[PATCH 3/3] MIPS: Remove get_fs/set_fs

From: Thomas Bogendoerfer
Date: Tue Mar 30 2021 - 13:27:45 EST

All get_fs/set_fs calls in MIPS code are gone, so remove implementation
of it. With the clear separation of user/kernel space access we no
longer need the EVA special handling, so get rid of that, too.

Signed-off-by: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
---
arch/mips/Kconfig | 1 -
arch/mips/include/asm/processor.h | 4 -
arch/mips/include/asm/thread_info.h | 6 -
arch/mips/include/asm/uaccess.h | 197 +++++++---------------------
arch/mips/kernel/asm-offsets.c | 1 -
arch/mips/kernel/process.c | 2 -
arch/mips/kernel/scall32-o32.S | 4 +-
arch/mips/lib/memset.S | 3 -
arch/mips/lib/strncpy_user.S | 48 ++-----
arch/mips/lib/strnlen_user.S | 44 ++-----
10 files changed, 75 insertions(+), 235 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index b72458215d20..70faa0686444 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -93,7 +93,6 @@ config MIPS
select PERF_USE_VMALLOC
select PCI_MSI_ARCH_FALLBACKS if PCI_MSI
select RTC_LIB
- select SET_FS
select SYSCTL_EXCEPTION_TRACE
select VIRT_TO_BUS
select ARCH_HAS_ELFCORE_COMPAT
diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h
index 8e69e0a35ee9..0c3550c82b72 100644
--- a/arch/mips/include/asm/processor.h
+++ b/arch/mips/include/asm/processor.h
@@ -221,10 +221,6 @@ struct nlm_cop2_state {
#define COP2_INIT
#endif

-typedef struct {
- unsigned long seg;
-} mm_segment_t;
-
#ifdef CONFIG_CPU_HAS_MSA
# define ARCH_MIN_TASKALIGN 16
# define FPU_ALIGN __aligned(16)
diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h
index e2c352da3877..0b17aaa9e012 100644
--- a/arch/mips/include/asm/thread_info.h
+++ b/arch/mips/include/asm/thread_info.h
@@ -28,11 +28,6 @@ struct thread_info {
unsigned long tp_value; /* thread pointer */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
- mm_segment_t addr_limit; /*
- * thread address space limit:
- * 0x7fffffff for user-thead
- * 0xffffffff for kernel-thread
- */
struct pt_regs *regs;
long syscall; /* syscall number */
};
@@ -46,7 +41,6 @@ struct thread_info {
.flags = _TIF_FIXADE, \
.cpu = 0, \
.preempt_count = INIT_PREEMPT_COUNT, \
- .addr_limit = KERNEL_DS, \
}

/*
diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
index 8b3a4b992ebc..5b1fd2e97f57 100644
--- a/arch/mips/include/asm/uaccess.h
+++ b/arch/mips/include/asm/uaccess.h
@@ -16,13 +16,6 @@
#include <asm/asm-eva.h>
#include <asm/extable.h>

-/*
- * The fs value determines whether argument validity checking should be
- * performed or not. If get_fs() == USER_DS, checking is performed, with
- * get_fs() == KERNEL_DS, checking is bypassed.
- *
- * For historical reasons, these macros are grossly misnamed.
- */
#ifdef CONFIG_32BIT

#define __UA_LIMIT 0x80000000UL
@@ -49,38 +42,6 @@ extern u64 __ua_limit;

#endif /* CONFIG_64BIT */

-/*
- * USER_DS is a bitmask that has the bits set that may not be set in a valid
- * userspace address. Note that we limit 32-bit userspace to 0x7fff8000 but
- * the arithmetic we're doing only works if the limit is a power of two, so
- * we use 0x80000000 here on 32-bit kernels. If a process passes an invalid
- * address in this range it's the process's problem, not ours :-)
- */
-
-#define KERNEL_DS ((mm_segment_t) { 0UL })
-#define USER_DS ((mm_segment_t) { __UA_LIMIT })
-
-#define get_fs() (current_thread_info()->addr_limit)
-#define set_fs(x) (current_thread_info()->addr_limit = (x))
-
-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-
-/*
- * eva_kernel_access() - determine whether kernel memory access on an EVA system
- *
- * Determines whether memory accesses should be performed to kernel memory
- * on a system using Extended Virtual Addressing (EVA).
- *
- * Return: true if a kernel memory access on an EVA system, else false.
- */
-static inline bool eva_kernel_access(void)
-{
- if (!IS_ENABLED(CONFIG_EVA))
- return false;
-
- return uaccess_kernel();
-}
-
/*
* Is a address valid? This does a straightforward calculation rather
* than tests.
@@ -118,7 +79,7 @@ static inline bool eva_kernel_access(void)
static inline int __access_ok(const void __user *p, unsigned long size)
{
unsigned long addr = (unsigned long)p;
- return (get_fs().seg & (addr | (addr + size) | __ua_size(size))) == 0;
+ return (__UA_LIMIT & (addr | (addr + size) | __ua_size(size))) == 0;
}

