From b30bd74dbcc48aca94b10531bb3056c5ef401752 Mon Sep 17 00:00:00 2001 From: Waldemar Brodkorb Date: Sat, 25 Mar 2017 18:12:28 +0100 Subject: nios2: allow to hack on experimenting ld.so support --- extra/Configs/Config.nios2 | 1 - ldso/ldso/dl-startup.c | 12 ++++++ ldso/ldso/nios2/dl-startup.h | 96 +++++++++++++++++++++++++++++++++++++++----- 3 files changed, 98 insertions(+), 11 deletions(-) diff --git a/extra/Configs/Config.nios2 b/extra/Configs/Config.nios2 index 958607cb3..8fcb01be7 100644 --- a/extra/Configs/Config.nios2 +++ b/extra/Configs/Config.nios2 @@ -11,4 +11,3 @@ config FORCE_OPTIONS_FOR_ARCH bool default y select ARCH_LITTLE_ENDIAN - select ARCH_HAS_NO_LDSO diff --git a/ldso/ldso/dl-startup.c b/ldso/ldso/dl-startup.c index 87f564f48..218b20f53 100644 --- a/ldso/ldso/dl-startup.c +++ b/ldso/ldso/dl-startup.c @@ -99,6 +99,10 @@ extern ElfW(Addr) _begin[] attribute_hidden; #endif +#ifdef LDSO_NEED_DPNT +ElfW(Dyn) *_dl_saved_dpnt = 0; +#endif + /* Static declarations */ static int (*_dl_elf_main) (int, char **, char **); @@ -341,6 +345,14 @@ DL_START(unsigned long args) fixed up by now. Still no function calls outside of this library, since the dynamic resolver is not yet ready. */ +#ifdef LDSO_NEED_DPNT +/*XXX TODO this crashes on nios2: it translates to + * [r5] := (value of the local variable dpnt) + * but r5 is a NULL pointer at this place, which was + * retrieved from the GOT a few instructions further above. + */ + _dl_saved_dpnt = dpnt; +#endif __rtld_stack_end = (void *)(argv - 1); _dl_elf_main = (int (*)(int, char **, char **)) diff --git a/ldso/ldso/nios2/dl-startup.h b/ldso/ldso/nios2/dl-startup.h index 982e55532..fb4fc7caf 100644 --- a/ldso/ldso/nios2/dl-startup.h +++ b/ldso/ldso/nios2/dl-startup.h @@ -1,13 +1,86 @@ -__asm__ ("\ - .text\n\ - .globl _start\n\ - .type _start, %function\n\ -_start:\n\ - mov r4, sp\n\ - br _dl_start\n\ - mov r16, r4\n\ - jmp r16\n\ -"); +#define LDSO_NEED_DPNT + +unsigned int _dl_nios2_get_gp_value(ElfW(Dyn) *dpnt); + +unsigned int +_dl_nios2_get_gp_value (ElfW(Dyn) *dpnt) +{ + while (dpnt->d_tag != DT_NULL) { + if (dpnt->d_tag == DT_NIOS2_GP) { + return (unsigned int)(dpnt->d_un.d_ptr); + } + ++dpnt; + } + return 0; +} + +__asm__ ( +".text\n" +".globl _start\n" +".type _start, %function\n" +"_start:\n" +" /* At start time, all the args are on the stack. */\n" +" mov r4, sp\n" +"\n" +" /* Start the calculation of the GOT pointer. */\n" +" nextpc r22\n" +"1: movhi r8, %hiadj(_gp_got - 1b)\n" +" addi r8, r8, %lo(_gp_got - 1b)\n" +"\n" +" /* Figure out where _dl_start will need to return to. */\n" +" movhi ra, %hiadj(2f - 1b)\n" +" addi ra, ra, %lo(2f - 1b)\n" +" add ra, ra, r22\n" +"\n" +" /* Finish the calculation of the GOT pointer. */\n" +" add r22, r22, r8\n" +"\n" +" br _dl_start\n" +"\n" +" /* Save the returned user entry point. */\n" +"2: mov r16, r2\n" +"\n" +" /* Initialize gp. */\n" +" ldw r4, %got(_dl_saved_dpnt)(r22)\n" +" ldw r8, %call(_dl_nios2_get_gp_value)(r22)\n" +" callr r8\n" +" mov gp, r2\n" +"\n" +" /* Find the number of arguments to skip. */\n" +" ldw r8, %got(_dl_skip_args)(r22)\n" +" ldw r8, 0(r8)\n" +"\n" +" /* Find argc. */\n" +" ldw r5, 0(sp)\n" +" sub r5, r5, r8\n" +" stw r5, 0(sp)\n" +"\n" +" /* Find the first unskipped argument. */\n" +" slli r8, r8, 2\n" +" addi r6, sp, 4\n" +" add r9, r6, r8\n" +" mov r10, r6\n" +"\n" +" /* Shuffle envp down. */\n" +" mov r7, r10\n" +"3: ldw r11, 0(r9)\n" +" stw r11, 0(r10)\n" +" addi r9, r9, 4\n" +" addi r10, r10, 4\n" +" bne r11, zero, 3b\n" +"\n" +" /* Shuffle auxv down. */\n" +"4: ldw r11, 4(r9)\n" +" stw r11, 4(r10)\n" +" ldw r11, 0(r9)\n" +" stw r11, 0(r10)\n" +" addi r9, r9, 8\n" +" addi r10, r10, 8\n" +" bne r11, zero, 4b\n" +"\n" +" /* Jump to the user's entry point. */\n" +" jmp r16\n" +); /* * Get a pointer to the argv array. On many platforms this can be just @@ -16,6 +89,9 @@ _start:\n\ */ #define GET_ARGV(ARGVP, ARGS) ARGVP = (((unsigned long*) ARGS)+1) +/* We can't call functions earlier in the dl startup process */ +#define NO_FUNCS_BEFORE_BOOTSTRAP + /* The ld.so library requires relocations */ #define ARCH_NEEDS_BOOTSTRAP_RELOCS -- cgit v1.2.3