runtime: linux signal masking

Fixes #3101 (Linux).

R=golang-dev, bradfitz, minux.ma
CC=golang-dev
https://golang.org/cl/5696043

diff --git a/src/pkg/runtime/os_linux.h b/src/pkg/runtime/os_linux.h
index 82498c9888d479b5f23e06e1bdc07294387edfac..ab948ddc1763093c8d3cf4143032698b253dc2d8 100644 (file)
--- a/src/pkg/runtime/os_linux.h
+++ b/src/pkg/runtime/os_linux.h
@@ -22,3 +22,14 @@ void runtime·raisesigpipe(void);
 
 #define        NSIG    65
 #define        SI_USER 0
+
+// It's hard to tease out exactly how big a Sigset is, but
+// rt_sigprocmask crashes if we get it wrong, so if binaries
+// are running, this is right.
+typedef struct Sigset Sigset;
+struct Sigset
+{
+       uint32 mask[2];
+};
+void   runtime·rtsigprocmask(int32, Sigset*, Sigset*, int32);
+#define SIG_SETMASK 2

diff --git a/src/pkg/runtime/sys_linux_386.s b/src/pkg/runtime/sys_linux_386.s
index bee785407f5fd8e9b483af095a495543446a0d89..32a18ed03dd7f6a8c93b75ddfbf07ff483596838 100644 (file)
--- a/src/pkg/runtime/sys_linux_386.s
+++ b/src/pkg/runtime/sys_linux_386.s
@@ -136,6 +136,18 @@ TEXT runtime·nanotime(SB), 7, $32
        MOVL    DX, 4(DI)
        RET
 
+TEXT runtime·rtsigprocmask(SB),7,$0
+       MOVL    $175, AX                // syscall entry
+       MOVL    4(SP), BX
+       MOVL    8(SP), CX
+       MOVL    12(SP), DX
+       MOVL    16(SP), SI
+       CALL    *runtime·_vdso(SB)
+       CMPL    AX, $0xfffff001
+       JLS     2(PC)
+       INT $3
+       RET
+
 TEXT runtime·rt_sigaction(SB),7,$0
        MOVL    $174, AX                // syscall - rt_sigaction
        MOVL    4(SP), BX

diff --git a/src/pkg/runtime/sys_linux_amd64.s b/src/pkg/runtime/sys_linux_amd64.s
index 68c2bf0eb70cc4c901770324b5e3d9cab0b93406..84972b4533413e5dae8f9b75dd10957e00fa7b88 100644 (file)
--- a/src/pkg/runtime/sys_linux_amd64.s
+++ b/src/pkg/runtime/sys_linux_amd64.s
@@ -123,6 +123,18 @@ TEXT runtime·nanotime(SB), 7, $32
        ADDQ    DX, AX
        RET
 
+TEXT runtime·rtsigprocmask(SB),7,$0-32
+       MOVL    8(SP), DI
+       MOVQ    16(SP), SI
+       MOVQ    24(SP), DX
+       MOVL    32(SP), R10
+       MOVL    $14, AX                 // syscall entry
+       SYSCALL
+       CMPQ    AX, $0xfffffffffffff001
+       JLS     2(PC)
+       CALL    runtime·notok(SB)
+       RET
+
 TEXT runtime·rt_sigaction(SB),7,$0-32
        MOVL    8(SP), DI
        MOVQ    16(SP), SI

diff --git a/src/pkg/runtime/sys_linux_arm.s b/src/pkg/runtime/sys_linux_arm.s
index 8f30bff94bac8f18ba0326838e6b1b819332714d..fed963f0dc311014535e9b6621efe6c29887e581 100644 (file)
--- a/src/pkg/runtime/sys_linux_arm.s
+++ b/src/pkg/runtime/sys_linux_arm.s
@@ -23,6 +23,7 @@
 #define SYS_clone (SYS_BASE + 120)
 #define SYS_rt_sigreturn (SYS_BASE + 173)
 #define SYS_rt_sigaction (SYS_BASE + 174)
+#define SYS_rt_sigprocmask (SYS_BASE + 175)
 #define SYS_sigaltstack (SYS_BASE + 186)
 #define SYS_mmap2 (SYS_BASE + 192)
 #define SYS_futex (SYS_BASE + 240)
@@ -292,6 +293,15 @@ TEXT runtime·sigtramp(SB),7,$24
 
        RET
 
+TEXT runtime·rtsigprocmask(SB),7,$0
+       MOVW    0(FP), R0
+       MOVW    4(FP), R1
+       MOVW    8(FP), R2
+       MOVW    12(FP), R3
+       MOVW    $SYS_rt_sigprocmask, R7
+       SWI     $0
+       RET
+
 TEXT runtime·rt_sigaction(SB),7,$0
        MOVW    0(FP), R0
        MOVW    4(FP), R1

diff --git a/src/pkg/runtime/thread_linux.c b/src/pkg/runtime/thread_linux.c
index d18574145bd6dd001fd440373ff2bc605ec61d64..005fb1df6a4340e038452ddbdb2a021db91f8511 100644 (file)
--- a/src/pkg/runtime/thread_linux.c
+++ b/src/pkg/runtime/thread_linux.c
@@ -13,6 +13,9 @@ int32 runtime·open(uint8*, int32, int32);
 int32 runtime·close(int32);
 int32 runtime·read(int32, void*, int32);
 
+static Sigset sigset_all = { ~(uint32)0, ~(uint32)0 };
+static Sigset sigset_none;
+
 // Linux futex.
 //
 //     futexsleep(uint32 *addr, uint32 val)
@@ -135,6 +138,7 @@ runtime·newosproc(M *m, G *g, void *stk, void (*fn)(void))
 {
        int32 ret;
        int32 flags;
+       Sigset oset;
 
        /*
         * note: strace gets confused if we use CLONE_PTRACE here.
@@ -152,7 +156,13 @@ runtime·newosproc(M *m, G *g, void *stk, void (*fn)(void))
                        stk, m, g, fn, runtime·clone, m->id, m->tls[0], &m);
        }
 
-       if((ret = runtime·clone(flags, stk, m, g, fn)) < 0) {
+       // Disable signals during clone, so that the new thread starts
+       // with signals disabled.  It will enable them in minit.
+       runtime·rtsigprocmask(SIG_SETMASK, &sigset_all, &oset, sizeof oset);
+       ret = runtime·clone(flags, stk, m, g, fn);
+       runtime·rtsigprocmask(SIG_SETMASK, &oset, nil, sizeof oset);
+
+       if(ret < 0) {
                runtime·printf("runtime: failed to create new OS thread (have %d already; errno=%d)\n", runtime·mcount(), -ret);
                runtime·throw("runtime.newosproc");
        }
@@ -177,6 +187,7 @@ runtime·minit(void)
        // Initialize signal handling.
        m->gsignal = runtime·malg(32*1024);    // OS X wants >=8K, Linux >=2K
        runtime·signalstack(m->gsignal->stackguard - StackGuard, 32*1024);
+       runtime·rtsigprocmask(SIG_SETMASK, &sigset_none, nil, sizeof sigset_none);
 }
 
 void