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-rw-r--r--arch/x86/entry/entry_32.S2
-rw-r--r--arch/x86/ia32/ia32_signal.c29
-rw-r--r--arch/x86/include/asm/alternative-asm.h11
-rw-r--r--arch/x86/include/asm/alternative.h10
-rw-r--r--arch/x86/include/asm/asm.h24
-rw-r--r--arch/x86/include/asm/nospec-branch.h28
-rw-r--r--arch/x86/include/asm/smap.h37
-rw-r--r--arch/x86/include/asm/switch_to.h1
-rw-r--r--arch/x86/include/asm/uaccess.h12
-rw-r--r--arch/x86/include/asm/uaccess_64.h3
-rw-r--r--arch/x86/include/asm/xen/hypercall.h24
-rw-r--r--arch/x86/kernel/process_32.c7
-rw-r--r--arch/x86/kernel/process_64.c1
-rw-r--r--arch/x86/kernel/signal.c29
-rw-r--r--arch/x86/lib/copy_user_64.S48
-rw-r--r--arch/x86/lib/memcpy_64.S3
-rw-r--r--arch/x86/lib/usercopy_64.c20
17 files changed, 181 insertions, 108 deletions
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index d309f30cf7af..5fc76b755510 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -650,6 +650,7 @@ ENTRY(__switch_to_asm)
pushl %ebx
pushl %edi
pushl %esi
+ pushfl
/* switch stack */
movl %esp, TASK_threadsp(%eax)
@@ -672,6 +673,7 @@ ENTRY(__switch_to_asm)
#endif
/* restore callee-saved registers */
+ popfl
popl %esi
popl %edi
popl %ebx
diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index 321fe5f5d0e9..4d5fcd47ab75 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -61,9 +61,8 @@
} while (0)
#define RELOAD_SEG(seg) { \
- unsigned int pre = GET_SEG(seg); \
+ unsigned int pre = (seg) | 3; \
unsigned int cur = get_user_seg(seg); \
- pre |= 3; \
if (pre != cur) \
set_user_seg(seg, pre); \
}
@@ -72,6 +71,7 @@ static int ia32_restore_sigcontext(struct pt_regs *regs,
struct sigcontext_32 __user *sc)
{
unsigned int tmpflags, err = 0;
+ u16 gs, fs, es, ds;
void __user *buf;
u32 tmp;
@@ -79,16 +79,10 @@ static int ia32_restore_sigcontext(struct pt_regs *regs,
current->restart_block.fn = do_no_restart_syscall;
get_user_try {
- /*
- * Reload fs and gs if they have changed in the signal
- * handler. This does not handle long fs/gs base changes in
- * the handler, but does not clobber them at least in the
- * normal case.
- */
- RELOAD_SEG(gs);
- RELOAD_SEG(fs);
- RELOAD_SEG(ds);
- RELOAD_SEG(es);
+ gs = GET_SEG(gs);
+ fs = GET_SEG(fs);
+ ds = GET_SEG(ds);
+ es = GET_SEG(es);
COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
COPY(dx); COPY(cx); COPY(ip); COPY(ax);
@@ -106,6 +100,17 @@ static int ia32_restore_sigcontext(struct pt_regs *regs,
buf = compat_ptr(tmp);
} get_user_catch(err);
+ /*
+ * Reload fs and gs if they have changed in the signal
+ * handler. This does not handle long fs/gs base changes in
+ * the handler, but does not clobber them at least in the
+ * normal case.
+ */
+ RELOAD_SEG(gs);
+ RELOAD_SEG(fs);
+ RELOAD_SEG(ds);
+ RELOAD_SEG(es);
+
err |= fpu__restore_sig(buf, 1);
force_iret();
diff --git a/arch/x86/include/asm/alternative-asm.h b/arch/x86/include/asm/alternative-asm.h
index 31b627b43a8e..464034db299f 100644
--- a/arch/x86/include/asm/alternative-asm.h
+++ b/arch/x86/include/asm/alternative-asm.h
@@ -20,6 +20,17 @@
#endif
/*
+ * objtool annotation to ignore the alternatives and only consider the original
+ * instruction(s).
+ */
+.macro ANNOTATE_IGNORE_ALTERNATIVE
+ .Lannotate_\@:
+ .pushsection .discard.ignore_alts
+ .long .Lannotate_\@ - .
