Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 247055aa authored by Catalin Marinas's avatar Catalin Marinas Committed by Russell King
Browse files

ARM: 6384/1: Remove the domain switching on ARMv6k/v7 CPUs 



This patch removes the domain switching functionality via the set_fs and
__switch_to functions on cores that have a TLS register.

Currently, the ioremap and vmalloc areas share the same level 1 page
tables and therefore have the same domain (DOMAIN_KERNEL). When the
kernel domain is modified from Client to Manager (via the __set_fs or in
the __switch_to function), the XN (eXecute Never) bit is overridden and
newer CPUs can speculatively prefetch the ioremap'ed memory.

Linux performs the kernel domain switching to allow user-specific
functions (copy_to/from_user, get/put_user etc.) to access kernel
memory. In order for these functions to work with the kernel domain set
to Client, the patch modifies the LDRT/STRT and related instructions to
the LDR/STR ones.

The user pages access rights are also modified for kernel read-only
access rather than read/write so that the copy-on-write mechanism still
works. CPU_USE_DOMAINS gets disabled only if the hardware has a TLS register
(CPU_32v6K is defined) since writing the TLS value to the high vectors page
isn't possible.

The user addresses passed to the kernel are checked by the access_ok()
function so that they do not point to the kernel space.

Tested-by: default avatarAnton Vorontsov <cbouatmailru@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent ff8b16d7

arch/arm/include/asm/assembler.h

+7 −6
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#endif



#include <asm/ptrace.h>

#include <asm/domain.h>



/*

 * Endian independent macros for shifting bytes within registers.
@@ -206,12 +207,12 @@ 
 */

#ifdef CONFIG_THUMB2_KERNEL



	.macro	usraccoff, instr, reg, ptr, inc, off, cond, abort

	.macro	usraccoff, instr, reg, ptr, inc, off, cond, abort, t=T()

9999:

	.if	\inc == 1

	\instr\cond\()bt \reg, [\ptr, #\off]

	\instr\cond\()b\()\t\().w \reg, [\ptr, #\off]

	.elseif	\inc == 4

	\instr\cond\()t \reg, [\ptr, #\off]

	\instr\cond\()\t\().w \reg, [\ptr, #\off]

	.else

	.error	"Unsupported inc macro argument"

	.endif
@@ -246,13 +247,13 @@ 


#else	/* !CONFIG_THUMB2_KERNEL */



	.macro	usracc, instr, reg, ptr, inc, cond, rept, abort

	.macro	usracc, instr, reg, ptr, inc, cond, rept, abort, t=T()

	.rept	\rept

9999:

	.if	\inc == 1

	\instr\cond\()bt \reg, [\ptr], #\inc

	\instr\cond\()b\()\t \reg, [\ptr], #\inc

	.elseif	\inc == 4

	\instr\cond\()t \reg, [\ptr], #\inc

	\instr\cond\()\t \reg, [\ptr], #\inc

	.else

	.error	"Unsupported inc macro argument"

	.endif

arch/arm/include/asm/domain.h

+29 −2
Original line number Diff line number Diff line
@@ -45,13 +45,17 @@ 
 */

#define DOMAIN_NOACCESS	0

#define DOMAIN_CLIENT	1

#ifdef CONFIG_CPU_USE_DOMAINS

#define DOMAIN_MANAGER	3

#else

#define DOMAIN_MANAGER	1

#endif



#define domain_val(dom,type)	((type) << (2*(dom)))



#ifndef __ASSEMBLY__



#ifdef CONFIG_MMU

#ifdef CONFIG_CPU_USE_DOMAINS

#define set_domain(x)					\

	do {						\

	__asm__ __volatile__(				\
@@ -74,5 +78,28 @@ 
#define modify_domain(dom,type)	do { } while (0)

#endif



/*

 * Generate the T (user) versions of the LDR/STR and related

 * instructions (inline assembly)

 */

#ifdef CONFIG_CPU_USE_DOMAINS

#define T(instr)	#instr "t"

#else

#define T(instr)	#instr

#endif

#endif /* !__ASSEMBLY__ */
 


#else /* __ASSEMBLY__ */



/*

 * Generate the T (user) versions of the LDR/STR and related

 * instructions

 */

#ifdef CONFIG_CPU_USE_DOMAINS

#define T(instr)	instr ## t

#else

#define T(instr)	instr

#endif



#endif /* __ASSEMBLY__ */



#endif /* !__ASM_PROC_DOMAIN_H */

arch/arm/include/asm/futex.h

+5 −4
Original line number Diff line number Diff line
@@ -13,12 +13,13 @@ 
#include <linux/preempt.h>

