[uClibc] getting ldso to work on sparc-linux
Jakub Bogusz
qboosh at pld-linux.org
Sat Jun 5 13:16:24 UTC 2004
Hello,
I managed to get ldso (and thus shared linking to uClibc) to work on
sparc (actually sparc64 kernel with 32-bit userspace), at least on
simple "hello world" program (more complex ones not tested).
Some notes on attached patch (against 0.9.26, would require some work
to apply on current CVS - but I tested 0.9.26, not CVS):
- ELF magic cannot be examined by _dl_strncmp so early, probably because of
string constant, like on ppc/mips/sh
(note that early SEND_STDERR still crashes when trying to do _dl_strlen
- I suppose that string constants require relocation; but adding
load_addr didn't help, just ELF header was displayed instead of crash)
- mmap() is syscall6 like on ppc/mips/sh, not old i386 mmap()
- for generic sparc (i.e. not sparcv8/sparcv9) gcc produces .udiv/.urem
calls for unsigned integer / and % operators - so these operations
must be avoided. I copied do_rem definition from arm header.
But / and % are used also in _dl_simple_ltoa() and
_dl_simple_ltoahex(); in ltoahex gcc optimizes it to shifts (but
I think it's safer to use shifts explicitly, not rely on
optimization...).
I changed % in ltoa to do_rem, but as there was no do_div definition,
I changed all "%d" specifiers to "%x" to avoid crashes (this changes
wouldn't be needed if _dl_simple_ltoa() were fixed to not use
division on sparc).
- "#define SOLARIS_COMPATIBLE" in ld_sysdep.h broke ldso on Linux
because of redefining _dl_linux_resolve only in some places (it was
still referenced in INIT_GOT before redefinition). So
_dl_linux_resolve redefinition should be moved before INIT_GOT
definition or removed.
- sparc64 kernel requires mmap() addresses to be aligned to 8192, not
4096, otherwise mmap() call failed
- reloc_entry must be shifted by 10, not 12 (I found similar operation
in glibc sources)
Aside of sparc-specific fixes:
- I moved some _dl_dprintf()s inside if(_dl_debug_*) conditions (to avoid
debugging messages when LD_DEBUG is not defined)
- it seems that there was possible off-by-one in ltoa and ltoahex?
they are called with char[22] as 1st argument, and then '\0' is stored
in local[22] (_before_ p decrementation)... or am I missing something?
If not, fix is included in patch.
--
Jakub Bogusz http://cyber.cs.net.pl/~qboosh/
-------------- next part --------------
--- uClibc-0.9.26/ldso/include/ld_string.h.orig 2003-09-29 21:46:00.000000000 +0000
+++ uClibc-0.9.26/ldso/include/ld_string.h 2004-05-27 20:47:48.000000000 +0000
@@ -215,11 +215,13 @@
static inline char *_dl_simple_ltoa(char * local, unsigned long i)
{
/* 21 digits plus null terminator, good for 64-bit or smaller ints */
- char *p = &local[22];
+ char *p = &local[21];
*p-- = '\0';
do {
- *p-- = '0' + i % 10;
- i /= 10;
+ char temp;
+ do_rem(temp, i, 10);
+ *p-- = '0' + temp;
+ i /= 10; /* XXX: .udiv() on sparc! */
} while (i > 0);
return p + 1;
}
@@ -227,15 +229,15 @@
static inline char *_dl_simple_ltoahex(char * local, unsigned long i)
{
/* 21 digits plus null terminator, good for 64-bit or smaller ints */
