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* Make changing the PLT slot entry (lazy function binding) thread-safe.

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* Insert `iflush' instructions for the patched words in PLT entries.
This commit is contained in:
pk 1999-02-27 17:12:13 +00:00
parent f008a1bbd0
commit e81b9ed433
1 changed files with 11 additions and 5 deletions
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16
libexec/ld.elf_so/arch/sparc/mdreloc.c
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@ -1,4 +1,4 @@
/* $NetBSD: mdreloc.c,v 1.5 1999/02/27 11:36:02 pk Exp $ */ /* $NetBSD: mdreloc.c,v 1.6 1999/02/27 17:12:13 pk Exp $ */
/*- /*-
* Copyright (c) 1999 The NetBSD Foundation, Inc. * Copyright (c) 1999 The NetBSD Foundation, Inc.
@ -297,16 +297,22 @@ _rtld_relocate_plt_object(
* a direct transfer to the now fully resolved function * a direct transfer to the now fully resolved function
* address. The resulting code in the jump slot is: * address. The resulting code in the jump slot is:
* *
* sethi %hi(roffset), %g1
* sethi %hi(addr), %g1 * sethi %hi(addr), %g1
* jmp %g1+%lo(addr) * jmp %g1+%lo(addr)
* nop ! delay slot *
* We write the third instruction first, since that leaves the
* previous `b,a' at the second word in place. Hence the whole
* PLT slot can be atomically change to the new sequence by
* writing the `sethi' instruction at word 2.
*/ */
#define SETHI 0x03000000 #define SETHI 0x03000000
#define JMP 0x81c06000 #define JMP 0x81c06000
#define NOP 0x01000000 #define NOP 0x01000000
where[0] = SETHI | ((value >> 10) & 0x003fffff); where[2] = JMP | (value & 0x000003ff);
where[1] = JMP | (value & 0x000003ff); where[1] = SETHI | ((value >> 10) & 0x003fffff);
where[2] = NOP; __asm __volatile("iflush %0+8" : : "r" (where));
__asm __volatile("iflush %0+4" : : "r" (where));
if (addrp != NULL) if (addrp != NULL)
*addrp = (caddr_t)value; *addrp = (caddr_t)value;