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authorPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>2006-03-31 05:30:25 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-31 15:18:52 -0500
commit3feb88562d149f078319e5a1b2f7acaa10251a5c (patch)
tree73fb00f0ecb9ed0c4cf8eec24c84253ce9620464 /arch/um
parent54d8d3b5a0ce1cdbad1d3154c9ea9732d394e9c7 (diff)
[PATCH] uml: check for differences in host support
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>
Diffstat (limited to 'arch/um')
-rw-r--r--arch/um/include/os.h1
-rw-r--r--arch/um/include/sysdep-i386/tls.h4
-rw-r--r--arch/um/include/user_util.h3
-rw-r--r--arch/um/os-Linux/sys-i386/Makefile2
-rw-r--r--arch/um/os-Linux/sys-i386/tls.c33
-rw-r--r--arch/um/os-Linux/tls.c4
-rw-r--r--arch/um/sys-i386/tls.c55
7 files changed, 97 insertions, 5 deletions
diff --git a/arch/um/include/os.h b/arch/um/include/os.h
index 1b780b5dacbe..f88856c28a66 100644
--- a/arch/um/include/os.h
+++ b/arch/um/include/os.h
@@ -173,6 +173,7 @@ extern int os_fchange_dir(int fd);
173extern void os_early_checks(void); 173extern void os_early_checks(void);
174extern int can_do_skas(void); 174extern int can_do_skas(void);
175extern void os_check_bugs(void); 175extern void os_check_bugs(void);
176extern void check_host_supports_tls(int *supports_tls, int *tls_min);
176 177
177/* Make sure they are clear when running in TT mode. Required by 178/* Make sure they are clear when running in TT mode. Required by
178 * SEGV_MAYBE_FIXABLE */ 179 * SEGV_MAYBE_FIXABLE */
diff --git a/arch/um/include/sysdep-i386/tls.h b/arch/um/include/sysdep-i386/tls.h
index 938f953b26cc..918fd3c5ff9c 100644
--- a/arch/um/include/sysdep-i386/tls.h
+++ b/arch/um/include/sysdep-i386/tls.h
@@ -25,4 +25,8 @@ typedef struct um_dup_user_desc {
25typedef struct user_desc user_desc_t; 25typedef struct user_desc user_desc_t;
26 26
27# endif /* __KERNEL__ */ 27# endif /* __KERNEL__ */
28
29#define GDT_ENTRY_TLS_MIN_I386 6
30#define GDT_ENTRY_TLS_MIN_X86_64 12
31
28#endif /* _SYSDEP_TLS_H */ 32#endif /* _SYSDEP_TLS_H */
diff --git a/arch/um/include/user_util.h b/arch/um/include/user_util.h
index 615f2f0a32d0..fe0c29b5144d 100644
--- a/arch/um/include/user_util.h
+++ b/arch/um/include/user_util.h
@@ -8,6 +8,9 @@
8 8
9#include "sysdep/ptrace.h" 9#include "sysdep/ptrace.h"
10 10
11/* Copied from kernel.h */
12#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
13
11#define CATCH_EINTR(expr) while ((errno = 0, ((expr) < 0)) && (errno == EINTR)) 14#define CATCH_EINTR(expr) while ((errno = 0, ((expr) < 0)) && (errno == EINTR))
12 15
13extern int mode_tt; 16extern int mode_tt;
diff --git a/arch/um/os-Linux/sys-i386/Makefile b/arch/um/os-Linux/sys-i386/Makefile
index 340ef26f5944..b3213613c41c 100644
--- a/arch/um/os-Linux/sys-i386/Makefile
+++ b/arch/um/os-Linux/sys-i386/Makefile
@@ -3,7 +3,7 @@
3# Licensed under the GPL 3# Licensed under the GPL
4# 4#
5 5
6obj-$(CONFIG_MODE_SKAS) = registers.o 6obj-$(CONFIG_MODE_SKAS) = registers.o tls.o
7 7
8USER_OBJS := $(obj-y) 8USER_OBJS := $(obj-y)
9 9
diff --git a/arch/um/os-Linux/sys-i386/tls.c b/arch/um/os-Linux/sys-i386/tls.c
new file mode 100644
index 000000000000..ba21f0e04a2f
--- /dev/null
+++ b/arch/um/os-Linux/sys-i386/tls.c
@@ -0,0 +1,33 @@
1#include <linux/unistd.h>
2#include "sysdep/tls.h"
3#include "user_util.h"
4
5static _syscall1(int, get_thread_area, user_desc_t *, u_info);
6
7/* Checks whether host supports TLS, and sets *tls_min according to the value
8 * valid on the host.
