libplatform-254.40.4.tar.gz

[apple/libplatform.git] / src / setjmp / arm64 / setjmp.s

diff --git a/src/setjmp/arm64/setjmp.s b/src/setjmp/arm64/setjmp.s
index 430b7a98ff6557eda01c2f000012f48623f2492f..02b79bd8c7ca3dcab0297ebf7c1545360cf1f433 100644 (file)
--- a/src/setjmp/arm64/setjmp.s
+++ b/src/setjmp/arm64/setjmp.s
@@ -2,14 +2,14 @@
  * Copyright (c) 2011-2018 Apple Inc. All rights reserved.
  *
  * @APPLE_LICENSE_HEADER_START@
- * 
+ *
  * This file contains Original Code and/or Modifications of Original Code
  * as defined in and that are subject to the Apple Public Source License
  * Version 2.0 (the 'License'). You may not use this file except in
  * compliance with the License. Please obtain a copy of the License at
  * http://www.opensource.apple.com/apsl/ and read it before using this
  * file.
- * 
+ *
  * The Original Code and all software distributed under the License are
  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
@@ -17,7 +17,7 @@
  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  * Please see the License for the specific language governing rights and
  * limitations under the License.
- * 
+ *
  * @APPLE_LICENSE_HEADER_END@
  */
 
@@ -32,8 +32,11 @@
 #define        JMP_d10_d11     #0x80
 #define        JMP_d12_d13     #0x90
 #define        JMP_d14_d15     #0xA0
-#define        JMP_sig         #0xB0
+#define        JMP_sigmask     #0xB0
 #define        JMP_sigflag     #0xB8
+#define        JMP_sigonstack  #0xBC /* whether the thread is on sigaltstack or not */
+
+#define STACK_SSFLAGS  16 // offsetof(stack_t, ss_flags)
 
 #include <architecture/arm/asm_help.h>
 #include <os/tsd.h>
@@ -77,6 +80,7 @@ ENTRY_POINT(__longjmp)
        _OS_PTR_UNMUNGE(fp, x10, x16)
        _OS_PTR_UNMUNGE(lr, x11, x16)
        _OS_PTR_UNMUNGE(x12, x12, x16)
+       ldrb            w16, [sp]       /* probe to detect absolutely corrupt stack pointers */
        mov             sp, x12
        cmp             w1, #0
        csinc   w0, w1, wzr, ne
@@ -92,15 +96,25 @@ ENTRY_POINT(_sigsetjmp)
 
 /* int setjmp(jmp_buf env); */
 ENTRY_POINT(_setjmp)
-       stp             x21, lr, [x0]
-       mov             x21, x0
+       stp             x21, lr, [x0] // Store x21 and lr in jmpbuf (for now)
+       mov             x21, x0           // x21 = x0
 
-       orr             w0, wzr, #0x1
-       mov             x1, #0
-       add             x2, x21, JMP_sig
+       // Save the sigmask
+       orr             w0, wzr, #0x1 // x0 = how = SIG_BLOCK
+       mov             x1, #0            // x1 = set = 0
+       add             x2, x21, JMP_sigmask // x2 = oset = (x21 + JMP_sigmask)
        CALL_EXTERNAL(_sigprocmask)
 
-       mov             x0, x21
+       // Get current sigaltstack status
+       sub             sp, sp, #32 // 24 bytes for a stack_t on the stack, +8 for alignment of stack
+       mov             x0, xzr         // x0 = ss = NULL
+       mov             x1, sp          // x1 = oss = the place on the stack where the stack_t is located
+       CALL_EXTERNAL(___sigaltstack) // sigaltstack(NULL, oss)
+       ldr             w0, [sp, STACK_SSFLAGS] // w0 = ss flags from stack_t
+       str             w0, [x21, JMP_sigonstack] // *(x21 + JMP_sigonstack) = w0
+       add             sp, sp, #32     // Reset sp
+
+       mov             x0, x21         // x0 = x21
        ldp             x21, lr, [x0]
        b               __setjmp
 
@@ -118,12 +132,19 @@ ENTRY_POINT(_longjmp)
        sub     sp, sp, #16
        mov             x21, x0                                 // x21/x22 will be restored by __longjmp
        mov             x22, x1
-       ldr             x8, [x21, JMP_sig]              // restore the signal mask
+
+       // Restore the signal mask
+       ldr             x8, [x21, JMP_sigmask]          // restore the signal mask
        str     x8, [sp, #8]
        orr     w0, wzr, #0x3                   // SIG_SETMASK
        add     x1, sp, #8                              // set
        mov             x2, #0                                  // oset
        CALL_EXTERNAL(_sigprocmask)
+
+       // Restore the sigaltstack status
+       ldr             x0, [x21, JMP_sigonstack] // x0 = saved sigonstack info
+       CALL_EXTERNAL(__sigunaltstack)
+
        mov             x0, x21
        mov             x1, x22
        add     sp, sp, #16