307 lines
9.7 KiB
Diff
307 lines
9.7 KiB
Diff
When building glibc PIE (which is not something upstream support),
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several modifications are necessary to the glibc build process.
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First, any syscalls in PIEs must be of the PIC variant, otherwise
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textrels ensue. Then, any syscalls made before the initialisation
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of the TLS will fail on i386, as the sysenter variant on i386 uses
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the TLS, giving rise to a chicken-and-egg situation. This patch
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defines a PIC syscall variant that doesn't use sysenter, even when the sysenter
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version is normally used, and uses the non-sysenter version for the brk
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syscall that is performed by the TLS initialisation. Further, the TLS
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initialisation is moved in this case prior to the initialisation of
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dl_osversion, as that requires further syscalls.
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csu/libc-start.c: Move initial TLS initialization to before the
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initialisation of dl_osversion, when INTERNAL_SYSCALL_PRE_TLS is defined
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csu/libc-tls.c: Use the no-sysenter version of sbrk when
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INTERNAL_SYSCALL_PRE_TLS is defined.
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misc/sbrk.c: Define a no-sysenter version of sbrk, using the no-sysenter
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version of brk - if INTERNAL_SYSCALL_PRE_TLS is defined.
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misc/brk.c: Define a no-sysenter version of brk if
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INTERNAL_SYSCALL_PRE_TLS is defined.
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sysdeps/unix/sysv/linux/i386/sysdep.h: Define INTERNAL_SYSCALL_PRE_TLS
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Make INTERNAL_SYSCALL always use the PIC variant, even if not SHARED.
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Patch by Kevin F. Quinn <kevquinn@gentoo.org>
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Fixed for 2.10 by Magnus Granberg <zorry@ume.nu>
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Fixed for 2.18 by Magnus Granberg <zorry@gentoo.org>
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Fixed for 2.20 by Francisco Blas Izquierdo Riera <klondike@gentoo.org>
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--- a/csu/libc-start.c
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+++ b/csu/libc-start.c
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@@ -28,6 +28,7 @@
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extern int __libc_multiple_libcs;
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#include <tls.h>
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+#include <sysdep.h>
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#ifndef SHARED
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# include <dl-osinfo.h>
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extern void __pthread_initialize_minimal (void);
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@@ -170,6 +171,11 @@ LIBC_START_MAIN (int (*main) (int, char
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}
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}
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+# ifdef INTERNAL_SYSCALL_PRE_TLS
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+ /* Do the initial TLS initialization before _dl_osversion,
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+ since the latter uses the uname syscall. */
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+ __pthread_initialize_minimal ();
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+# endif
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# ifdef DL_SYSDEP_OSCHECK
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if (!__libc_multiple_libcs)
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{
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@@ -138,10 +144,12 @@
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}
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# endif
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+# ifndef INTERNAL_SYSCALL_PRE_TLS
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/* Initialize the thread library at least a bit since the libgcc
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functions are using thread functions if these are available and
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we need to setup errno. */
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__pthread_initialize_minimal ();
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+# endif
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/* Set up the stack checker's canary. */
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uintptr_t stack_chk_guard = _dl_setup_stack_chk_guard ();
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--- a/csu/libc-tls.c
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+++ b/csu/libc-tls.c
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@@ -22,12 +22,17 @@
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#include <unistd.h>
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#include <stdio.h>
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#include <sys/param.h>
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+#include <sysdep.h>
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#ifdef SHARED
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#error makefile bug, this file is for static only
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#endif
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+#ifdef INTERNAL_SYSCALL_PRE_TLS
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+extern void *__sbrk_nosysenter (intptr_t __delta);
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+#endif
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+
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dtv_t _dl_static_dtv[2 + TLS_SLOTINFO_SURPLUS];
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@@ -139,20 +144,29 @@ __libc_setup_tls (size_t tcbsize, size_t
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The initialized value of _dl_tls_static_size is provided by dl-open.c
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to request some surplus that permits dynamic loading of modules with
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- IE-model TLS. */
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+ IE-model TLS.