9 * i386 host have it == 6; x86_64 host have it == 12, for i386 emulation. */
10void check_host_supports_tls(int *supports_tls, int *tls_min) {
11 /* Values for x86 and x86_64.*/
12 int val[] = {GDT_ENTRY_TLS_MIN_I386, GDT_ENTRY_TLS_MIN_X86_64};
13 int i;
14
15 for (i = 0; i < ARRAY_SIZE(val); i++) {
16 user_desc_t info;
17 info.entry_number = val[i];
18
19 if (get_thread_area(&info) == 0) {
20 *tls_min = val[i];
21 *supports_tls = 1;
22 return;
23 } else {
24 if (errno == EINVAL)
25 continue;
26 else if (errno == ENOSYS)
27 *supports_tls = 0;
28 return;
29 }
30 }
31
32 *supports_tls = 0;
33}
diff --git a/arch/um/os-Linux/tls.c b/arch/um/os-Linux/tls.c
index 642db553ab60..9cb09a45546b 100644
--- a/arch/um/os-Linux/tls.c
+++ b/arch/um/os-Linux/tls.c
@@ -48,8 +48,8 @@ int os_get_thread_area(user_desc_t *info, int pid)
48#ifdef UML_CONFIG_MODE_TT 48#ifdef UML_CONFIG_MODE_TT
49#include "linux/unistd.h" 49#include "linux/unistd.h"
50 50
51_syscall1(int, get_thread_area, user_desc_t *, u_info); 51static _syscall1(int, get_thread_area, user_desc_t *, u_info);
52_syscall1(int, set_thread_area, user_desc_t *, u_info); 52static _syscall1(int, set_thread_area, user_desc_t *, u_info);
53 53
54int do_set_thread_area_tt(user_desc_t *info) 54int do_set_thread_area_tt(user_desc_t *info)
55{ 55{
diff --git a/arch/um/sys-i386/tls.c b/arch/um/sys-i386/tls.c
index 2251654c6b45..a3188e861cc7 100644
--- a/arch/um/sys-i386/tls.c
+++ b/arch/um/sys-i386/tls.c
@@ -24,6 +24,10 @@
24#include "skas.h" 24#include "skas.h"
25#endif 25#endif
26 26
27/* If needed we can detect when it's uninitialized. */
28static int host_supports_tls = -1;
29int host_gdt_entry_tls_min = -1;
30
27#ifdef CONFIG_MODE_SKAS 31#ifdef CONFIG_MODE_SKAS
28int do_set_thread_area_skas(struct user_desc *info) 32int do_set_thread_area_skas(struct user_desc *info)
29{ 33{
@@ -157,11 +161,20 @@ void clear_flushed_tls(struct task_struct *task)
157 } 161 }
158} 162}
159 163
160/* This in SKAS0 does not need to be used, since we have different host 164/* In SKAS0 mode, currently, multiple guest threads sharing the same ->mm have a
161 * processes. Nor will this need to be used when we'll add support to the host 165 * common host process. So this is needed in SKAS0 too.
166 *
167 * However, if each thread had a different host process (and this was discussed
168 * for SMP support) this won't be needed.
