runtime, syscall: use int $0x80 to invoke syscalls on android/386

golang.org/cl/16796 broke android/386 by assuming behaviour specific to glibc's
dynamic linker. Copy bionic by using int $0x80 to invoke syscalls on
android/386 as the old alternative (CALL *runtime_vdso(SB)) cannot be compiled
without text relocations, which we want to get rid of on android.

Also remove "CALL *runtime_vdso(SB)" variant from the syscall package.

Change-Id: I6c01849f8dcbd073d000ddc8f13948a836b8b261
Reviewed-on: https://go-review.googlesource.com/16996
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

diff --git a/src/runtime/sys_linux_386.s b/src/runtime/sys_linux_386.s
index 98626d14c854bba57aab2d350930ffd5d46c0777..3067c03d0e1c952e08ef076a7f83ce93b0cc1ddd 100644 (file)
--- a/src/runtime/sys_linux_386.s
+++ b/src/runtime/sys_linux_386.s
@@ -10,17 +10,30 @@
 #include "go_tls.h"
 #include "textflag.h"
 
+// Most linux systems use glibc's dynamic linker, which puts the
+// __kernel_vsyscall vdso helper at 0x10(GS) for easy access from position
+// independent code and setldt in this file does the same in the statically
+// linked case. Android, however, uses bionic's dynamic linker, which does not
+// save the helper anywhere, and so the only way to invoke a syscall from
+// position independent code is boring old int $0x80 (which is also what
+// bionic's syscall wrappers use).
+#ifdef GOOS_android
+#define INVOKE_SYSCALL INT     $0x80
+#else
+#define INVOKE_SYSCALL CALL    0x10(GS)
+#endif
+
 TEXT runtime·exit(SB),NOSPLIT,$0
        MOVL    $252, AX        // syscall number
        MOVL    code+0(FP), BX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        INT $3  // not reached
        RET
 
 TEXT runtime·exit1(SB),NOSPLIT,$0
        MOVL    $1, AX  // exit - exit the current os thread
        MOVL    code+0(FP), BX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        INT $3  // not reached
        RET
 
@@ -29,7 +42,7 @@ TEXT runtime·open(SB),NOSPLIT,$0
        MOVL    name+0(FP), BX
        MOVL    mode+4(FP), CX
        MOVL    perm+8(FP), DX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     2(PC)
        MOVL    $-1, AX
@@ -39,7 +52,7 @@ TEXT runtime·open(SB),NOSPLIT,$0
 TEXT runtime·closefd(SB),NOSPLIT,$0
        MOVL    $6, AX          // syscall - close
        MOVL    fd+0(FP), BX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     2(PC)
        MOVL    $-1, AX
@@ -51,7 +64,7 @@ TEXT runtime·write(SB),NOSPLIT,$0
        MOVL    fd+0(FP), BX
        MOVL    p+4(FP), CX
        MOVL    n+8(FP), DX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     2(PC)
        MOVL    $-1, AX
@@ -63,7 +76,7 @@ TEXT runtime·read(SB),NOSPLIT,$0
        MOVL    fd+0(FP), BX
        MOVL    p+4(FP), CX
        MOVL    n+8(FP), DX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     2(PC)
        MOVL    $-1, AX
@@ -74,7 +87,7 @@ TEXT runtime·getrlimit(SB),NOSPLIT,$0
        MOVL    $191, AX                // syscall - ugetrlimit
        MOVL    kind+0(FP), BX
        MOVL    limit+4(FP), CX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, ret+8(FP)
        RET
 
@@ -93,31 +106,31 @@ TEXT runtime·usleep(SB),NOSPLIT,$8
        MOVL    $0, DX
        MOVL    $0, SI
        LEAL    0(SP), DI
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        RET
 
 TEXT runtime·gettid(SB),NOSPLIT,$0-4
        MOVL    $224, AX        // syscall - gettid
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, ret+0(FP)
        RET
 
