5 files changed, 31 insertions, 10 deletions

diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 69b74a7b877f..3b5b828767b6 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -125,11 +125,16 @@ static inline void alternatives_smp_switch(int smp) {}
         asm volatile (ALTERNATIVE(oldinstr, newinstr, feature)          \
                 : output : "i" (0), ## input)
 
+/* Like alternative_io, but for replacing a direct call with another one. */
+#define alternative_call(oldfunc, newfunc, feature, output, input...)   \
+        asm volatile (ALTERNATIVE("call %P[old]", "call %P[new]", feature) \
+                : output : [old] "i" (oldfunc), [new] "i" (newfunc), ## input)
+
 /*
  * use this macro(s) if you need more than one output parameter
  * in alternative_io
  */
-#define ASM_OUTPUT2(a, b) a, b
+#define ASM_OUTPUT2(a...) a
 
 struct paravirt_patch_site;
 #ifdef CONFIG_PARAVIRT
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index 46324c6a4f6e..a78c40305447 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -8,6 +8,8 @@
 #include <linux/errno.h>
 #include <linux/prefetch.h>
 #include <linux/lockdep.h>
+#include <asm/alternative.h>
+#include <asm/cpufeature.h>
 #include <asm/page.h>
 
 /*
@@ -16,7 +18,24 @@
 
 /* Handles exceptions in both to and from, but doesn't do access_ok */
 __must_check unsigned long
-copy_user_generic(void *to, const void *from, unsigned len);
+copy_user_generic_string(void *to, const void *from, unsigned len);
+__must_check unsigned long
+copy_user_generic_unrolled(void *to, const void *from, unsigned len);
+
+static __always_inline __must_check unsigned long
+copy_user_generic(void *to, const void *from, unsigned len)
+{
+        unsigned ret;
+
+        alternative_call(copy_user_generic_unrolled,
+                         copy_user_generic_string,
+                         X86_FEATURE_REP_GOOD,
+                         ASM_OUTPUT2("=a" (ret), "=D" (to), "=S" (from),
+                                     "=d" (len)),
+                         "1" (to), "2" (from), "3" (len)
+                         : "memory", "rcx", "r8", "r9", "r10", "r11");
+        return ret;
+}
 
 __must_check unsigned long
 _copy_to_user(void __user *to, const void *from, unsigned len);
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index de7353c0ce9c..2589ea4c60ce 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -205,7 +205,7 @@ void __init_or_module apply_alternatives(struct alt_instr *start,
                                          struct alt_instr *end)
 {
         struct alt_instr *a;
-        char insnbuf[MAX_PATCH_LEN];
+        u8 insnbuf[MAX_PATCH_LEN];
 
         DPRINTK("%s: alt table %p -> %p\n", __func__, start, end);
         for (a = start; a < end; a++) {
@@ -223,6 +223,8 @@ void __init_or_module apply_alternatives(struct alt_instr *start,
                 }
 #endif
                 memcpy(insnbuf, a->replacement, a->replacementlen);
+                if (*insnbuf == 0xe8 && a->replacementlen == 5)
+                    *(s32 *)(insnbuf + 1) += a->replacement - a->instr;
                 add_nops(insnbuf + a->replacementlen,
                          a->instrlen - a->replacementlen);
                 text_poke_early(instr, insnbuf, a->instrlen);
diff --git a/arch/x86/kernel/x8664_ksyms_64.c b/arch/x86/kernel/x8664_ksyms_64.c
index 619f7f88b8cc..693920b22496 100644
--- a/arch/x86/kernel/x8664_ksyms_64.c
+++ b/arch/x86/kernel/x8664_ksyms_64.c
@@ -26,7 +26,8 @@ EXPORT_SYMBOL(__put_user_2);
 EXPORT_SYMBOL(__put_user_4);
 EXPORT_SYMBOL(__put_user_8);
 
-EXPORT_SYMBOL(copy_user_generic);
+EXPORT_SYMBOL(copy_user_generic_string);
+EXPORT_SYMBOL(copy_user_generic_unrolled);
 EXPORT_SYMBOL(__copy_user_nocache);
 EXPORT_SYMBOL(_copy_from_user);
 EXPORT_SYMBOL(_copy_to_user);
diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S
index cf889d4e076a..71100c98e337 100644
--- a/arch/x86/lib/copy_user_64.S
+++ b/arch/x86/lib/copy_user_64.S
@@ -90,12 +90,6 @@ ENTRY(_copy_from_user)
         CFI_ENDPROC
 ENDPROC(_copy_from_user)
 
-ENTRY(copy_user_generic)
-        CFI_STARTPROC
-        ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,copy_user_generic_unrolled,copy_user_generic_string
-        CFI_ENDPROC
-ENDPROC(copy_user_generic)
-
         .section .fixup,"ax"
         /* must zero dest */
 ENTRY(bad_from_user)