#define access_ok(addr, size) \
@@ -276,12 +237,9 @@ do { \
({ \
int __gu_err; \
\
- if (eva_kernel_access()) { \
- __get_kernel_common((x), size, ptr); \
- } else { \
- __chk_user_ptr(ptr); \
- __get_user_common((x), size, ptr); \
- } \
+ __chk_user_ptr(ptr); \
+ __get_user_common((x), size, ptr); \
+ \
__gu_err; \
})

@@ -291,11 +249,8 @@ do { \
const __typeof__(*(ptr)) __user * __gu_ptr = (ptr); \
\
might_fault(); \
- if (likely(access_ok( __gu_ptr, size))) { \
- if (eva_kernel_access()) \
- __get_kernel_common((x), size, __gu_ptr); \
- else \
- __get_user_common((x), size, __gu_ptr); \
+ if (likely(access_ok(__gu_ptr, size))) { \
+ __get_user_common((x), size, __gu_ptr); \
} else \
(x) = 0; \
\
@@ -452,12 +407,9 @@ do { \
int __pu_err = 0; \
\
__pu_val = (x); \
- if (eva_kernel_access()) { \
- __put_kernel_common(ptr, size); \
- } else { \
- __chk_user_ptr(ptr); \
- __put_user_common(ptr, size); \
- } \
+ __chk_user_ptr(ptr); \
+ __put_user_common(ptr, size); \
+ \
__pu_err; \
})

@@ -468,11 +420,8 @@ do { \
int __pu_err = -EFAULT; \
\
might_fault(); \
- if (likely(access_ok( __pu_addr, size))) { \
- if (eva_kernel_access()) \
- __put_kernel_common(__pu_addr, size); \
- else \
- __put_user_common(__pu_addr, size); \
+ if (likely(access_ok(__pu_addr, size))) { \
+ __put_user_common(__pu_addr, size); \
} \
\
__pu_err; \
@@ -595,15 +544,6 @@ extern size_t __copy_user(void *__to, const void *__from, size_t __n);
__cu_len_r; \
})

-#define __invoke_copy_from_kernel(to, from, n) \
- __invoke_copy_from(__copy_user, to, from, n)
-
-#define __invoke_copy_to_kernel(to, from, n) \
- __invoke_copy_to(__copy_user, to, from, n)
-
-#define ___invoke_copy_in_kernel(to, from, n) \
- __invoke_copy_from(__copy_user, to, from, n)
-
#ifndef CONFIG_EVA
#define __invoke_copy_from_user(to, from, n) \
__invoke_copy_from(__copy_user, to, from, n)
@@ -642,19 +582,13 @@ extern size_t __copy_in_user_eva(void *__to, const void *__from, size_t __n);
static inline unsigned long
raw_copy_to_user(void __user *to, const void *from, unsigned long n)
{
- if (eva_kernel_access())
- return __invoke_copy_to_kernel(to, from, n);
- else
- return __invoke_copy_to_user(to, from, n);
+ return __invoke_copy_to_user(to, from, n);
}

static inline unsigned long
raw_copy_from_user(void *to, const void __user *from, unsigned long n)
{
- if (eva_kernel_access())
- return __invoke_copy_from_kernel(to, from, n);
- else
- return __invoke_copy_from_user(to, from, n);
+ return __invoke_copy_from_user(to, from, n);
}

#define INLINE_COPY_FROM_USER
@@ -663,13 +597,9 @@ raw_copy_from_user(void *to, const void __user *from, unsigned long n)
static inline unsigned long
raw_copy_in_user(void __user*to, const void __user *from, unsigned long n)
{
- if (eva_kernel_access())
- return ___invoke_copy_in_kernel(to, from, n);
- else
- return ___invoke_copy_in_user(to, from, n);
+ return ___invoke_copy_in_user(to, from, n);
}