 TEXT runtime·raise(SB),NOSPLIT,$12
        MOVL    $224, AX        // syscall - gettid
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, BX  // arg 1 tid
        MOVL    sig+0(FP), CX   // arg 2 signal
        MOVL    $238, AX        // syscall - tkill
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        RET
 
 TEXT runtime·raiseproc(SB),NOSPLIT,$12
        MOVL    $20, AX // syscall - getpid
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, BX  // arg 1 pid
        MOVL    sig+0(FP), CX   // arg 2 signal
        MOVL    $37, AX // syscall - kill
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        RET
 
 TEXT runtime·setitimer(SB),NOSPLIT,$0-12
@@ -125,7 +138,7 @@ TEXT runtime·setitimer(SB),NOSPLIT,$0-12
        MOVL    mode+0(FP), BX
        MOVL    new+4(FP), CX
        MOVL    old+8(FP), DX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        RET
 
 TEXT runtime·mincore(SB),NOSPLIT,$0-16
@@ -133,7 +146,7 @@ TEXT runtime·mincore(SB),NOSPLIT,$0-16
        MOVL    addr+0(FP), BX
        MOVL    n+4(FP), CX
        MOVL    dst+8(FP), DX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, ret+12(FP)
        RET
 
@@ -143,7 +156,7 @@ TEXT time·now(SB), NOSPLIT, $32
        MOVL    $0, BX          // CLOCK_REALTIME
        LEAL    8(SP), CX
        MOVL    $0, DX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    8(SP), AX       // sec
        MOVL    12(SP), BX      // nsec
 
@@ -160,7 +173,7 @@ TEXT runtime·nanotime(SB), NOSPLIT, $32
        MOVL    $1, BX          // CLOCK_MONOTONIC
        LEAL    8(SP), CX
        MOVL    $0, DX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    8(SP), AX       // sec
        MOVL    12(SP), BX      // nsec
 
@@ -181,7 +194,7 @@ TEXT runtime·rtsigprocmask(SB),NOSPLIT,$0
        MOVL    new+4(FP), CX
        MOVL    old+8(FP), DX
        MOVL    size+12(FP), SI
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     2(PC)
        INT $3
@@ -193,7 +206,7 @@ TEXT runtime·rt_sigaction(SB),NOSPLIT,$0
        MOVL    new+4(FP), CX
        MOVL    old+8(FP), DX
        MOVL    size+12(FP), SI
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, ret+16(FP)
        RET
 
@@ -235,7 +248,7 @@ TEXT runtime·mmap(SB),NOSPLIT,$0
        MOVL    fd+16(FP), DI
        MOVL    off+20(FP), BP
        SHRL    $12, BP
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     3(PC)
        NOTL    AX
@@ -247,7 +260,7 @@ TEXT runtime·munmap(SB),NOSPLIT,$0
        MOVL    $91, AX // munmap
        MOVL    addr+0(FP), BX
        MOVL    n+4(FP), CX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     2(PC)
        INT $3
@@ -258,7 +271,7 @@ TEXT runtime·madvise(SB),NOSPLIT,$0
        MOVL    addr+0(FP), BX
        MOVL    n+4(FP), CX
        MOVL    flags+8(FP), DX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        // ignore failure - maybe pages are locked
        RET
 
@@ -272,7 +285,7 @@ TEXT runtime·futex(SB),NOSPLIT,$0
        MOVL    ts+12(FP), SI
        MOVL    addr2+16(FP), DI
        MOVL    val3+20(FP), BP
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, ret+24(FP)
        RET
 
@@ -313,7 +326,7 @@ TEXT runtime·clone(SB),NOSPLIT,$0
 
        // Initialize AX to Linux tid
        MOVL    $224, AX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
 
