From 75bce1a7320f94c36854fc958fa93937ed92bf83 Mon Sep 17 00:00:00 2001 From: Christophe Lyon Date: Wed, 4 Jul 2018 17:55:19 +0200 Subject: rtld: Add startup code MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Implement _start: compute parameters for __self_reloc, and give control to the user program. * ldso/ldso/arm/dl-startup.h: Implement _start for __FDPIC__. Signed-off-by: Mickaël Guêné Signed-off-by: Christophe Lyon --- ldso/ldso/arm/dl-startup.h | 67 +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 66 insertions(+), 1 deletion(-) diff --git a/ldso/ldso/arm/dl-startup.h b/ldso/ldso/arm/dl-startup.h index ea1e9f6f9..06c95cb44 100644 --- a/ldso/ldso/arm/dl-startup.h +++ b/ldso/ldso/arm/dl-startup.h @@ -8,6 +8,71 @@ #include #include +#if defined(__FDPIC__) +#if !defined(__thumb__) || defined(__thumb2__) +__asm__( + " .arm\n" + " .text\n" + " .globl _start\n" + " .type _start,%function\n" + "_start:\n" + /* We compute the parameters for __self_reloc: + - r0 is a pointer to the loadmap (either from r8 or r7 if rtld is + lauched in standalone mode) + - r1 is a pointer to the start of .rofixup section + - r2 is a pointer to the last word of .rofixup section + + __self_reloc will fix indirect addresses in .rofixup + section and will return the relocated GOT value. + */ + " sub r4, pc, #8\n" + " ldr r1, .L__ROFIXUP_LIST__\n" + " add r1, r1, r4\n" + " ldr r2, .L__ROFIXUP_END__\n" + " add r2, r2, r4\n" + " movs r0, r8\n" + " moveq r0, r7\n" + " push {r7, r8, r9, r10}\n" + " bl __self_reloc;\n" + " pop {r7, r8, r9, r10}\n" + /* We compute the parameters for dl_start(). See DL_START() + macro below. The address of the user entry point is + returned in dl_main_funcdesc (on stack). */ + " mov r1, r7\n" + " mov r2, r8\n" + " mov r3, r9\n" + " mov r4, sp\n" + " sub r5, sp, #8\n" + " sub sp, sp, #16\n" + " str r4, [sp, #4]\n" + " str r5, [sp, #0]\n" + " mov r9, r0\n" + /* Save r9 into r4, to preserve the GOT pointer. */ + " mov r4, r9\n" + " bl _dl_start;\n" + /* Now compute parameters for entry point according to FDPIC ABI. */ + " ldr r10, .L_dl_fini_gotofffuncdesc\n" + /* Save GOT value from r4. */ + " add r10, r10, r4\n" + " ldr r5, [sp, #8]\n" + " ldr r9, [sp, #12]\n" + " add sp, sp, #16\n" + " bx r5\n" + ".loopforever:\n" + " b .loopforever\n" + ".L__ROFIXUP_LIST__:\n" + " .word __ROFIXUP_LIST__ - _start\n" + ".L__ROFIXUP_END__:\n" + " .word __ROFIXUP_END__ - _start\n" + ".L_dl_fini_gotofffuncdesc:\n" + " .word _dl_fini(GOTOFFFUNCDESC)\n" + " .size _start,.-_start\n" + " .previous\n" +); +#else /* !defined(__thumb__) */ +#error Thumb-1 is not supported +#endif /* !defined(__thumb__) */ +#else /* defined(__FDPIC__) */ #if !defined(__thumb__) __asm__( " .text\n" @@ -121,7 +186,7 @@ __asm__( ".previous\n" ); #endif - +#endif /* defined(__FDPIC__) */ /* Get a pointer to the argv array. On many platforms this can be just * the address of the first argument, on other platforms we need to -- cgit v1.2.3