diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/um/include/os.h | 1 | ||||
| -rw-r--r-- | arch/um/include/sysdep-i386/tls.h | 4 | ||||
| -rw-r--r-- | arch/um/include/user_util.h | 3 | ||||
| -rw-r--r-- | arch/um/os-Linux/sys-i386/Makefile | 2 | ||||
| -rw-r--r-- | arch/um/os-Linux/sys-i386/tls.c | 33 | ||||
| -rw-r--r-- | arch/um/os-Linux/tls.c | 4 | ||||
| -rw-r--r-- | arch/um/sys-i386/tls.c | 55 |
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); extern void os_early_checks(void); extern int can_do_skas(void); extern void os_check_bugs(void); +extern void check_host_supports_tls(int *supports_tls, int *tls_min); /* Make sure they are clear when running in TT mode. Required by * 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 { typedef struct user_desc user_desc_t; # endif /* __KERNEL__ */ + +#define GDT_ENTRY_TLS_MIN_I386 6 +#define GDT_ENTRY_TLS_MIN_X86_64 12 + #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 @@ #include "sysdep/ptrace.h" +/* Copied from kernel.h */ +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) + #define CATCH_EINTR(expr) while ((errno = 0, ((expr) < 0)) && (errno == EINTR)) extern 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 @@ # Licensed under the GPL # -obj-$(CONFIG_MODE_SKAS) = registers.o +obj-$(CONFIG_MODE_SKAS) = registers.o tls.o USER_OBJS := $(obj-y) 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 @@ +#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; +} 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) #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) { 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 @@ #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); |