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[PATCH] uml: check for differences in host support

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If running on a host not supporting TLS (for instance 2.4) we should report
that cleanly to the user, instead of printing not comprehensible "error 5" for
that.

Additionally, i386 and x86_64 support different ranges for
user_desc->entry_number, and we must account for that; we couldn't pass
ourselves -1 because we need to override previously existing TLS descriptors
which glibc has possibly set, so test at startup the range to use.

x86 and x86_64 existing ranges are hardcoded.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Paolo 'Blaisorblade' Giarrusso
2006-03-31 02:30:25 -08:00
committed by Linus Torvalds
parent 54d8d3b5a0
commit 3feb88562d
8 changed files with 102 additions and 6 deletions
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2
arch/um/os-Linux/sys-i386/Makefile
View File

@@ -3,7 +3,7 @@
# Licensed under the GPL
#
obj-$(CONFIG_MODE_SKAS) = registers.o
obj-$(CONFIG_MODE_SKAS) = registers.o tls.o
USER_OBJS := $(obj-y)

33
arch/um/os-Linux/sys-i386/tls.c Normal file
View File

@@ -0,0 +1,33 @@
#include <linux/unistd.h>
#include "sysdep/tls.h"
#include "user_util.h"
static _syscall1(int, get_thread_area, user_desc_t *, u_info);
/* Checks whether host supports TLS, and sets *tls_min according to the value
* valid on the host.
* i386 host have it == 6; x86_64 host have it == 12, for i386 emulation. */
void check_host_supports_tls(int *supports_tls, int *tls_min) {
/* Values for x86 and x86_64.*/
int val[] = {GDT_ENTRY_TLS_MIN_I386, GDT_ENTRY_TLS_MIN_X86_64};
int i;
for (i = 0; i < ARRAY_SIZE(val); i++) {
user_desc_t info;
info.entry_number = val[i];
if (get_thread_area(&info) == 0) {
*tls_min = val[i];
*supports_tls = 1;
return;
} else {
if (errno == EINVAL)
continue;
else if (errno == ENOSYS)
*supports_tls = 0;
return;
}
}
*supports_tls = 0;
}

4
arch/um/os-Linux/tls.c
View File

@@ -48,8 +48,8 @@ int os_get_thread_area(user_desc_t *info, int pid)
#ifdef UML_CONFIG_MODE_TT
#include "linux/unistd.h"
_syscall1(int, get_thread_area, user_desc_t *, u_info);
_syscall1(int, set_thread_area, user_desc_t *, u_info);
static _syscall1(int, get_thread_area, user_desc_t *, u_info);
static _syscall1(int, set_thread_area, user_desc_t *, u_info);
int do_set_thread_area_tt(user_desc_t *info)
{