# This patch changes all cases where the ARM assembler mov pc,rx # instructions are used to ensure that the thumb/arm interwork change of # process more works - in essence mov pc,rx needs to become bx rc. # # The ldr pc or ldm rx, {pc} instructions are not changed - this is # fine on ARM >=v5 but will fail to restore thumb mode on ARM v4T, # i.e. this code will not provide support for thumb on ARM v4T. # # One mov pc is left in resolve.S, this is fixed in a different patch - # thumb-resolve.patch # # The changes are protected by __THUMB_INTERWORK__ - the original # mov instruction will work on newer architectures and is required on # arch v4 (not v4t) and earlier - those which did not support thumb - # so this is safe. See gcc lib1asmfuncs for a more exact test. # --- uClibc-0.9.28/.pc/thumb-mov-pc-bx.patch/ldso/ldso/arm/dl-startup.h 2005-08-17 15:49:41.000000000 -0700 +++ uClibc-0.9.28/ldso/ldso/arm/dl-startup.h 2005-09-16 23:38:34.266546180 -0700 @@ -4,6 +4,7 @@ * Copyright (C) 2000-2004 by Erik Andersen <andersen@codepoet.org> */ +#if defined(__arm__) asm( " .text\n" " .globl _start\n" @@ -40,7 +41,11 @@ " ldr r0, .L_FINI_PROC\n" " ldr r0, [sl, r0]\n" " @ jump to the user_s entry point\n" +#if defined(__THUMB_INTERWORK__) + " bx r6\n" +#else " mov pc, r6\n" +#endif ".L_GET_GOT:\n" " .word _GLOBAL_OFFSET_TABLE_ - .L_GOT_GOT - 4\n" ".L_SKIP_ARGS:\n" @@ -51,6 +56,70 @@ " .size _start,.-_start\n" ".previous\n" ); +#else +asm( + " .text\n" + " .arm\n" + " .globl _start\n" + " .type _start,%function\n" + "_start:\n" + " @ dumb: can't persuade the linker to make the start address\n" + " @ odd, so use an arm function and change to thumb (_dl_start\n" + " @ is thumb)\n" + " adr r0, __dl_thumb_start+1\n" + " bx r0\n" + "\n\n" + " .thumb\n" + " .globl __dl_thumb_start\n" + " .thumb_func\n" + " .type __dl_thumb_start,%function\n" + "__dl_thumb_start:\n" + " @ at start time, all the args are on the stack\n" + " mov r0, sp\n" + " bl _dl_start\n" + " @ returns user entry point in r0\n" + " mov r6, r0\n" + " @ we are PIC code, so get global offset table\n" + " ldr r7, .L_GET_GOT\n" + ".L_GOT_GOT:\n" + " add r7, pc\n" + " @ See if we were run as a command with the executable file\n" + " @ name as an extra leading argument.\n" + " ldr r4, .L_SKIP_ARGS\n" + " ldr r4, [r7, r4]\n" + " @ get the original arg count\n" + " ldr r1, [sp]\n" + " @ subtract _dl_skip_args from it\n" + " sub r1, r1, r4\n" + " @ adjust the stack pointer to skip them\n" + " lsl r4, r4, #2\n" + " add sp, r4\n" + " @ get the argv address\n" + " add r2, sp, #4\n" + " @ store the new argc in the new stack location\n" + " str r1, [sp]\n" + " @ compute envp\n" + " lsl r3, r1, #2\n" + " add r3, r3, r2\n" + " add r3, #4\n" + "\n\n" + " @ load the finalizer function\n" + " ldr r0, .L_FINI_PROC\n" + " ldr r0, [r7, r0]\n" + " @ jump to the user_s entry point\n" + " bx r6\n" + "\n\n" + ".L_GET_GOT:\n" + " .word _GLOBAL_OFFSET_TABLE_ - .L_GOT_GOT - 4\n" + ".L_SKIP_ARGS:\n" + " .word _dl_skip_args(GOTOFF)\n" + ".L_FINI_PROC:\n" + " .word _dl_fini(GOT)\n" + "\n\n" + " .size _start,.-_start\n" + ".previous\n" +); +#endif /* Get a pointer to the argv array. On many platforms this can be just --- uClibc-0.9.28/.pc/thumb-mov-pc-bx.patch/ldso/ldso/arm/dl-sysdep.h 2005-08-17 15:49:41.000000000 -0700 +++ uClibc-0.9.28/ldso/ldso/arm/dl-sysdep.h 2005-09-07 20:10:35.923583424 -0700 @@ -85,7 +85,19 @@ extern void __dl_start asm ("_dl_start"); Elf32_Addr got_addr = (Elf32_Addr) &__dl_start; Elf32_Addr pcrel_addr; +#if !defined(__thumb__) + /* On thumb this has to be two instructions because + * the offset is negative. + */ asm ("adr %0, _dl_start" : "=r" (pcrel_addr)); +#else + /* This is dumb, gcc should support a thumb adrl + * but it doesn't, so this is the same thing the + * hard way. If this code moves too far from _dl_start + * it will fail. + */ + asm ("adr\t%0, 1f\n1:\tsub\t%0, #1b-_dl_start\n" : "=r" (pcrel_addr)); +#endif return pcrel_addr - got_addr; } --- uClibc-0.9.28/.pc/thumb-mov-pc-bx.patch/libc/sysdeps/linux/arm/clone.S 2005-08-17 15:49:41.000000000 -0700 +++ uClibc-0.9.28/libc/sysdeps/linux/arm/clone.S 2005-09-08 09:36:24.801986529 -0700 @@ -51,7 +51,11 @@ swi __NR_clone movs a1, a1 blt __error - movne pc, lr +#if defined(__THUMB_INTERWORK__) + bxne lr +#else + movne pc, lr +#endif @ pick the function arg and call address off the stack and execute ldr r0, [sp, #4] --- uClibc-0.9.28/.pc/thumb-mov-pc-bx.patch/libc/sysdeps/linux/arm/vfork.S 2005-08-17 15:49:41.000000000 -0700 +++ uClibc-0.9.28/libc/sysdeps/linux/arm/vfork.S 2005-09-08 09:51:13.377901086 -0700 @@ -34,7 +34,11 @@ #ifdef __NR_vfork swi __NR_vfork cmn r0, #4096 +#if defined(__THUMB_INTERWORK__) + bxcc lr +#else movcc pc, lr +#endif /* Check if vfork even exists. */ ldr r1, =-ENOSYS @@ -47,7 +51,11 @@ cmn r0, #4096 /* Syscal worked. Return to child/parent */ - movcc pc, lr +#if defined(__THUMB_INTERWORK__) + bxcc lr +#else + movcc pc, lr +#endif __error: b __syscall_error