- char *p = &local[22];
+ char *p = &local[21];
*p-- = '\0';
do {
- char temp = i % 0x10;
+ char temp = i & 0xf; /* % 0x10, to be sure .urem is not used */
if (temp <= 0x09)
*p-- = '0' + temp;
else
*p-- = 'a' - 0x0a + temp;
- i /= 0x10;
+ i >>= 4; /* /= 0x10, to be sure .udiv is not used */
} while (i > 0);
*p-- = 'x';
*p-- = '0';
--- uClibc-0.9.26/ldso/include/ld_syscall.h.orig 2003-08-19 06:05:30.000000000 +0000
+++ uClibc-0.9.26/ldso/include/ld_syscall.h 2004-05-25 22:20:36.000000000 +0000
@@ -50,7 +50,7 @@
static inline _syscall1(int, _dl_close, int, fd);
-#if defined(__powerpc__) || defined(__mips__) || defined(__sh__)
+#if defined(__powerpc__) || defined(__mips__) || defined(__sh__) || defined(__sparc__)
/* PowerPC, MIPS and SuperH have a different calling convention for mmap(). */
#define __NR__dl_mmap __NR_mmap
static inline _syscall6(void *, _dl_mmap, void *, start, size_t, length,
--- uClibc-0.9.26/ldso/ldso/sparc/ld_syscalls.h.orig 2004-05-25 19:03:47.000000000 +0000
+++ uClibc-0.9.26/ldso/ldso/sparc/ld_syscalls.h 2004-05-25 22:41:08.000000000 +0000
@@ -154,3 +154,29 @@
/*errno = -__res; */\
return -1; \
}
+
+#define _syscall6(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4, \
+ type5,arg5,type6,arg6) \
+type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5,type6 arg6) \
+{ \
+long __res; \
+register long __g1 __asm__ ("g1") = __NR_##name; \
+register long __o0 __asm__ ("o0") = (long)(arg1); \
+register long __o1 __asm__ ("o1") = (long)(arg2); \
+register long __o2 __asm__ ("o2") = (long)(arg3); \
+register long __o3 __asm__ ("o3") = (long)(arg4); \
+register long __o4 __asm__ ("o4") = (long)(arg5); \
+register long __o5 __asm__ ("o5") = (long)(arg6); \
+__asm__ __volatile__ ("t 0x10\n\t" \
+ "bcc 1f\n\t" \
+ "mov %%o0, %0\n\t" \
+ "sub %%g0, %%o0, %0\n\t" \
+ "1:\n\t" \
+ : "=r" (__res), "=&r" (__o0) \
+ : "1" (__o0), "r" (__o1), "r" (__o2), "r" (__o3), "r" (__o4), "r" (__o5), "r" (__g1) \
+ : "cc"); \
+if (__res < -255 || __res>=0) \
+ return (type) __res; \
+/*errno = -__res; */\
+return -1; \
+}
--- uClibc-0.9.26/ldso/ldso/sparc/ld_sysdep.h.orig 2003-12-17 08:05:44.000000000 +0000
+++ uClibc-0.9.26/ldso/ldso/sparc/ld_sysdep.h 2004-05-27 19:41:50.000000000 +0000
@@ -95,9 +95,51 @@
/*
* Define this if you want a dynamic loader that works on Solaris.
*/
+#ifndef __linux__
#define SOLARIS_COMPATIBLE
+#endif
+
+#ifndef COMPILE_ASM
+/* Cheap modulo implementation, taken from arm/ld_sysdep.h. */
+static inline unsigned long
+sparc_mod(unsigned long m, unsigned long p)
+{
+ unsigned long i, t, inc;
+
+ i = p;
+ t = 0;
+
+ while (!(i & (1 << 31))) {
+ i <<= 1;
+ t++;
+ }
+
+ t--;
+
+ for (inc = t; inc > 2; inc--) {
+ i = p << inc;
+
+ if (i & (1 << 31))
+ break;
+
+ while (m >= i) {
+ m -= i;
+ i <<= 1;
+ if (i & (1 << 31))
+ break;
+ if (i < p)
+ break;
+ }
+ }
+
+ while (m >= p)
+ m -= p;
+
+ return m;
+}
-#define do_rem(result, n, base) result = (n % base)
+#define do_rem(result, n, base) result = sparc_mod(n, base);
+#endif
/*
* dbx wants the binder to have a specific name. Mustn't disappoint it.