        MOVL    0(SP), BX           // m
        MOVL    4(SP), DX           // g
@@ -364,7 +377,7 @@ TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
        MOVL    $186, AX        // sigaltstack
        MOVL    new+4(SP), BX
        MOVL    old+8(SP), CX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     2(PC)
        INT     $3
@@ -421,13 +434,13 @@ TEXT runtime·setldt(SB),NOSPLIT,$32
         */
        ADDL    $0x4, CX        // address
        MOVL    CX, 0(CX)
-#endif
-        // We copy the dynamic linker behaviour of storing the vsyscall entry point
-        // at 0x10(GS) so that it can be invoked by "CALL 0x10(GS)" in all
-        // situations, not only those where the binary is actually dynamically
-        // linked.
+        // We copy the glibc dynamic linker behaviour of storing the
+        // __kernel_vsyscall entry point at 0x10(GS) so that it can be invoked
+        // by "CALL 0x10(GS)" in all situations, not only those where the
+        // binary is actually dynamically linked.
        MOVL    runtime·_vdso(SB), AX
        MOVL    AX, 0x10(CX)
+#endif
 
        // set up user_desc
        LEAL    16(SP), AX      // struct user_desc
@@ -459,7 +472,7 @@ TEXT runtime·setldt(SB),NOSPLIT,$32
 
 TEXT runtime·osyield(SB),NOSPLIT,$0
        MOVL    $158, AX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        RET
 
 TEXT runtime·sched_getaffinity(SB),NOSPLIT,$0
@@ -467,7 +480,7 @@ TEXT runtime·sched_getaffinity(SB),NOSPLIT,$0
        MOVL    pid+0(FP), BX
        MOVL    len+4(FP), CX
        MOVL    buf+8(FP), DX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, ret+12(FP)
        RET
 
@@ -475,7 +488,7 @@ TEXT runtime·sched_getaffinity(SB),NOSPLIT,$0
 TEXT runtime·epollcreate(SB),NOSPLIT,$0
        MOVL    $254, AX
        MOVL    size+0(FP), BX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, ret+4(FP)
        RET
 
@@ -483,7 +496,7 @@ TEXT runtime·epollcreate(SB),NOSPLIT,$0
 TEXT runtime·epollcreate1(SB),NOSPLIT,$0
        MOVL    $329, AX
        MOVL    flags+0(FP), BX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, ret+4(FP)
        RET
 
@@ -494,7 +507,7 @@ TEXT runtime·epollctl(SB),NOSPLIT,$0
        MOVL    op+4(FP), CX
        MOVL    fd+8(FP), DX
        MOVL    ev+12(FP), SI
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, ret+16(FP)
        RET
 
@@ -505,7 +518,7 @@ TEXT runtime·epollwait(SB),NOSPLIT,$0
        MOVL    ev+4(FP), CX
        MOVL    nev+8(FP), DX
        MOVL    timeout+12(FP), SI
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, ret+16(FP)
        RET
 
@@ -515,7 +528,7 @@ TEXT runtime·closeonexec(SB),NOSPLIT,$0
        MOVL    fd+0(FP), BX  // fd
        MOVL    $2, CX  // F_SETFD
        MOVL    $1, DX  // FD_CLOEXEC
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        RET
 
 // int access(const char *name, int mode)
@@ -523,7 +536,7 @@ TEXT runtime·access(SB),NOSPLIT,$0
        MOVL    $33, AX  // syscall - access
        MOVL    name+0(FP), BX
        MOVL    mode+4(FP), CX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, ret+8(FP)
        RET
 
@@ -534,7 +547,7 @@ TEXT runtime·connect(SB),NOSPLIT,$0-16
        MOVL    $102, AX  // syscall - socketcall
        MOVL    $3, BX  // connect
        LEAL    fd+0(FP), CX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, ret+12(FP)
        RET
 
