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Thu Jun 20 21:19:07 1996 Richard Henderson <rth@tamu.edu> 

* sysdeps/alpha/dl-machine.h (elf_alpha_fix_plt):
	Changed to a 12-byte PLT entry to remove dependency on $gp.
	Take a new got_addr parameter.
	(elf_machine_rela): Pass the new parameter.
	(ELF_MACHINE_RUNTIME_TRAMPOLINE): Do arithmetic for 12-byte PLT.
	(RTLD_START): Do normal linkage with program entry.
This commit is contained in:
Roland McGrath 1996-06-21 04:30:50 +00:00
parent 51ec5cb28a
commit 7b5092a79d
1 changed files with 39 additions and 17 deletions
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56
sysdeps/alpha/dl-machine.h
View File

@ -1,7 +1,7 @@
/* Machine-dependent ELF dynamic relocation inline functions. Alpha version.
Copyright (C) 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Richard Henderson <rht@tamu.edu>.
Contributed by Richard Henderson <rth@tamu.edu>.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
@ -84,42 +84,64 @@ elf_machine_load_address (void)
static inline void
elf_alpha_fix_plt(struct link_map *l,
const Elf64_Rela *reloc,
Elf64_Addr got_addr,
Elf64_Addr value)
{
const Elf64_Rela *rela_plt;
Elf64_Word *plte;
long disp;
long edisp;
/* Recover the PLT entry address by calculating reloc's index into the
.rela.plt, and finding that entry in the .plt. */
rela_plt = (void *)(l->l_addr + l->l_info[DT_JMPREL]->d_un.d_ptr);
plte = (void *)(l->l_addr + l->l_info[DT_PLTGOT]->d_un.d_ptr);
plte += 2*(reloc - rela_plt) + 8;
plte = (void *)(l->l_addr + l->l_info[DT_PLTGOT]->d_un.d_ptr + 32);
plte += 3 * (reloc - rela_plt);
/* Find the displacement from the plt entry to the function. */
disp = value - (Elf64_Addr)&plte[2];
edisp = (long)(value - (Elf64_Addr)&plte[3]) / 4;
/* Change "lda $27, ofs($31)" to "ldq $27, ofs($gp)" */
plte[0] = 0xa77d0000 | (plte[0] & 0xffff);
if (disp >= -0x100000 && disp < 0x100000)
if (edisp >= -0x100000 && edisp < 0x100000)
{
/* If we are in range, use br to perfect branch prediction and
elide the dependancy on the address load. This case happens,
e.g., when a shared library call is resolved to the same library. */
/* Change "br $0, plt0" to "br $31,function" */
plte[1] = 0xc3e00000 | (disp & 0x1fffff);
int hi, lo;
hi = value - (Elf64_Addr)&plte[0];
lo = (short)hi;
hi = (hi - lo) >> 16;
/* Emit "ldah $27,H($27)" */
plte[0] = 0x277b0000 | (hi & 0xffff);
/* Emit "lda $27,L($27)" */
plte[1] = 0x237b0000 | (lo & 0xffff);
/* Emit "br $31,function" */
plte[2] = 0xc3e00000 | (edisp & 0x1fffff);
}
else
{
/* Don't bother with the hint since we already know the hint is
wrong. Eliding it prevents the wrong page from getting pulled
into the cache. */
/* Change "br $0, plt0" to "jmp $31,($27)" */
plte[1] = 0x6bfb0000;
int hi, lo;
hi = got_addr - (Elf64_Addr)&plte[0];
lo = (short)hi;
hi = (hi - lo) >> 16;
/* Emit "ldah $27,H($27)" */
plte[0] = 0x277b0000 | (hi & 0xffff);
/* Emit "ldq $27,L($27)" */
plte[1] = 0xa77b0000 | (lo & 0xffff);
/* Emit "jmp $31,($27)" */
plte[2] = 0x6bfb0000;
}
/* Flush the instruction cache now that we've diddled. Tag it as
@ -172,7 +194,7 @@ elf_machine_rela (struct link_map *map,
else if (r_info == R_ALPHA_JMP_SLOT)
{
*reloc_addr = sym_value;
elf_alpha_fix_plt(map, reloc, sym_value);
elf_alpha_fix_plt(map, reloc, (Elf64_Addr)reloc_addr, sym_value);
}
else if (r_info == R_ALPHA_REFQUAD)
{
@ -285,11 +307,10 @@ _dl_runtime_resolve:
/* Set up the arguments for _dl_runtime_resolve. */
/* $16 = link_map out of plt0 */
ldq $16, 8($27)
/* $17 = (($0 - 8) - ($1 + 16)) / 8 * sizeof(Elf_Rela) */
/* $17 = (($28 - 4) - ($27 + 16)) / 12 * sizeof(Elf_Rela) */
subq $28, $27, $28
subq $28, 24, $28
subq $28, 20, $28
addq $28, $28, $17
addq $28, $17, $17
/* Do the fixup */
bsr $26, fixup..ng
/* Move the destination address to a safe place. */
@ -370,4 +391,5 @@ _dl_start_user:
2: /* Pass our finalizer function to the user in $0. */
lda $0, _dl_fini
/* Jump to the user's entry point. */
mov $9, $27
jmp ($9)");