+ .popsection
+.endm
+
+/*
* Issue one struct alt_instr descriptor entry (need to put it into
* the section .altinstructions, see below). This entry contains
* enough information for the alternatives patching code to patch an
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 4c74073a19cc..094fbc9c0b1c 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -45,6 +45,16 @@
#define LOCK_PREFIX ""
#endif
+/*
+ * objtool annotation to ignore the alternatives and only consider the original
+ * instruction(s).
+ */
+#define ANNOTATE_IGNORE_ALTERNATIVE \
+ "999:\n\t" \
+ ".pushsection .discard.ignore_alts\n\t" \
+ ".long 999b - .\n\t" \
+ ".popsection\n\t"
+
struct alt_instr {
s32 instr_offset; /* original instruction */
s32 repl_offset; /* offset to replacement instruction */
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 6467757bb39f..3ff577c0b102 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -148,30 +148,6 @@
_ASM_PTR (entry); \
.popsection
-.macro ALIGN_DESTINATION
- /* check for bad alignment of destination */
- movl %edi,%ecx
- andl $7,%ecx
- jz 102f /* already aligned */
- subl $8,%ecx
- negl %ecx
- subl %ecx,%edx
-100: movb (%rsi),%al
-101: movb %al,(%rdi)
- incq %rsi
- incq %rdi
- decl %ecx
- jnz 100b
-102:
- .section .fixup,"ax"
-103: addl %ecx,%edx /* ecx is zerorest also */
- jmp copy_user_handle_tail
- .previous
-
- _ASM_EXTABLE_UA(100b, 103b)
- _ASM_EXTABLE_UA(101b, 103b)
- .endm
-
#else
# define _EXPAND_EXTABLE_HANDLE(x) #x
# define _ASM_EXTABLE_HANDLE(from, to, handler) \
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index dad12b767ba0..daf25b60c9e3 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -11,6 +11,15 @@
#include <asm/msr-index.h>
/*
+ * This should be used immediately before a retpoline alternative. It tells
+ * objtool where the retpolines are so that it can make sense of the control
+ * flow by just reading the original instruction(s) and ignoring the
+ * alternatives.
+ */
+#define ANNOTATE_NOSPEC_ALTERNATIVE \
+ ANNOTATE_IGNORE_ALTERNATIVE
+
+/*
* Fill the CPU return stack buffer.
*
* Each entry in the RSB, if used for a speculative 'ret', contains an
@@ -57,19 +66,6 @@
#ifdef __ASSEMBLY__
/*
- * This should be used immediately before a retpoline alternative. It tells
- * objtool where the retpolines are so that it can make sense of the control
- * flow by just reading the original instruction(s) and ignoring the
- * alternatives.
- */
-.macro ANNOTATE_NOSPEC_ALTERNATIVE
- .Lannotate_\@:
- .pushsection .discard.nospec
- .long .Lannotate_\@ - .
- .popsection
-.endm
-
-/*
* This should be used immediately before an indirect jump/call. It tells
* objtool the subsequent indirect jump/call is vouched safe for retpoline
* builds.
@@ -152,12 +148,6 @@
#else /* __ASSEMBLY__ */
-#define ANNOTATE_NOSPEC_ALTERNATIVE \
- "999:\n\t" \
- ".pushsection .discard.nospec\n\t" \
- ".long 999b - .\n\t" \
- ".popsection\n\t"
-
#define ANNOTATE_RETPOLINE_SAFE \
"999:\n\t" \
".pushsection .discard.retpoline_safe\n\t" \
diff --git a/arch/x86/include/asm/smap.h b/arch/x86/include/asm/smap.h
index db333300bd4b..f94a7d0ddd49 100644
--- a/arch/x86/include/asm/smap.h
+++ b/arch/x86/include/asm/smap.h
@@ -13,13 +13,12 @@
#ifndef _ASM_X86_SMAP_H
#define _ASM_X86_SMAP_H
-#include <linux/stringify.h>
#include <asm/nops.h>
#include <asm/cpufeatures.h>
/* "Raw" instruction opcodes */
-#define __ASM_CLAC .byte 0x0f,0x01,0xca
-#define __ASM_STAC .byte 0x0f,0x01,0xcb
+#define __ASM_CLAC ".byte 0x0f,0x01,0xca"
+#define __ASM_STAC ".byte 0x0f,0x01,0xcb"
#ifdef __ASSEMBLY__
@@ -28,10 +27,10 @@
#ifdef CONFIG_X86_SMAP
#define ASM_CLAC \
- ALTERNATIVE "", __stringify(__ASM_CLAC), X86_FEATURE_SMAP
+ ALTERNATIVE "", __ASM_CLAC, X86_FEATURE_SMAP
#define ASM_STAC \
- ALTERNATIVE "", __stringify(__ASM_STAC), X86_FEATURE_SMAP
+ ALTERNATIVE "", __ASM_STAC, X86_FEATURE_SMAP
#else /* CONFIG_X86_SMAP */
@@ -49,26 +48,46 @@
