lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

[PATCH] uml: check for differences in host support

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

55
arch/um/sys-i386/tls.c
View File

@ -24,6 +24,10 @@
#include "skas.h"
#endif
/* If needed we can detect when it's uninitialized. */
static int host_supports_tls = -1;
int host_gdt_entry_tls_min = -1;
#ifdef CONFIG_MODE_SKAS
int do_set_thread_area_skas(struct user_desc *info)
{
@ -157,11 +161,20 @@ void clear_flushed_tls(struct task_struct *task)
}
}
/* This in SKAS0 does not need to be used, since we have different host
* processes. Nor will this need to be used when we'll add support to the host
/* In SKAS0 mode, currently, multiple guest threads sharing the same ->mm have a
* common host process. So this is needed in SKAS0 too.
*
* However, if each thread had a different host process (and this was discussed
* for SMP support) this won't be needed.
*
* And this will not need be used when (and if) we'll add support to the host
* SKAS patch. */
int arch_switch_tls_skas(struct task_struct *from, struct task_struct *to)
{
if (!host_supports_tls)
return 0;
/* We have no need whatsoever to switch TLS for kernel threads; beyond
* that, that would also result in us calling os_set_thread_area with
* 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)
int arch_switch_tls_tt(struct task_struct *from, struct task_struct *to)
{
if (!host_supports_tls)
return 0;
if (needs_TLS_update(to))
return load_TLS(0, to);
@ -256,6 +272,9 @@ asmlinkage int sys_set_thread_area(struct user_desc __user *user_desc)
struct user_desc info;
int idx, ret;
if (!host_supports_tls)
return -ENOSYS;
if (copy_from_user(&info, user_desc, sizeof(info)))
return -EFAULT;
@ -287,6 +306,9 @@ int ptrace_set_thread_area(struct task_struct *child, int idx,
{
struct user_desc info;
if (!host_supports_tls)
return -EIO;
if (copy_from_user(&info, user_desc, sizeof(info)))
return -EFAULT;
@ -298,6 +320,9 @@ asmlinkage int sys_get_thread_area(struct user_desc __user *user_desc)
struct user_desc info;
int idx, ret;
if (!host_supports_tls)
return -ENOSYS;
if (get_user(idx, &user_desc->entry_number))
return -EFAULT;
@ -321,6 +346,9 @@ int ptrace_get_thread_area(struct task_struct *child, int idx,
struct user_desc info;
int ret;
if (!host_supports_tls)
return -EIO;
ret = get_tls_entry(child, &info, idx);
if (ret < 0)
goto out;
@ -331,3 +359,26 @@ out:
return ret;
}
/* XXX: This part is probably common to i386 and x86-64. Don't create a common
* file for now, do that when implementing x86-64 support.*/
static int __init __setup_host_supports_tls(void) {
check_host_supports_tls(&host_supports_tls, &host_gdt_entry_tls_min);
if (host_supports_tls) {
printk(KERN_INFO "Host TLS support detected\n");
printk(KERN_INFO "Detected host type: ");
switch (host_gdt_entry_tls_min) {
case GDT_ENTRY_TLS_MIN_I386:
printk("i386\n");
break;
case GDT_ENTRY_TLS_MIN_X86_64:
printk("x86_64\n");
break;
}
} else
printk(KERN_ERR " Host TLS support NOT detected! "
"TLS support inside UML will not work\n");
return 1;
}
__initcall(__setup_host_supports_tls);