, %rax
+	lea	-8(%rax), %rax
+	jnz	ascs_clear_loop
+
+	/* If we're about to hit the hard guard page, exit. */
+	cmp	%r9, %rax
+	jae	ascs_finished
+
+	/* If the next (previous?) 4KiB page contains a non-zero
+	 * word, continue scrubbing. */
+ascs_check_loop:
+	testq	$-1, (%rax)
+	jnz	ascs_outer_loop
+	test	$0xfff, %rax
+	lea	-8(%rax), %rax
+	jnz	ascs_check_loop
+
+ascs_finished:
+	ret
+	SIZE(GNAME(arch_scrub_control_stack))
+
         END()