static __always_inline void clac(void)
{
/* Note: a barrier is implicit in alternative() */
- alternative("", __stringify(__ASM_CLAC), X86_FEATURE_SMAP);
+ alternative("", __ASM_CLAC, X86_FEATURE_SMAP);
}
static __always_inline void stac(void)
{
/* Note: a barrier is implicit in alternative() */
- alternative("", __stringify(__ASM_STAC), X86_FEATURE_SMAP);
+ alternative("", __ASM_STAC, X86_FEATURE_SMAP);
+}
+
+static __always_inline unsigned long smap_save(void)
+{
+ unsigned long flags;
+
+ asm volatile (ALTERNATIVE("", "pushf; pop %0; " __ASM_CLAC,
+ X86_FEATURE_SMAP)
+ : "=rm" (flags) : : "memory", "cc");
+
+ return flags;
+}
+
+static __always_inline void smap_restore(unsigned long flags)
+{
+ asm volatile (ALTERNATIVE("", "push %0; popf", X86_FEATURE_SMAP)
+ : : "g" (flags) : "memory", "cc");
}
/* These macros can be used in asm() statements */
#define ASM_CLAC \
- ALTERNATIVE("", __stringify(__ASM_CLAC), X86_FEATURE_SMAP)
+ ALTERNATIVE("", __ASM_CLAC, X86_FEATURE_SMAP)
#define ASM_STAC \
- ALTERNATIVE("", __stringify(__ASM_STAC), X86_FEATURE_SMAP)
+ ALTERNATIVE("", __ASM_STAC, X86_FEATURE_SMAP)
#else /* CONFIG_X86_SMAP */
static inline void clac(void) { }
static inline void stac(void) { }
+static inline unsigned long smap_save(void) { return 0; }
+static inline void smap_restore(unsigned long flags) { }
+
#define ASM_CLAC
#define ASM_STAC
diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h
index 7cf1a270d891..18a4b6890fa8 100644
--- a/arch/x86/include/asm/switch_to.h
+++ b/arch/x86/include/asm/switch_to.h
@@ -46,6 +46,7 @@ struct inactive_task_frame {
unsigned long r13;
unsigned long r12;
#else
+ unsigned long flags;
unsigned long si;
unsigned long di;
#endif
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 1954dd5552a2..bb21913885a3 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -427,10 +427,11 @@ do { \
({ \
__label__ __pu_label; \
int __pu_err = -EFAULT; \
- __typeof__(*(ptr)) __pu_val; \
- __pu_val = x; \
+ __typeof__(*(ptr)) __pu_val = (x); \
+ __typeof__(ptr) __pu_ptr = (ptr); \
+ __typeof__(size) __pu_size = (size); \
__uaccess_begin(); \
- __put_user_size(__pu_val, (ptr), (size), __pu_label); \
+ __put_user_size(__pu_val, __pu_ptr, __pu_size, __pu_label); \
__pu_err = 0; \
__pu_label: \
__uaccess_end(); \
@@ -705,7 +706,7 @@ extern struct movsl_mask {
* checking before using them, but you have to surround them with the
* user_access_begin/end() pair.
*/
-static __must_check inline bool user_access_begin(const void __user *ptr, size_t len)
+static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len)
{
if (unlikely(!access_ok(ptr,len)))
return 0;
@@ -715,6 +716,9 @@ static __must_check inline bool user_access_begin(const void __user *ptr, size_t
#define user_access_begin(a,b) user_access_begin(a,b)
#define user_access_end() __uaccess_end()
+#define user_access_save() smap_save()
+#define user_access_restore(x) smap_restore(x)
+
#define unsafe_put_user(x, ptr, label) \
__put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label)
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index a9d637bc301d..5cd1caa8bc65 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -208,9 +208,6 @@ __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size)
}
unsigned long
-copy_user_handle_tail(char *to, char *from, unsigned len);
-
-unsigned long
mcsafe_handle_tail(char *to, char *from, unsigned len);
#endif /* _ASM_X86_UACCESS_64_H */
diff --git a/arch/x86/include/asm/xen/hypercall.h b/arch/x86/include/asm/xen/hypercall.h
index 2863c2026655..d50c7b747d8b 100644
--- a/arch/x86/include/asm/xen/hypercall.h
+++ b/arch/x86/include/asm/xen/hypercall.h
@@ -217,6 +217,22 @@ xen_single_call(unsigned int call,
return (long)__res;
}
+static __always_inline void __xen_stac(void)
+{
+ /*
+ * Suppress objtool seeing the STAC/CLAC and getting confused about it
+ * calling random code with AC=1.
