linux-kernel - Re: [PATCH v3 4/4] selftests/x86: Add tests for UC_SIGCONTEXT_SS and UC_STRICT_RESTORE

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Date:	Thu, 11 Feb 2016 16:46:31 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Andy Lutomirski <luto@...nel.org>, X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Brian Gerst <brgerst@...il.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Stas Sergeev <stsp@...t.ru>,
	Cyrill Gorcunov <gorcunov@...il.com>,
	Pavel Emelyanov <xemul@...allels.com>
Subject: Re: [PATCH v3 4/4] selftests/x86: Add tests for UC_SIGCONTEXT_SS and UC_STRICT_RESTORE_SS

On Thu, Feb 11, 2016 at 11:53 AM, Borislav Petkov <bp@...en8.de> wrote:
> On Mon, Jan 25, 2016 at 01:34:15PM -0800, Andy Lutomirski wrote:
>> This tests the two ABI-preserving cases that DOSEMU cares about, and
>> it also explicitly tests the new UC_SIGCONTEXT_SS and
>> UC_STRICT_RESTORE_SS flags.
>>
>> Signed-off-by: Andy Lutomirski <luto@...nel.org>
>> ---
>>  tools/testing/selftests/x86/sigreturn.c | 240 ++++++++++++++++++++++++++++----
>>  1 file changed, 212 insertions(+), 28 deletions(-)
>>
>> diff --git a/tools/testing/selftests/x86/sigreturn.c b/tools/testing/selftests/x86/sigreturn.c
>> index b5aa1bab7416..43e840470e32 100644
>> --- a/tools/testing/selftests/x86/sigreturn.c
>> +++ b/tools/testing/selftests/x86/sigreturn.c
>> @@ -55,6 +55,47 @@
>>  #include <sys/user.h>
>>
>>  /*
>> + * Copied from asm/ucontext.h, as asm/ucontext.h conflicts badly with the glibc
>> + * headers.
>> + */
>> +#ifdef __x86_64__
>> +/*
>> + * UC_SAVED_SS will be set when delivering 64-bit or x32 signals on
>> + * kernels that save SS in the sigcontext.  Kernels that set UC_SAVED_SS
>> + * allow signal handlers to set UC_RESTORE_SS; if UC_RESTORE_SS is set,
>> + * then sigreturn will restore SS.
>> + *
>> + * For compatibility with old programs, the kernel will *not* set
>> + * UC_RESTORE_SS when delivering signals.
>
> Those UC_SAVED_SS and UC_RESTORE_SS look stale to me.

Indeed.

>
>> + */
>> +#define UC_SIGCONTEXT_SS       0x2
>> +#define UC_STRICT_RESTORE_SS   0x4
>> +#endif
>> +
>> +/* Access rights as returned by LAR */
>> +#define AR_TYPE_RODATA               (0 * (1 << 9))
>> +#define AR_TYPE_RWDATA               (1 * (1 << 9))
>> +#define AR_TYPE_RODATA_EXPDOWN       (2 * (1 << 9))
>> +#define AR_TYPE_RWDATA_EXPDOWN       (3 * (1 << 9))
>> +#define AR_TYPE_XOCODE               (4 * (1 << 9))
>> +#define AR_TYPE_XRCODE               (5 * (1 << 9))
>> +#define AR_TYPE_XOCODE_CONF  (6 * (1 << 9))
>> +#define AR_TYPE_XRCODE_CONF  (7 * (1 << 9))
>> +#define AR_TYPE_MASK         (7 * (1 << 9))
>> +
>> +#define AR_DPL0                      (0 * (1 << 13))
>> +#define AR_DPL3                      (3 * (1 << 13))
>> +#define AR_DPL_MASK          (3 * (1 << 13))
>> +
>> +#define AR_A                 (1 << 8)        /* A means "accessed" */
>> +#define AR_S                 (1 << 12)       /* S means "not system" */
>> +#define AR_P                 (1 << 15)       /* P means "present" */
>> +#define AR_AVL                       (1 << 20)       /* AVL does nothing */
>> +#define AR_L                 (1 << 21)       /* L means "long mode" */
>> +#define AR_DB                        (1 << 22)       /* D or B, depending on type */
>> +#define AR_G                 (1 << 23)       /* G means "limit in pages" */
>
> Why not include the kernel header instead of repeating it here again?
>

Too tangled.  Adding:

#include "../../../../arch/x86/include/asm/desc_defs.h"

Complains that u16 isn't a type.  Trying to include types.h doesn't
work well either.

--Andy