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: Anton Vorontsov <cbouatmailru@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index 062b58c..4e84d09c 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -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
diff --git a/arch/arm/include/asm/domain.h b/arch/arm/include/asm/domain.h
index cc7ef40..af18cea 100644
--- a/arch/arm/include/asm/domain.h
+++ b/arch/arm/include/asm/domain.h
@@ -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 */
diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h
index 540a044..b33fe70 100644
--- a/arch/arm/include/asm/futex.h
+++ b/arch/arm/include/asm/futex.h
@@ -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 @@
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"
diff --git a/arch/arm/include/asm/traps.h b/arch/arm/include/asm/traps.h
index 491960b..af5d5d1 100644
--- a/arch/arm/include/asm/traps.h
+++ b/arch/arm/include/asm/traps.h
@@ -27,4 +27,6 @@
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
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index 33e4a48..b293616 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -227,7 +227,7 @@
#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 @@
#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 @@
#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 @@
#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 @@
#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" \