@@ -545,6 +558,6 @@ TEXT runtime·socket(SB),NOSPLIT,$0-16
        MOVL    $102, AX  // syscall - socketcall
        MOVL    $1, BX  // socket
        LEAL    domain+0(FP), CX
-       CALL    0x10(GS)
+       INVOKE_SYSCALL
        MOVL    AX, ret+12(FP)
        RET

diff --git a/src/syscall/asm_linux_386.s b/src/syscall/asm_linux_386.s
index ec7487b4b9a4f1075c59a04453822c1b44b72a76..c94060571b11c0205b5e22f1580f4c6cd09c1b9a 100644 (file)
--- a/src/syscall/asm_linux_386.s
+++ b/src/syscall/asm_linux_386.s
@@ -12,6 +12,19 @@
 // func Syscall(trap uintptr, a1, a2, a3 uintptr) (r1, r2, err uintptr);
 // Trap # in AX, args in BX CX DX SI DI, return in AX
 
+// Most linux systems use glibc's dynamic linker, which puts the
+// __kernel_vsyscall vdso helper at 0x10(GS) for easy access from position
+// independent code and setldt in runtime does the same in the statically
+// linked case. Android, however, uses bionic's dynamic linker, which does not
+// save the helper anywhere, and so the only way to invoke a syscall from
+// position independent code is boring old int $0x80 (which is also what
+// bionic's syscall wrappers use).
+#ifdef GOOS_android
+#define INVOKE_SYSCALL INT     $0x80
+#else
+#define INVOKE_SYSCALL CALL    0x10(GS)
+#endif
+
 TEXT   ·Syscall(SB),NOSPLIT,$0-28
        CALL    runtime·entersyscall(SB)
        MOVL    trap+0(FP), AX  // syscall entry
@@ -20,7 +33,7 @@ TEXT  ·Syscall(SB),NOSPLIT,$0-28
        MOVL    a3+12(FP), DX
        MOVL    $0, SI
        MOVL    $0,  DI
-       CALL    *runtime·_vdso(SB)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     ok
        MOVL    $-1, r1+16(FP)
@@ -46,7 +59,7 @@ TEXT  ·Syscall6(SB),NOSPLIT,$0-40
        MOVL    a4+16(FP), SI
        MOVL    a5+20(FP), DI
        MOVL    a6+24(FP), BP
-       CALL    *runtime·_vdso(SB)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     ok6
        MOVL    $-1, r1+28(FP)
@@ -70,7 +83,7 @@ TEXT ·RawSyscall(SB),NOSPLIT,$0-28
        MOVL    a3+12(FP), DX
        MOVL    $0, SI
        MOVL    $0,  DI
-       CALL    *runtime·_vdso(SB)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     ok1
        MOVL    $-1, r1+16(FP)
@@ -93,7 +106,7 @@ TEXT ·RawSyscall6(SB),NOSPLIT,$0-40
        MOVL    a4+16(FP), SI
        MOVL    a5+20(FP), DI
        MOVL    a6+24(FP), BP
-       CALL    *runtime·_vdso(SB)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     ok2
        MOVL    $-1, r1+28(FP)
@@ -119,7 +132,7 @@ TEXT ·socketcall(SB),NOSPLIT,$0-36
        MOVL    $0, DX
        MOVL    $0, SI
        MOVL    $0,  DI
-       CALL    *runtime·_vdso(SB)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     oksock
        MOVL    $-1, n+28(FP)
@@ -142,7 +155,7 @@ TEXT ·rawsocketcall(SB),NOSPLIT,$0-36
        MOVL    $0, DX
        MOVL    $0, SI
        MOVL    $0,  DI
-       CALL    *runtime·_vdso(SB)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     oksock1
        MOVL    $-1, n+28(FP)
@@ -168,7 +181,7 @@ TEXT ·seek(SB),NOSPLIT,$0-28
        MOVL    offset_lo+4(FP), DX
        LEAL    newoffset_lo+16(FP), SI // result pointer
        MOVL    whence+12(FP),  DI
-       CALL    *runtime·_vdso(SB)
+       INVOKE_SYSCALL
        CMPL    AX, $0xfffff001
        JLS     okseek
        MOVL    $-1, newoffset_lo+16(FP)