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+
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+ Where the normal sbrk would use a syscall that needs the TLS (i386)
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+ use the special non-sysenter version instead. */
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+#ifdef INTERNAL_SYSCALL_PRE_TLS
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+# define __sbrk __sbrk_nosysenter
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+#endif
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#if TLS_TCB_AT_TP
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tcb_offset = roundup (memsz + GL(dl_tls_static_size), tcbalign);
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tlsblock = __sbrk (tcb_offset + tcbsize + max_align);
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#elif TLS_DTV_AT_TP
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tcb_offset = roundup (tcbsize, align ?: 1);
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tlsblock = __sbrk (tcb_offset + memsz + max_align
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+ TLS_PRE_TCB_SIZE + GL(dl_tls_static_size));
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tlsblock += TLS_PRE_TCB_SIZE;
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#else
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/* In case a model with a different layout for the TCB and DTV
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is defined add another #elif here and in the following #ifs. */
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# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
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#endif
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+#ifdef INTERNAL_SYSCALL_PRE_TLS
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+# undef __sbrk
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+#endif
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/* Align the TLS block. */
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tlsblock = (void *) (((uintptr_t) tlsblock + max_align - 1)
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--- a/misc/sbrk.c
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+++ b/misc/sbrk.c
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@@ -18,6 +18,7 @@
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#include <errno.h>
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#include <stdint.h>
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#include <unistd.h>
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+#include <sysdep.h>
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/* Defined in brk.c. */
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extern void *__curbrk;
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@@ -29,6 +30,35 @@
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/* Extend the process's data space by INCREMENT.
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If INCREMENT is negative, shrink data space by - INCREMENT.
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Return start of new space allocated, or -1 for errors. */
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+#ifdef INTERNAL_SYSCALL_PRE_TLS
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+/* This version is used by csu/libc-tls.c whem initialising the TLS
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+ if the SYSENTER version requires the TLS (which it does on i386).
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+ Obviously using the TLS before it is initialised is broken. */
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+extern int __brk_nosysenter (void *addr);
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+void *
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+__sbrk_nosysenter (intptr_t increment)
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+{
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+ void *oldbrk;
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+
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+ /* If this is not part of the dynamic library or the library is used via
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+ dynamic loading in a statically linked program update __curbrk from the
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+ kernel's brk value. That way two separate instances of __brk and __sbrk
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+ can share the heap, returning interleaved pieces of it. */
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+ if (__curbrk == NULL || __libc_multiple_libcs)
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+ if (__brk_nosysenter (0) < 0) /* Initialize the break. */
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+ return (void *) -1;
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+
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+ if (increment == 0)
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+ return __curbrk;
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+
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+ oldbrk = __curbrk;
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+ if (__brk_nosysenter (oldbrk + increment) < 0)
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+ return (void *) -1;
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+
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+ return oldbrk;
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+}
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+#endif
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+
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void *
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__sbrk (intptr_t increment)
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{
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--- a/sysdeps/unix/sysv/linux/i386/brk.c
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+++ b/sysdeps/unix/sysv/linux/i386/brk.c
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@@ -31,6 +31,30 @@
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linker. */
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weak_alias (__curbrk, ___brk_addr)
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+#ifdef INTERNAL_SYSCALL_PRE_TLS
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+/* This version is used by csu/libc-tls.c whem initialising the TLS
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+ if the SYSENTER version requires the TLS (which it does on i386).
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+ Obviously using the TLS before it is initialised is broken. */
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+int
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+__brk_nosysenter (void *addr)
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+{
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+ void *newbrk;
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+
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+ INTERNAL_SYSCALL_DECL (err);
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+ newbrk = (void *) INTERNAL_SYSCALL_PRE_TLS (brk, err, 1, addr);
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+
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+ __curbrk = newbrk;
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+
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+ if (newbrk < addr)
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+ {
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+ __set_errno (ENOMEM);
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+ return -1;
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+ }
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+
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+ return 0;
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+}
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+#endif
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+
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int
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__brk (void *addr)
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{
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--- a/sysdeps/unix/sysv/linux/i386/sysdep.h
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+++ b/sysdeps/unix/sysv/linux/i386/sysdep.h
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@@ -187,7 +187,7 @@