-extern __kernel_size_t __bzero_kernel(void __user *addr, __kernel_size_t size);
extern __kernel_size_t __bzero(void __user *addr, __kernel_size_t size);

/*
@@ -695,28 +625,16 @@ __clear_user(void __user *addr, __kernel_size_t size)
#define bzero_clobbers "$4", "$5", "$6", __UA_t0, __UA_t1, "$31"
#endif /* CONFIG_CPU_MICROMIPS */

- if (eva_kernel_access()) {
- __asm__ __volatile__(
- "move\t$4, %1\n\t"
- "move\t$5, $0\n\t"
- "move\t$6, %2\n\t"
- __MODULE_JAL(__bzero_kernel)
- "move\t%0, $6"
- : "=r" (res)
- : "r" (addr), "r" (size)
- : bzero_clobbers);
- } else {
- might_fault();
- __asm__ __volatile__(
- "move\t$4, %1\n\t"
- "move\t$5, $0\n\t"
- "move\t$6, %2\n\t"
- __MODULE_JAL(__bzero)
- "move\t%0, $6"
- : "=r" (res)
- : "r" (addr), "r" (size)
- : bzero_clobbers);
- }
+ might_fault();
+ __asm__ __volatile__(
+ "move\t$4, %1\n\t"
+ "move\t$5, $0\n\t"
+ "move\t$6, %2\n\t"
+ __MODULE_JAL(__bzero)
+ "move\t%0, $6"
+ : "=r" (res)
+ : "r" (addr), "r" (size)
+ : bzero_clobbers);

return res;
}
@@ -730,7 +648,6 @@ __clear_user(void __user *addr, __kernel_size_t size)
__cl_size; \
})

-extern long __strncpy_from_kernel_asm(char *__to, const char __user *__from, long __len);
extern long __strncpy_from_user_asm(char *__to, const char __user *__from, long __len);

/*
@@ -756,33 +673,23 @@ strncpy_from_user(char *__to, const char __user *__from, long __len)
{
long res;

- if (eva_kernel_access()) {
- __asm__ __volatile__(
- "move\t$4, %1\n\t"
- "move\t$5, %2\n\t"
- "move\t$6, %3\n\t"
- __MODULE_JAL(__strncpy_from_kernel_asm)
- "move\t%0, $2"
- : "=r" (res)
- : "r" (__to), "r" (__from), "r" (__len)
- : "$2", "$3", "$4", "$5", "$6", __UA_t0, "$31", "memory");
- } else {
- might_fault();
- __asm__ __volatile__(
- "move\t$4, %1\n\t"
- "move\t$5, %2\n\t"
- "move\t$6, %3\n\t"
- __MODULE_JAL(__strncpy_from_user_asm)
- "move\t%0, $2"
- : "=r" (res)
- : "r" (__to), "r" (__from), "r" (__len)
- : "$2", "$3", "$4", "$5", "$6", __UA_t0, "$31", "memory");
- }
+ if (!access_ok(__from, __len))
+ return -EFAULT;
+
+ might_fault();
+ __asm__ __volatile__(
+ "move\t$4, %1\n\t"
+ "move\t$5, %2\n\t"
+ "move\t$6, %3\n\t"
+ __MODULE_JAL(__strncpy_from_user_asm)
+ "move\t%0, $2"
+ : "=r" (res)
+ : "r" (__to), "r" (__from), "r" (__len)
+ : "$2", "$3", "$4", "$5", "$6", __UA_t0, "$31", "memory");

return res;
}

-extern long __strnlen_kernel_asm(const char __user *s, long n);
extern long __strnlen_user_asm(const char __user *s, long n);

/*
@@ -802,26 +709,18 @@ static inline long strnlen_user(const char __user *s, long n)
{
long res;