@@ -107,6 +149,7 @@
#endif
/* 4096 bytes alignment */
-#define PAGE_ALIGN 0xfffff000
-#define ADDR_ALIGN 0xfff
-#define OFFS_ALIGN 0x7ffff000
+/* ...but 8192 is required for mmap() on sparc64 kernel */
+#define PAGE_ALIGN 0xffffe000
+#define ADDR_ALIGN 0x1fff
+#define OFFS_ALIGN 0x7fffe000
--- uClibc-0.9.26/ldso/ldso/sparc/elfinterp.c.orig 2004-05-25 19:03:47.000000000 +0000
+++ uClibc-0.9.26/ldso/ldso/sparc/elfinterp.c 2004-05-27 19:16:15.000000000 +0000
@@ -72,7 +72,7 @@
/*
* Generate the correct relocation index into the .rela.plt section.
*/
- reloc_entry = (reloc_entry >> 12) - 0xc;
+ reloc_entry = (reloc_entry >> 10) - 0xc;
this_reloc = (Elf32_Rela *) ((char *) rel_addr + reloc_entry);
@@ -82,10 +82,14 @@
symtab = (Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);
+#ifdef __SUPPORT_LD_DEBUG__
+ if (_dl_debug_symbols) {
_dl_dprintf(2, "tpnt = %x\n", tpnt);
_dl_dprintf(2, "reloc = %x\n", this_reloc);
_dl_dprintf(2, "symtab = %x\n", symtab);
_dl_dprintf(2, "strtab = %x\n", strtab);
+ }
+#endif
if (reloc_type != R_SPARC_JMP_SLOT) {
@@ -98,10 +102,10 @@
instr_addr = ((int)this_reloc->r_offset + (int)tpnt->loadaddr);
got_addr = (char **) instr_addr;
- _dl_dprintf(2, "symtab_index %d\n", symtab_index);
-
#ifdef __SUPPORT_LD_DEBUG__
if (_dl_debug_symbols) {
+ _dl_dprintf(2, "symtab_index %x\n", symtab_index);
+
_dl_dprintf(2, "Resolving symbol %s\n",
strtab + symtab[symtab_index].st_name);
}
--- uClibc-0.9.26/ldso/ldso/ldso.c.orig 2004-05-25 19:03:47.000000000 +0000
+++ uClibc-0.9.26/ldso/ldso/ldso.c 2004-05-25 21:27:59.000000000 +0000
@@ -253,7 +253,7 @@
/* Check the ELF header to make sure everything looks ok. */
if (!header || header->e_ident[EI_CLASS] != ELFCLASS32 ||
header->e_ident[EI_VERSION] != EV_CURRENT
-#if !defined(__powerpc__) && !defined(__mips__) && !defined(__sh__)
+#if !defined(__powerpc__) && !defined(__mips__) && !defined(__sh__) && !defined(__sparc__)
|| _dl_strncmp((void *) header, ELFMAGIC, SELFMAG) != 0
#else
|| header->e_ident[EI_MAG0] != ELFMAG0
--- uClibc-0.9.26/ldso/ldso/readelflib1.c.orig 2003-12-17 18:34:15.000000000 +0000
+++ uClibc-0.9.26/ldso/ldso/readelflib1.c 2004-05-27 20:41:34.000000000 +0000
@@ -725,7 +725,7 @@
_dl_dprintf(2, "\n\tfile='%s'; generating link map\n", libname);
_dl_dprintf(2, "\t\tdynamic: %x base: %x size: %x\n",
dynamic_addr, libaddr, dynamic_size);
- _dl_dprintf(2, "\t\t entry: %x phdr: %x phnum: %d\n\n",
+ _dl_dprintf(2, "\t\t entry: %x phdr: %x phnum: %x\n\n",
epnt->e_entry + libaddr, tpnt->ppnt, tpnt->n_phent);
}
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