code review 10271047: cmd/5l,runtime: External linking support on linux-arm

src/pkg/runtime/rt0_linux_arm.s

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-TEXT _rt0_arm_linux(SB),7,$-4
+#include "../../cmd/ld/textflag.h"
+
+TEXT _rt0_arm_linux(SB),NOSPLIT,$-4
         MOVW    (R13), R0       // argc
         MOVW    $4(R13), R1             // argv
-        MOVM.DB.W [R0-R1], (R13)
         MOVW    $_rt0_arm_linux1(SB), R4
         B               (R4)
 
-TEXT _rt0_arm_linux1(SB),7,$-4
+TEXT _rt0_arm_linux1(SB),NOSPLIT,$-4
         // We first need to detect the kernel ABI, and warn the user
         // if the system only supports OABI
         // The strategy here is to call some EABI syscall to see if
         // SIGILL is received.
         // To catch SIGILL, we have to first setup sigaction, this is
         // a chicken-and-egg problem, because we can't do syscall if
         // we don't know the kernel ABI... Oh, not really, we can do
         // syscall in Thumb mode.
 
+        // Save argc and argv
+        MOVM.DB.W [R0-R1], (R13)
         // set up sa_handler
         MOVW    $bad_abi<>(SB), R0 // sa_handler
         MOVW    $0, R1 // sa_flags
         MOVW    $0, R2 // sa_restorer
         MOVW    $0, R3 // sa_mask
         MOVM.DB.W [R0-R3], (R13)
         MOVW    $4, R0 // SIGILL
         MOVW    R13, R1 // sa
         SUB     $16, R13
         MOVW    R13, R2 // old_sa
@@ skipping 11 matching lines @@
         MOVW    $8, R3 // c
         MOVW    $174, R7 // sys_sigaction
         SWI     $0 // restore signal handler
         ADD     $32, R13
 
         SUB     $4, R13 // fake a stack frame for runtime·setup_auxv
         BL      runtime·setup_auxv(SB)
         ADD     $4, R13
         B       _rt0_go(SB)
 
-TEXT bad_abi<>(SB),7,$-4
+TEXT bad_abi<>(SB),NOSPLIT,$-4
         // give diagnosis and exit
         MOVW    $2, R0 // stderr
         MOVW    $bad_abi_msg(SB), R1 // data
         MOVW    $45, R2 // len
         MOVW    $4, R7 // sys_write
         BL      oabi_syscall<>(SB)
         MOVW    $1, R0
         MOVW    $1, R7 // sys_exit
         BL      oabi_syscall<>(SB)
         B       0(PC)
 
 DATA bad_abi_msg+0x00(SB)/8, $"This pro"
 DATA bad_abi_msg+0x08(SB)/8, $"gram can"
 DATA bad_abi_msg+0x10(SB)/8, $" only be"
 DATA bad_abi_msg+0x18(SB)/8, $" run on "
 DATA bad_abi_msg+0x20(SB)/8, $"EABI ker"
 DATA bad_abi_msg+0x28(SB)/4, $"nels"
 DATA bad_abi_msg+0x2c(SB)/1, $0xa
 GLOBL bad_abi_msg(SB), $45
 
-TEXT oabi_syscall<>(SB),7,$-4
+TEXT oabi_syscall<>(SB),NOSPLIT,$-4
         ADD $1, PC, R4
         WORD $0xe12fff14 //BX   (R4) // enter thumb mode
         // TODO(minux): only supports little-endian CPUs
         WORD $0x4770df01 // swi $1; bx lr
 
-TEXT main(SB),7,$-8
-        MOVM.DB.W       [R0-R1], (R13) // argc, argv
+TEXT main(SB),NOSPLIT,$-8

[rsc, 2013/08/13 19:05:49]

$-8 doesnt mean what you think it means. should be $-4.

         MOVW    $_rt0_arm_linux1(SB), R4
         B               (R4)
+