Revision 61f01dd941ba9e06d2bf05994450ecc3d61b6b8b authored by Andy Lutomirski on 26 April 2015, 23:47:59 UTC, committed by Linus Torvalds on 27 April 2015, 00:57:38 UTC
AMD CPUs don't reinitialize the SS descriptor on SYSRET, so SYSRET with SS == 0 results in an invalid usermode state in which SS is apparently equal to __USER_DS but causes #SS if used. Work around the issue by setting SS to __KERNEL_DS __switch_to, thus ensuring that SYSRET never happens with SS set to NULL. This was exposed by a recent vDSO cleanup. Fixes: e7d6eefaaa44 x86/vdso32/syscall.S: Do not load __USER32_DS to %ss Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Peter Anvin <hpa@zytor.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Denys Vlasenko <vda.linux@googlemail.com> Cc: Brian Gerst <brgerst@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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head.S
;
; Port on Texas Instruments TMS320C6x architecture
;
; Copyright (C) 2004, 2009, 2010, 2011 Texas Instruments Incorporated
; Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License version 2 as
; published by the Free Software Foundation.
;
#include <linux/linkage.h>
#include <linux/of_fdt.h>
#include <asm/asm-offsets.h>
__HEAD
ENTRY(_c_int00)
;; Save magic and pointer
MV .S1 A4,A10
MV .S2 B4,B10
MVKL .S2 __bss_start,B5
MVKH .S2 __bss_start,B5
MVKL .S2 __bss_stop,B6
MVKH .S2 __bss_stop,B6
SUB .L2 B6,B5,B6 ; bss size
;; Set the stack pointer
MVKL .S2 current_ksp,B0
MVKH .S2 current_ksp,B0
LDW .D2T2 *B0,B15
;; clear bss
SHR .S2 B6,3,B0 ; number of dwords to clear
ZERO .L2 B13
ZERO .L2 B12
bss_loop:
BDEC .S2 bss_loop,B0
NOP 3
CMPLT .L2 B0,0,B1
[!B1] STDW .D2T2 B13:B12,*B5++[1]
NOP 4
AND .D2 ~7,B15,B15
;; Clear GIE and PGIE
MVC .S2 CSR,B2
CLR .S2 B2,0,1,B2
MVC .S2 B2,CSR
MVC .S2 TSR,B2
CLR .S2 B2,0,1,B2
MVC .S2 B2,TSR
MVC .S2 ITSR,B2
CLR .S2 B2,0,1,B2
MVC .S2 B2,ITSR
MVC .S2 NTSR,B2
CLR .S2 B2,0,1,B2
MVC .S2 B2,NTSR
;; pass DTB pointer to machine_init (or zero if none)
MVKL .S1 OF_DT_HEADER,A0
MVKH .S1 OF_DT_HEADER,A0
CMPEQ .L1 A10,A0,A0
[A0] MV .S1X B10,A4
[!A0] MVK .S1 0,A4
#ifdef CONFIG_C6X_BIG_KERNEL
MVKL .S1 machine_init,A0
MVKH .S1 machine_init,A0
B .S2X A0
ADDKPC .S2 0f,B3,4
0:
#else
CALLP .S2 machine_init,B3
#endif
;; Jump to Linux init
#ifdef CONFIG_C6X_BIG_KERNEL
MVKL .S1 start_kernel,A0
MVKH .S1 start_kernel,A0
B .S2X A0
#else
B .S2 start_kernel
#endif
NOP 5
L1: BNOP .S2 L1,5
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