Commit 3feb8856 authored by Paolo 'Blaisorblade' Giarrusso's avatar Paolo 'Blaisorblade' Giarrusso Committed by Linus Torvalds
Browse files

[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: default avatarPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: default avatarJeff Dike <jdike@addtoit.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 54d8d3b5

arch/um/include/os.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

arch/um/include/sysdep-i386/tls.h

+4 −0
Original line number Diff line number Diff line
@@ -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 */

arch/um/include/user_util.h

+3 −0
Original line number Diff line number Diff line
@@ -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;

arch/um/os-Linux/sys-i386/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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)

arch/um/os-Linux/sys-i386/tls.c

0 → 100644
+33 −0
Original line number Diff line number Diff line 
#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;

}

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