+ if (!access_ok(s, n))
+ return -0;
+
might_fault();
- if (eva_kernel_access()) {
- __asm__ __volatile__(
- "move\t$4, %1\n\t"
- "move\t$5, %2\n\t"
- __MODULE_JAL(__strnlen_kernel_asm)
- "move\t%0, $2"
- : "=r" (res)
- : "r" (s), "r" (n)
- : "$2", "$4", "$5", __UA_t0, "$31");
- } else {
- __asm__ __volatile__(
- "move\t$4, %1\n\t"
- "move\t$5, %2\n\t"
- __MODULE_JAL(__strnlen_user_asm)
- "move\t%0, $2"
- : "=r" (res)
- : "r" (s), "r" (n)
- : "$2", "$4", "$5", __UA_t0, "$31");
- }
+ __asm__ __volatile__(
+ "move\t$4, %1\n\t"
+ "move\t$5, %2\n\t"
+ __MODULE_JAL(__strnlen_user_asm)
+ "move\t%0, $2"
+ : "=r" (res)
+ : "r" (s), "r" (n)
+ : "$2", "$4", "$5", __UA_t0, "$31");

return res;
}
diff --git a/arch/mips/kernel/asm-offsets.c b/arch/mips/kernel/asm-offsets.c
index aebfda81120a..5735b2cd6f2a 100644
--- a/arch/mips/kernel/asm-offsets.c
+++ b/arch/mips/kernel/asm-offsets.c
@@ -98,7 +98,6 @@ void output_thread_info_defines(void)
OFFSET(TI_TP_VALUE, thread_info, tp_value);
OFFSET(TI_CPU, thread_info, cpu);
OFFSET(TI_PRE_COUNT, thread_info, preempt_count);
- OFFSET(TI_ADDR_LIMIT, thread_info, addr_limit);
OFFSET(TI_REGS, thread_info, regs);
DEFINE(_THREAD_SIZE, THREAD_SIZE);
DEFINE(_THREAD_MASK, THREAD_MASK);
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 7efa0d1a4c2b..bff080db0294 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -124,7 +124,6 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
/* kernel thread */
unsigned long status = p->thread.cp0_status;
memset(childregs, 0, sizeof(struct pt_regs));
- ti->addr_limit = KERNEL_DS;
p->thread.reg16 = usp; /* fn */
p->thread.reg17 = kthread_arg;
p->thread.reg29 = childksp;
@@ -145,7 +144,6 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
childregs->regs[2] = 0; /* Child gets zero as return value */
if (usp)
childregs->regs[29] = usp;
- ti->addr_limit = USER_DS;

p->thread.reg29 = (unsigned long) childregs;
p->thread.reg31 = (unsigned long) ret_from_fork;
diff --git a/arch/mips/kernel/scall32-o32.S b/arch/mips/kernel/scall32-o32.S
index 84e8624e83a2..b1b2e106f711 100644
--- a/arch/mips/kernel/scall32-o32.S
+++ b/arch/mips/kernel/scall32-o32.S
@@ -48,10 +48,8 @@ NESTED(handle_sys, PT_SIZE, sp)
* We intentionally keep the kernel stack a little below the top of
* userspace so we don't have to do a slower byte accurate check here.
*/
- lw t5, TI_ADDR_LIMIT($28)
addu t4, t0, 32
- and t5, t4
- bltz t5, bad_stack # -> sp is bad
+ bltz t4, bad_stack # -> sp is bad

/*
* Ok, copy the args from the luser stack to the kernel stack.
diff --git a/arch/mips/lib/memset.S b/arch/mips/lib/memset.S
index d5449e8a3dfc..b0baa3c79fad 100644
--- a/arch/mips/lib/memset.S
+++ b/arch/mips/lib/memset.S
@@ -314,9 +314,6 @@ EXPORT_SYMBOL(memset)
#ifndef CONFIG_EVA
FEXPORT(__bzero)
EXPORT_SYMBOL(__bzero)
-#else
-FEXPORT(__bzero_kernel)
-EXPORT_SYMBOL(__bzero_kernel)
#endif
__BUILD_BZERO LEGACY_MODE

diff --git a/arch/mips/lib/strncpy_user.S b/arch/mips/lib/strncpy_user.S
index acdff66bd5d2..556acf684d7b 100644
--- a/arch/mips/lib/strncpy_user.S
+++ b/arch/mips/lib/strncpy_user.S
@@ -29,19 +29,17 @@
* it happens at most some bytes of the exceptions handlers will be copied.
*/