+ */
+ asm volatile(ANNOTATE_IGNORE_ALTERNATIVE
+ ASM_STAC ::: "memory", "flags");
+}
+
+static __always_inline void __xen_clac(void)
+{
+ asm volatile(ANNOTATE_IGNORE_ALTERNATIVE
+ ASM_CLAC ::: "memory", "flags");
+}
+
static inline long
privcmd_call(unsigned int call,
unsigned long a1, unsigned long a2,
@@ -225,9 +241,9 @@ privcmd_call(unsigned int call,
{
long res;
- stac();
+ __xen_stac();
res = xen_single_call(call, a1, a2, a3, a4, a5);
- clac();
+ __xen_clac();
return res;
}
@@ -424,9 +440,9 @@ HYPERVISOR_dm_op(
domid_t dom, unsigned int nr_bufs, struct xen_dm_op_buf *bufs)
{
int ret;
- stac();
+ __xen_stac();
ret = _hypercall3(int, dm_op, dom, nr_bufs, bufs);
- clac();
+ __xen_clac();
return ret;
}
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index e471d8e6f0b2..70933193878c 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -127,6 +127,13 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
struct task_struct *tsk;
int err;
+ /*
+ * For a new task use the RESET flags value since there is no before.
+ * All the status flags are zero; DF and all the system flags must also
+ * be 0, specifically IF must be 0 because we context switch to the new
+ * task with interrupts disabled.
+ */
+ frame->flags = X86_EFLAGS_FIXED;
frame->bp = 0;
frame->ret_addr = (unsigned long) ret_from_fork;
p->thread.sp = (unsigned long) fork_frame;
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 6a62f4af9fcf..844a28b29967 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -392,6 +392,7 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
childregs = task_pt_regs(p);
fork_frame = container_of(childregs, struct fork_frame, regs);
frame = &fork_frame->frame;
+
frame->bp = 0;
frame->ret_addr = (unsigned long) ret_from_fork;
p->thread.sp = (unsigned long) fork_frame;
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 08dfd4c1a4f9..c8aa58a2bab9 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -132,16 +132,6 @@ static int restore_sigcontext(struct pt_regs *regs,
COPY_SEG_CPL3(cs);
COPY_SEG_CPL3(ss);
-#ifdef CONFIG_X86_64
- /*
- * Fix up SS if needed for the benefit of old DOSEMU and
- * CRIU.
- */
- if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) &&
- user_64bit_mode(regs)))
- force_valid_ss(regs);
-#endif
-
get_user_ex(tmpflags, &sc->flags);
regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
regs->orig_ax = -1; /* disable syscall checks */
@@ -150,6 +140,15 @@ static int restore_sigcontext(struct pt_regs *regs,
buf = (void __user *)buf_val;
} get_user_catch(err);
+#ifdef CONFIG_X86_64
+ /*
+ * Fix up SS if needed for the benefit of old DOSEMU and
+ * CRIU.
