@@ -1,3 +1,16 @@
+2016-04-15 Adhemerval Zanella <adhemerval.zanella@linaro.org>
+
+ * sysdeps/unix/sysv/linux/Makefile [$(subdir) == nptl] (test): Remove
+ tst-getpid2.
+ * sysdeps/unix/sysv/linux/aarch64/clone.S (__clone): Do not change
+ pid/tid fields for CLONE_VM.
+ * sysdeps/unix/sysv/linux/arm/clone.S: Likewise.
+ * sysdeps/unix/sysv/linux/i386/clone.S: Likewise.
+ * sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S: Likewise.
+ * sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S: Likewise.
+ * sysdeps/unix/sysv/linux/x86_64/clone.S: Likewise.
+ * sysdeps/unix/sysv/linux/tst-getpid2.c: Remove file.
+
2016-04-15 Mike Frysinger <vapier@gentoo.org>
* locale/iso-4217.def: Add SSP and change ZMK to ZMW.
@@ -194,7 +194,7 @@ CFLAGS-gai.c += -DNEED_NETLINK
endif
ifeq ($(subdir),nptl)
-tests += tst-setgetname tst-align-clone tst-getpid1 tst-getpid2 \
+tests += tst-setgetname tst-align-clone tst-getpid1 \
tst-thread-affinity-pthread tst-thread-affinity-pthread2 \
tst-thread-affinity-sched
endif
@@ -72,9 +72,11 @@ thread_start:
cfi_undefined (x30)
mov x29, 0
- tbnz x11, #CLONE_THREAD_BIT, 3f
- mov x0, #-1
- tbnz x11, #CLONE_VM_BIT, 2f
+ mov x0, CLONE_VM
+ movk x0, CLONE_THREAD>>16, lsl 16
+ tst x0, x11
+ bne 3f
+
mov x8, #SYS_ify(getpid)
svc 0x0
2:
@@ -72,13 +72,12 @@ PSEUDO_END (__clone)
.cantunwind
tst ip, #CLONE_THREAD
bne 3f
+ tst ip, #CLONE_VM
+ bne 3f
GET_TLS (lr)
mov r1, r0
- tst ip, #CLONE_VM
ldr r7, =SYS_ify(getpid)
- ite ne
- movne r0, #-1
- swieq 0x0
+ swi 0x0
NEGOFF_ADJ_BASE (r1, TID_OFFSET)
str r0, NEGOFF_OFF1 (r1, TID_OFFSET)
str r0, NEGOFF_OFF2 (r1, PID_OFFSET, TID_OFFSET)
@@ -108,7 +108,7 @@ L(thread_start):
cfi_undefined (eip);
/* Note: %esi is zero. */
movl %esi,%ebp /* terminate the stack frame */
- testl $CLONE_THREAD, %edi
+ testl $(CLONE_THREAD | CLONE_VM), %edi
je L(newpid)
L(haspid):
call *%ebx
@@ -124,9 +124,6 @@ L(here):
.subsection 2
L(newpid):
- testl $CLONE_VM, %edi
- movl $-1, %eax
- jne L(nomoregetpid)
movl $SYS_ify(getpid), %eax
ENTER_KERNEL
L(nomoregetpid):
@@ -76,11 +76,13 @@ ENTRY (__clone)
crandc cr1*4+eq,cr1*4+eq,cr0*4+so
bne- cr1,L(parent) /* The '-' is to minimise the race. */
- andis. r0,r28,CLONE_THREAD>>16
- bne+ r0,L(oldpid)
- andi. r0,r28,CLONE_VM
- li r3,-1
- bne- r0,L(nomoregetpid)
+ /* If CLONE_THREAD of CLONE_VM does not update the pid/tid field. */
+ lis r0,CLONE_THREAD>>16
+ ori r0,r0,CLONE_VM
+ and r0,r0,r29
+ cmpwi r0,0
+ bne+ cr0,L(oldpid)
+
DO_CALL(SYS_ify(getpid))
L(nomoregetpid):
stw r3,TID(r2)
@@ -78,11 +78,13 @@ ENTRY (__clone)
crandc cr1*4+eq,cr1*4+eq,cr0*4+so
bne- cr1,L(parent) /* The '-' is to minimise the race. */
- andis. r0,r29,CLONE_THREAD>>16
+ /* If CLONE_THREAD of CLONE_VM does not update the pid/tid field. */
+ lis r0,CLONE_THREAD>>16
+ ori r0,r0,CLONE_VM
+ and r0,r0,r29
+ cmpwi r0,0
bne+ cr0,L(oldpid)
- andi. r0,r29,CLONE_VM
- li r3,-1
- bne- cr0,L(nomoregetpid)
+
DO_CALL(SYS_ify(getpid))
L(nomoregetpid):
stw r3,TID(r13)
deleted file mode 100644
@@ -1,2 +0,0 @@
-#define TEST_CLONE_FLAGS CLONE_VM
-#include "tst-getpid1.c"
@@ -92,14 +92,11 @@ L(thread_start):
the outermost frame obviously. */
xorl %ebp, %ebp
- testq $CLONE_THREAD, %rdi
+ andq $(CLONE_THREAD | CLONE_VM), %rdi
jne 1f
- testq $CLONE_VM, %rdi
- movl $-1, %eax
- jne 2f