169 *
170 * And this will not need be used when (and if) we'll add support to the host
162 * SKAS patch. */ 171 * SKAS patch. */
172
163int arch_switch_tls_skas(struct task_struct *from, struct task_struct *to) 173int arch_switch_tls_skas(struct task_struct *from, struct task_struct *to)
164{ 174{
175 if (!host_supports_tls)
176 return 0;
177
165 /* We have no need whatsoever to switch TLS for kernel threads; beyond 178 /* We have no need whatsoever to switch TLS for kernel threads; beyond
166 * that, that would also result in us calling os_set_thread_area with 179 * that, that would also result in us calling os_set_thread_area with
167 * userspace_pid[cpu] == 0, which gives an error. */ 180 * userspace_pid[cpu] == 0, which gives an error. */
@@ -173,6 +186,9 @@ int arch_switch_tls_skas(struct task_struct *from, struct task_struct *to)
173 186
174int arch_switch_tls_tt(struct task_struct *from, struct task_struct *to) 187int arch_switch_tls_tt(struct task_struct *from, struct task_struct *to)
175{ 188{
189 if (!host_supports_tls)
190 return 0;
191
176 if (needs_TLS_update(to)) 192 if (needs_TLS_update(to))
177 return load_TLS(0, to); 193 return load_TLS(0, to);
178 194
@@ -256,6 +272,9 @@ asmlinkage int sys_set_thread_area(struct user_desc __user *user_desc)
256 struct user_desc info; 272 struct user_desc info;
257 int idx, ret; 273 int idx, ret;
258 274
275 if (!host_supports_tls)
276 return -ENOSYS;
277
259 if (copy_from_user(&info, user_desc, sizeof(info))) 278 if (copy_from_user(&info, user_desc, sizeof(info)))
260 return -EFAULT; 279 return -EFAULT;
261 280
@@ -287,6 +306,9 @@ int ptrace_set_thread_area(struct task_struct *child, int idx,
287{ 306{
288 struct user_desc info; 307 struct user_desc info;
289 308
309 if (!host_supports_tls)
310 return -EIO;
311
290 if (copy_from_user(&info, user_desc, sizeof(info))) 312 if (copy_from_user(&info, user_desc, sizeof(info)))
291 return -EFAULT; 313 return -EFAULT;
292 314
@@ -298,6 +320,9 @@ asmlinkage int sys_get_thread_area(struct user_desc __user *user_desc)
298 struct user_desc info; 320 struct user_desc info;
299 int idx, ret; 321 int idx, ret;
300 322
323 if (!host_supports_tls)
324 return -ENOSYS;
325
301 if (get_user(idx, &user_desc->entry_number)) 326 if (get_user(idx, &user_desc->entry_number))
302 return -EFAULT; 327 return -EFAULT;
303 328
@@ -321,6 +346,9 @@ int ptrace_get_thread_area(struct task_struct *child, int idx,
321 struct user_desc info; 346 struct user_desc info;
322 int ret; 347 int ret;
323 348
349 if (!host_supports_tls)
350 return -EIO;
351
324 ret = get_tls_entry(child, &info, idx); 352 ret = get_tls_entry(child, &info, idx);
325 if (ret < 0) 353 if (ret < 0)
326 goto out; 354 goto out;
@@ -331,3 +359,26 @@ out:
331 return ret; 359 return ret;
332} 360}
333 361
362
363/* XXX: This part is probably common to i386 and x86-64. Don't create a common
364 * file for now, do that when implementing x86-64 support.*/
365static int __init __setup_host_supports_tls(void) {
366 check_host_supports_tls(&host_supports_tls, &host_gdt_entry_tls_min);
367 if (host_supports_tls) {
368 printk(KERN_INFO "Host TLS support detected\n");
369 printk(KERN_INFO "Detected host type: ");
370 switch (host_gdt_entry_tls_min) {
371 case GDT_ENTRY_TLS_MIN_I386:
372 printk("i386\n");
373 break;
374 case GDT_ENTRY_TLS_MIN_X86_64:
375 printk("x86_64\n");
376 break;
377 }
378 } else
379 printk(KERN_ERR " Host TLS support NOT detected! "
380 "TLS support inside UML will not work\n");
381 return 1;
382}
383
384__initcall(__setup_host_supports_tls);