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authorWaldemar Brodkorb <wbx@openadk.org>2017-03-25 17:12:28 (GMT)
committerWaldemar Brodkorb <wbx@openadk.org>2017-04-01 19:00:37 (GMT)
commitb30bd74dbcc48aca94b10531bb3056c5ef401752 (patch)
tree8555efc83fedd29e25f8352e855837917f9c8981
parent9881defed03814471179e4395e0e79ddfcce6661 (diff)
nios2: allow to hack on experimenting ld.so support
-rw-r--r--extra/Configs/Config.nios21
-rw-r--r--ldso/ldso/dl-startup.c12
-rw-r--r--ldso/ldso/nios2/dl-startup.h96
3 files changed, 98 insertions, 11 deletions
diff --git a/extra/Configs/Config.nios2 b/extra/Configs/Config.nios2
index 958607c..8fcb01b 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 87f564f..218b20f 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 982e555..fb4fc7c 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