movl $SYS_ify(getpid), %eax
syscall
-2: movl %eax, %fs:PID
+ movl %eax, %fs:PID
movl %eax, %fs:TID
1:
As discussed in libc-alpha [1] current clone with CLONE_VM (without CLONE_THREAD set) will reset the pthread pid/tid fields to -1. The issue is since memory is shared between the parent and chield it will clobber parent's cached pid/tid leading to internal inconsistencies if the value is not restore. And even it is restore it may lead to racy condition when between set/restore a thread might invoke pthread function that validate the pthread with INVALID_TD_P/INVALID_NOT_TERMINATED_TD_P and thus get wrong results due inconsistent internal pthread state. As stated in BZ19957, previously reports of this behaviour was close with EWONTFIX due the fact usage of clone outside glibc is tricky since glibc requires consistent internal pthread, while using clone directly may not provide it. However since now posix_spawn uses clone(CLONE_VM) to fixes various issues related to previous vfork usage this issue requires fixing. The vfork implementation also does something similar, but instead it negates and restores only the *pid* field and functions that might access its value know to handle such case (getpid, raise and pthread ones that uses INVALID_TD_P/INVALID_NOT_TERMINATED_TD_P macros that check only *tid* field). Also vfork does not call __clone directly, instead calling either __NR_vfork or __NR_clone directly. So this patch removes this clone behavior by avoiding setting the pthread pid/tid field for CLONE_VM as well for CLONE_THREAD. Instead of current approach of: int clone(int (*fn)(void *), void *child_stack, int flags, ...) [...] if (flags & CLONE_THREAD) goto do_syscall; pid_t new_value; if (flags & CLONE_VM) new_value = -1; else new_value = getpid (); THREAD_SETMEM (THREAD_SELF, pid, new_value); THREAD_SETMEM (THREAD_SELF, tid, new_value); do_syscall: [...] The new approach uses: int clone(int (*fn)(void *), void *child_stack, int flags, ...) [...] if (flags & CLONE_THREAD || flags & CLONE_VM) goto do_syscall; pid_t new_value = getpid (); THREAD_SETMEM (THREAD_SELF, pid, new_value); THREAD_SETMEM (THREAD_SELF, tid, new_value); do_syscall: [...] It also removes the linux tst-getpid2.c test which expects the previous behavior. I only fixed the clone.S implementations for i386, x86_64, powerpc, aarch64, and arm (basically the ones I have a way to actually test it). If would like to ask for some help on fixing the remaning ones: sparc (32 and 64-bit), alpha, s390 (32 and 64-bit), microblaze, sh, ia64, tile, hppa, m68k, nio2, and mips. Tested on x86_64, i686, x32, powerpc64le, aarch64, and armhf. [1] https://sourceware.org/ml/libc-alpha/2016-04/msg00307.html --- ChangeLog | 13 +++++++++++++ sysdeps/unix/sysv/linux/Makefile | 2 +- sysdeps/unix/sysv/linux/aarch64/clone.S | 8 +++++--- sysdeps/unix/sysv/linux/arm/clone.S | 7 +++---- sysdeps/unix/sysv/linux/i386/clone.S | 5 +---- sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S | 12 +++++++----- sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S | 10 ++++++---- sysdeps/unix/sysv/linux/tst-getpid2.c | 2 -- sysdeps/unix/sysv/linux/x86_64/clone.S | 7 ++----- 9 files changed, 38 insertions(+), 28 deletions(-) delete mode 100644 sysdeps/unix/sysv/linux/tst-getpid2.c -- 1.9.1