#include <linux/uaccess.h>

#include <asm/errno.h>

#include <asm/domain.h>



#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)	\

	__asm__ __volatile__(					\

	"1:	ldrt	%1, [%2]\n"				\

	"1:	" T(ldr) "	%1, [%2]\n"			\

	"	" insn "\n"					\

	"2:	strt	%0, [%2]\n"				\

	"2:	" T(str) "	%0, [%2]\n"			\

	"	mov	%0, #0\n"				\

	"3:\n"							\

	"	.pushsection __ex_table,\"a\"\n"		\
@@ -97,10 +98,10 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) 
	pagefault_disable();	/* implies preempt_disable() */



	__asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"

	"1:	ldrt	%0, [%3]\n"

	"1:	" T(ldr) "	%0, [%3]\n"

	"	teq	%0, %1\n"

	"	it	eq	@ explicit IT needed for the 2b label\n"

	"2:	streqt	%2, [%3]\n"

	"2:	" T(streq) "	%2, [%3]\n"

	"3:\n"

	"	.pushsection __ex_table,\"a\"\n"

	"	.align	3\n"

arch/arm/include/asm/traps.h

+2 −0
Original line number Diff line number Diff line
@@ -27,4 +27,6 @@ static inline int in_exception_text(unsigned long ptr) 
extern void __init early_trap_init(void);

extern void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame);



extern void *vectors_page;



#endif

arch/arm/include/asm/uaccess.h

+8 −8
Original line number Diff line number Diff line
@@ -227,7 +227,7 @@ do { \ 


#define __get_user_asm_byte(x,addr,err)				\

	__asm__ __volatile__(					\

	"1:	ldrbt	%1,[%2]\n"				\

	"1:	" T(ldrb) "	%1,[%2],#0\n"			\

	"2:\n"							\

	"	.pushsection .fixup,\"ax\"\n"			\

	"	.align	2\n"					\
@@ -263,7 +263,7 @@ do { \ 


#define __get_user_asm_word(x,addr,err)				\

	__asm__ __volatile__(					\

	"1:	ldrt	%1,[%2]\n"				\

	"1:	" T(ldr) "	%1,[%2],#0\n"			\

	"2:\n"							\

	"	.pushsection .fixup,\"ax\"\n"			\

	"	.align	2\n"					\
@@ -308,7 +308,7 @@ do { \ 


#define __put_user_asm_byte(x,__pu_addr,err)			\

	__asm__ __volatile__(					\

	"1:	strbt	%1,[%2]\n"				\

	"1:	" T(strb) "	%1,[%2],#0\n"			\

	"2:\n"							\

	"	.pushsection .fixup,\"ax\"\n"			\

	"	.align	2\n"					\
@@ -341,7 +341,7 @@ do { \ 


#define __put_user_asm_word(x,__pu_addr,err)			\

	__asm__ __volatile__(					\

	"1:	strt	%1,[%2]\n"				\

	"1:	" T(str) "	%1,[%2],#0\n"			\

	"2:\n"							\

	"	.pushsection .fixup,\"ax\"\n"			\

	"	.align	2\n"					\
@@ -366,10 +366,10 @@ do { \ 


#define __put_user_asm_dword(x,__pu_addr,err)			\

	__asm__ __volatile__(					\

 ARM(	"1:	strt	" __reg_oper1 ", [%1], #4\n"	)	\

 ARM(	"2:	strt	" __reg_oper0 ", [%1]\n"	)	\

 THUMB(	"1:	strt	" __reg_oper1 ", [%1]\n"	)	\

 THUMB(	"2:	strt	" __reg_oper0 ", [%1, #4]\n"	)	\

 ARM(	"1:	" T(str) "	" __reg_oper1 ", [%1], #4\n"	)	\

 ARM(	"2:	" T(str) "	" __reg_oper0 ", [%1]\n"	)	\

 THUMB(	"1:	" T(str) "	" __reg_oper1 ", [%1]\n"	)	\

 THUMB(	"2:	" T(str) "	" __reg_oper0 ", [%1, #4]\n"	)	\

	"3:\n"							\

	"	.pushsection .fixup,\"ax\"\n"			\

	"	.align	2\n"					\