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/* The original calling convention for system calls on Linux/i386 is
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to use int $0x80. */
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#ifdef I386_USE_SYSENTER
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-# ifdef SHARED
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+# ifdef __PIC__
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# define ENTER_KERNEL call *%gs:SYSINFO_OFFSET
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# else
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# define ENTER_KERNEL call *_dl_sysinfo
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@@ -358,7 +358,7 @@
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possible to use more than four parameters. */
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#undef INTERNAL_SYSCALL
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#ifdef I386_USE_SYSENTER
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-# ifdef SHARED
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+# ifdef __PIC__
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# define INTERNAL_SYSCALL(name, err, nr, args...) \
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({ \
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register unsigned int resultvar; \
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@@ -384,6 +384,18 @@
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: "0" (name), "i" (offsetof (tcbhead_t, sysinfo)) \
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ASMFMT_##nr(args) : "memory", "cc"); \
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(int) resultvar; })
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+# define INTERNAL_SYSCALL_PRE_TLS(name, err, nr, args...) \
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+ ({ \
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+ register unsigned int resultvar; \
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+ EXTRAVAR_##nr \
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+ asm volatile ( \
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+ LOADARGS_NOSYSENTER_##nr \
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+ "movl %1, %%eax\n\t" \
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+ "int $0x80\n\t" \
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+ RESTOREARGS_NOSYSENTER_##nr \
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+ : "=a" (resultvar) \
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+ : "i" (__NR_##name) ASMFMT_##nr(args) : "memory", "cc"); \
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+ (int) resultvar; })
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# else
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# define INTERNAL_SYSCALL(name, err, nr, args...) \
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({ \
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@@ -447,12 +459,20 @@
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#define LOADARGS_0
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#ifdef __PIC__
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-# if defined I386_USE_SYSENTER && defined SHARED
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+# if defined I386_USE_SYSENTER && defined __PIC__
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# define LOADARGS_1 \
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"bpushl .L__X'%k3, %k3\n\t"
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# define LOADARGS_5 \
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"movl %%ebx, %4\n\t" \
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"movl %3, %%ebx\n\t"
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+# define LOADARGS_NOSYSENTER_1 \
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+ "bpushl .L__X'%k2, %k2\n\t"
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+# define LOADARGS_NOSYSENTER_2 LOADARGS_NOSYSENTER_1
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+# define LOADARGS_NOSYSENTER_3 LOADARGS_3
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+# define LOADARGS_NOSYSENTER_4 LOADARGS_3
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+# define LOADARGS_NOSYSENTER_5 \
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+ "movl %%ebx, %3\n\t" \
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+ "movl %2, %%ebx\n\t"
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# else
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# define LOADARGS_1 \
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"bpushl .L__X'%k2, %k2\n\t"
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@@ -474,11 +494,18 @@
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#define RESTOREARGS_0
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#ifdef __PIC__
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-# if defined I386_USE_SYSENTER && defined SHARED
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+# if defined I386_USE_SYSENTER && defined __PIC__
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# define RESTOREARGS_1 \
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"bpopl .L__X'%k3, %k3\n\t"
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# define RESTOREARGS_5 \
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"movl %4, %%ebx"
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+# define RESTOREARGS_NOSYSENTER_1 \
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+ "bpopl .L__X'%k2, %k2\n\t"
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+# define RESTOREARGS_NOSYSENTER_2 RESTOREARGS_NOSYSENTER_1
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+# define RESTOREARGS_NOSYSENTER_3 RESTOREARGS_3
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+# define RESTOREARGS_NOSYSENTER_4 RESTOREARGS_3
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+# define RESTOREARGS_NOSYSENTER_5 \
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+ "movl %3, %%ebx"
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# else
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# define RESTOREARGS_1 \
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"bpopl .L__X'%k2, %k2\n\t"
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--- a/sysdeps/i386/nptl/tls.h
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+++ b/sysdeps/i386/nptl/tls.h
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@@ -189,6 +189,15 @@
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desc->vals[3] = 0x51;
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}
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+/* We have no sysenter until the tls is initialized which is a
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+ problem for PIC. Thus we need to do the right call depending
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+ on the situation. */
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+#ifndef INTERNAL_SYSCALL_PRE_TLS
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+# define TLS_INIT_SYSCALL INTERNAL_SYSCALL
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+#else
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+# define TLS_INIT_SYSCALL INTERNAL_SYSCALL_PRE_TLS
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+#endif
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+
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/* Code to initially initialize the thread pointer. This might need
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special attention since 'errno' is not yet available and if the
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operation can cause a failure 'errno' must not be touched. */
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@@ -209,7 +218,7 @@
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\
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/* Install the TLS. */ \
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INTERNAL_SYSCALL_DECL (err); \
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- _result = INTERNAL_SYSCALL (set_thread_area, err, 1, &_segdescr.desc); \
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+ _result = TLS_INIT_SYSCALL (set_thread_area, err, 1, &_segdescr.desc); \
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\
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if (_result == 0) \
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/* We know the index in the GDT, now load the segment register. \
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