+ */
+ if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs)))
+ force_valid_ss(regs);
+#endif
+
err |= fpu__restore_sig(buf, IS_ENABLED(CONFIG_X86_32));
force_iret();
@@ -461,6 +460,7 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
{
struct rt_sigframe __user *frame;
void __user *fp = NULL;
+ unsigned long uc_flags;
int err = 0;
frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
@@ -473,9 +473,11 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
return -EFAULT;
}
+ uc_flags = frame_uc_flags(regs);
+
put_user_try {
/* Create the ucontext. */
- put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags);
+ put_user_ex(uc_flags, &frame->uc.uc_flags);
put_user_ex(0, &frame->uc.uc_link);
save_altstack_ex(&frame->uc.uc_stack, regs->sp);
@@ -541,6 +543,7 @@ static int x32_setup_rt_frame(struct ksignal *ksig,
{
#ifdef CONFIG_X86_X32_ABI
struct rt_sigframe_x32 __user *frame;
+ unsigned long uc_flags;
void __user *restorer;
int err = 0;
void __user *fpstate = NULL;
@@ -555,9 +558,11 @@ static int x32_setup_rt_frame(struct ksignal *ksig,
return -EFAULT;
}
+ uc_flags = frame_uc_flags(regs);
+
put_user_try {
/* Create the ucontext. */
- put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags);
+ put_user_ex(uc_flags, &frame->uc.uc_flags);
put_user_ex(0, &frame->uc.uc_link);
compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
put_user_ex(0, &frame->uc.uc__pad0);
diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S
index db4e5aa0858b..b2f1822084ae 100644
--- a/arch/x86/lib/copy_user_64.S
+++ b/arch/x86/lib/copy_user_64.S
@@ -16,6 +16,30 @@
#include <asm/smap.h>
#include <asm/export.h>
+.macro ALIGN_DESTINATION
+ /* check for bad alignment of destination */
+ movl %edi,%ecx
+ andl $7,%ecx
+ jz 102f /* already aligned */
+ subl $8,%ecx
+ negl %ecx
+ subl %ecx,%edx
+100: movb (%rsi),%al
+101: movb %al,(%rdi)
+ incq %rsi
+ incq %rdi
+ decl %ecx
+ jnz 100b
+102:
+ .section .fixup,"ax"
+103: addl %ecx,%edx /* ecx is zerorest also */
+ jmp copy_user_handle_tail
+ .previous
+
+ _ASM_EXTABLE_UA(100b, 103b)
+ _ASM_EXTABLE_UA(101b, 103b)
+ .endm
+
/*
* copy_user_generic_unrolled - memory copy with exception handling.
* This version is for CPUs like P4 that don't have efficient micro
@@ -194,6 +218,30 @@ ENDPROC(copy_user_enhanced_fast_string)
EXPORT_SYMBOL(copy_user_enhanced_fast_string)
/*
+ * Try to copy last bytes and clear the rest if needed.
+ * Since protection fault in copy_from/to_user is not a normal situation,
+ * it is not necessary to optimize tail handling.
+ *
+ * Input:
+ * rdi destination
+ * rsi source
+ * rdx count
+ *
+ * Output:
+ * eax uncopied bytes or 0 if successful.
+ */
+ALIGN;
+copy_user_handle_tail:
+ movl %edx,%ecx
+1: rep movsb
+2: mov %ecx,%eax
+ ASM_CLAC
+ ret
+
+ _ASM_EXTABLE_UA(1b, 2b)
+ENDPROC(copy_user_handle_tail)
+
+/*
* copy_user_nocache - Uncached memory copy with exception handling
* This will force destination out of cache for more performance.
*
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index 3b24dc05251c..9d05572370ed 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -257,6 +257,7 @@ ENTRY(__memcpy_mcsafe)
/* Copy successful. Return zero */
.L_done_memcpy_trap:
xorl %eax, %eax
+.L_done:
ret
ENDPROC(__memcpy_mcsafe)
EXPORT_SYMBOL_GPL(__memcpy_mcsafe)
@@ -273,7 +274,7 @@ EXPORT_SYMBOL_GPL(__memcpy_mcsafe)
addl %edx, %ecx
.E_trailing_bytes:
mov %ecx, %eax
- ret
+ jmp .L_done
/*
* For write fault handling, given the destination is unaligned,
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
index ee42bb0cbeb3..9952a01cad24 100644
--- a/arch/x86/lib/usercopy_64.c
+++ b/arch/x86/lib/usercopy_64.c
@@ -55,26 +55,6 @@ unsigned long clear_user(void __user *to, unsigned long n)
EXPORT_SYMBOL(clear_user);
/*
- * Try to copy last bytes and clear the rest if needed.
- * Since protection fault in copy_from/to_user is not a normal situation,
- * it is not necessary to optimize tail handling.
- */
-__visible unsigned long
-copy_user_handle_tail(char *to, char *from, unsigned len)
-{
- for (; len; --len, to++) {
- char c;
-
- if (__get_user_nocheck(c, from++, sizeof(char)))
- break;
- if (__put_user_nocheck(c, to, sizeof(char)))
- break;
- }
- clac();
- return len;
-}
-
-/*
* Similar to copy_user_handle_tail, probe for the write fault point,
* but reuse __memcpy_mcsafe in case a new read error is encountered.
* clac() is handled in _copy_to_iter_mcsafe().