- .macro __BUILD_STRNCPY_ASM func
-LEAF(__strncpy_from_\func\()_asm)
- LONG_L v0, TI_ADDR_LIMIT($28) # pointer ok?
- and v0, a1
- bnez v0, .Lfault\@
-
+LEAF(__strncpy_from_user_asm)
move t0, zero
move v1, a1
-.ifeqs "\func","kernel"
-1: EX(lbu, v0, (v1), .Lfault\@)
-.else
-1: EX(lbue, v0, (v1), .Lfault\@)
-.endif
+#ifdef CONFIG_EVA
+ .set push
+ .set eva
+1: EX(lbue, v0, (v1), .Lfault)
+ .set pop
+#else
+1: EX(lbu, v0, (v1), .Lfault)
+#endif
PTR_ADDIU v1, 1
R10KCBARRIER(0(ra))
sb v0, (a0)
@@ -51,35 +49,17 @@ LEAF(__strncpy_from_\func\()_asm)
bne t0, a2, 1b
2: PTR_ADDU v0, a1, t0
xor v0, a1
- bltz v0, .Lfault\@
+ bltz v0, .Lfault
move v0, t0
jr ra # return n
- END(__strncpy_from_\func\()_asm)
+ END(__strncpy_from_user_asm)

-.Lfault\@:
+.Lfault:
li v0, -EFAULT
jr ra

.section __ex_table,"a"
- PTR 1b, .Lfault\@
+ PTR 1b, .Lfault
.previous

- .endm
-
-#ifndef CONFIG_EVA
- /* Set aliases */
- .global __strncpy_from_user_asm
- .set __strncpy_from_user_asm, __strncpy_from_kernel_asm
-EXPORT_SYMBOL(__strncpy_from_user_asm)
-#endif
-
-__BUILD_STRNCPY_ASM kernel
-EXPORT_SYMBOL(__strncpy_from_kernel_asm)
-
-#ifdef CONFIG_EVA
- .set push
- .set eva
-__BUILD_STRNCPY_ASM user
- .set pop
-EXPORT_SYMBOL(__strncpy_from_user_asm)
-#endif
+ EXPORT_SYMBOL(__strncpy_from_user_asm)
diff --git a/arch/mips/lib/strnlen_user.S b/arch/mips/lib/strnlen_user.S
index e1bacf5a3abe..92b63f20ec05 100644
--- a/arch/mips/lib/strnlen_user.S
+++ b/arch/mips/lib/strnlen_user.S
@@ -26,12 +26,7 @@
* bytes. There's nothing secret there. On 64-bit accessing beyond
* the maximum is a tad hairier ...
*/
- .macro __BUILD_STRNLEN_ASM func
-LEAF(__strnlen_\func\()_asm)
- LONG_L v0, TI_ADDR_LIMIT($28) # pointer ok?
- and v0, a0
- bnez v0, .Lfault\@
-
+LEAF(__strnlen_user_asm)
move v0, a0
PTR_ADDU a1, a0 # stop pointer
1:
@@ -40,11 +35,14 @@ LEAF(__strnlen_\func\()_asm)
li AT, 1
#endif
beq v0, a1, 1f # limit reached?
-.ifeqs "\func", "kernel"
- EX(lb, t0, (v0), .Lfault\@)
-.else
- EX(lbe, t0, (v0), .Lfault\@)
-.endif
+#ifdef CONFIG_EVA
+ .set push
+ .set eva
+ EX(lbe, t0, (v0), .Lfault)
+ .set pop
+#else
+ EX(lb, t0, (v0), .Lfault)
+#endif
.set noreorder
bnez t0, 1b
1:
@@ -57,28 +55,10 @@ LEAF(__strnlen_\func\()_asm)
.set reorder
PTR_SUBU v0, a0
jr ra
- END(__strnlen_\func\()_asm)
+ END(__strnlen_user_asm)

-.Lfault\@:
+.Lfault:
move v0, zero
jr ra
- .endm
-
-#ifndef CONFIG_EVA
- /* Set aliases */
- .global __strnlen_user_asm
- .set __strnlen_user_asm, __strnlen_kernel_asm
-EXPORT_SYMBOL(__strnlen_user_asm)
-#endif
-
-__BUILD_STRNLEN_ASM kernel
-EXPORT_SYMBOL(__strnlen_kernel_asm)
-
-#ifdef CONFIG_EVA

- .set push
- .set eva
-__BUILD_STRNLEN_ASM user
- .set pop
-EXPORT_SYMBOL(__strnlen_user_asm)
-#endif
+ EXPORT_SYMBOL(__strnlen_user_asm)
--
2.29.2