path: root/src/thread/arm/syscall_cp.s
diff options
authorRich Felker <>2012-05-23 15:45:41 -0400
committerRich Felker <>2012-05-23 15:45:41 -0400
commit4da268f74b90696563db4f5d9d2b8e1c1351bdc6 (patch)
tree6248d447902f2a011c70e2b207e600718bed77a4 /src/thread/arm/syscall_cp.s
parentcfd892fde9454e014d9b291a56ce5740d8bc4a78 (diff)
fix issue with longjmp out of signal handlers and cancellation
stale state information indicating that a thread was possibly blocked at a cancellation point could get left behind if longjmp was used to exit a signal handler that interrupted a cancellation point. to fix the issue, we throw away the state information entirely and simply compare the saved instruction pointer to a range of code addresses in the __syscall_cp_asm function. all the ugly PIC work (which becomes minimal anyway with this approach) is defered to cancellation time instead of happening at every syscall, which should improve performance too. this commit also fixes cancellation on arm, which was mildly broken (race condition, not checking cancellation flag once inside the cancellation point zone). apparently i forgot to implement that. the new arm code is untested, but appears correct; i'll test and fix it later if there are problems.
Diffstat (limited to 'src/thread/arm/syscall_cp.s')
1 files changed, 8 insertions, 10 deletions
diff --git a/src/thread/arm/syscall_cp.s b/src/thread/arm/syscall_cp.s
index 59924fc5..0cc23b1f 100644
--- a/src/thread/arm/syscall_cp.s
+++ b/src/thread/arm/syscall_cp.s
@@ -3,20 +3,18 @@
mov ip,sp
stmfd sp!,{r4,r5,r6,r7,lr}
- stmfd sp!,{r0}
- bl 1f
-1: mov r4,#(1f-.)
- add r4,r4,lr
- str r4,[r0,#4]
- str sp,[r0] __cp_begin
+ ld r0,[r0]
+ cmp r0,#0
+ blne __cancel
mov r7,r1
mov r0,r2
mov r1,r3
ldmfd ip,{r2,r3,r4,r5,r6}
-1: svc 0
- ldmfd sp!,{r1}
- mov r2,#0
- str r2,[r1]
+ svc 0 __cp_end
ldmfd sp!,{r4,r5,r6,r7,lr}
tst lr,#1
moveq pc,lr