[RFC][PATCH 22/22] kill uaccess_try()

From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [RFC][PATCH 22/22] kill uaccess_try()
Date: Mon, 23 Mar 2020 18:38:19 +0000	[thread overview]
Message-ID: <20200323183819.250124-22-viro@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20200323183819.250124-1-viro@ZenIV.linux.org.uk>

From: Al Viro <viro@zeniv.linux.org.uk>

finally

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 Documentation/x86/exception-tables.rst |  6 ----
 arch/x86/include/asm/asm.h             |  6 ----
 arch/x86/include/asm/processor.h       |  1 -
 arch/x86/include/asm/uaccess.h         | 65 ----------------------------------
 arch/x86/mm/extable.c                  | 12 -------
 5 files changed, 90 deletions(-)

diff --git a/Documentation/x86/exception-tables.rst b/Documentation/x86/exception-tables.rst
index ed6d4b0cf62c..514f51829da7 100644
--- a/Documentation/x86/exception-tables.rst
+++ b/Documentation/x86/exception-tables.rst
@@ -337,10 +337,4 @@ pointer which points to one of:
      entry->insn. It is used to distinguish page faults from machine
      check.
 
-3) ``int ex_handler_ext(const struct exception_table_entry *fixup)``
-     This case is used for uaccess_err ... we need to set a flag
-     in the task structure. Before the handler functions existed this
-     case was handled by adding a large offset to the fixup to tag
-     it as special.
-
 More functions can easily be added.
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index cd339b88d5d4..0f63585edf5f 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -138,9 +138,6 @@
 # define _ASM_EXTABLE_FAULT(from, to)				\
 	_ASM_EXTABLE_HANDLE(from, to, ex_handler_fault)
 
-# define _ASM_EXTABLE_EX(from, to)				\
-	_ASM_EXTABLE_HANDLE(from, to, ex_handler_ext)
-
 # define _ASM_NOKPROBE(entry)					\
 	.pushsection "_kprobe_blacklist","aw" ;			\
 	_ASM_ALIGN ;						\
@@ -166,9 +163,6 @@
 # define _ASM_EXTABLE_FAULT(from, to)				\
 	_ASM_EXTABLE_HANDLE(from, to, ex_handler_fault)
 
-# define _ASM_EXTABLE_EX(from, to)				\
-	_ASM_EXTABLE_HANDLE(from, to, ex_handler_ext)
-
 /* For C file, we already have NOKPROBE_SYMBOL macro */
 #endif
 
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 09705ccc393c..19718fcfdd6a 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -541,7 +541,6 @@ struct thread_struct {
 	mm_segment_t		addr_limit;
 
 	unsigned int		sig_on_uaccess_err:1;
-	unsigned int		uaccess_err:1;	/* uaccess failed */
 
 	/* Floating point and extended processor state */
 	struct fpu		fpu;
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 4dc5accdd826..d11662f753d2 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -193,23 +193,12 @@ __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 		     : : "A" (x), "r" (addr)			\
 		     : : label)
 
-#define __put_user_asm_ex_u64(x, addr)					\
-	asm volatile("\n"						\
-		     "1:	movl %%eax,0(%1)\n"			\
-		     "2:	movl %%edx,4(%1)\n"			\
-		     "3:"						\
-		     _ASM_EXTABLE_EX(1b, 2b)				\
-		     _ASM_EXTABLE_EX(2b, 3b)				\
-		     : : "A" (x), "r" (addr))
-
 #define __put_user_x8(x, ptr, __ret_pu)				\
 	asm volatile("call __put_user_8" : "=a" (__ret_pu)	\
 		     : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 #else
 #define __put_user_goto_u64(x, ptr, label) \
 	__put_user_goto(x, ptr, "q", "", "er", label)
-#define __put_user_asm_ex_u64(x, addr)	\
-	__put_user_asm_ex(x, addr, "q", "", "er")
 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 #endif
 
@@ -289,31 +278,6 @@ do {									\
 	}								\
 } while (0)
 
-/*
- * This doesn't do __uaccess_begin/end - the exception handling
- * around it must do that.
- */
-#define __put_user_size_ex(x, ptr, size)				\
-do {									\
-	__chk_user_ptr(ptr);						\
-	switch (size) {							\
-	case 1:								\
-		__put_user_asm_ex(x, ptr, "b", "b", "iq");		\
-		break;							\
-	case 2:								\
-		__put_user_asm_ex(x, ptr, "w", "w", "ir");		\
-		break;							\
-	case 4:								\
-		__put_user_asm_ex(x, ptr, "l", "k", "ir");		\
-		break;							\
-	case 8:								\
-		__put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);	\
-		break;							\
-	default:							\
-		__put_user_bad();					\
-	}								\
-} while (0)
-
 #ifdef CONFIG_X86_32
 #define __get_user_asm_u64(x, ptr, retval, errret)			\
 ({									\
@@ -430,29 +394,6 @@ struct __large_struct { unsigned long buf[100]; };
 	retval = __put_user_failed(x, addr, itype, rtype, ltype, errret);	\
 } while (0)
 
-#define __put_user_asm_ex(x, addr, itype, rtype, ltype)			\
-	asm volatile("1:	mov"itype" %"rtype"0,%1\n"		\
-		     "2:\n"						\
-		     _ASM_EXTABLE_EX(1b, 2b)				\
-		     : : ltype(x), "m" (__m(addr)))
-
-/*
- * uaccess_try and catch
- */
-#define uaccess_try	do {						\
-	current->thread.uaccess_err = 0;				\
-	__uaccess_begin();						\
-	barrier();
-
-#define uaccess_try_nospec do {						\
-	current->thread.uaccess_err = 0;				\
-	__uaccess_begin_nospec();					\
-
-#define uaccess_catch(err)						\
-	__uaccess_end();						\
-	(err) |= (current->thread.uaccess_err ? -EFAULT : 0);		\
-} while (0)
-
 /**
  * __get_user - Get a simple variable from user space, with less checking.
  * @x:   Variable to store result.
@@ -502,12 +443,6 @@ struct __large_struct { unsigned long buf[100]; };
 #define __put_user(x, ptr)						\
 	__put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 
-#define put_user_try		uaccess_try
-#define put_user_catch(err)	uaccess_catch(err)
-
-#define put_user_ex(x, ptr)						\
-	__put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
-
 extern unsigned long
 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 extern __must_check long
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index 30bb0bd3b1b8..b991aa4bdfae 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -80,18 +80,6 @@ __visible bool ex_handler_uaccess(const struct exception_table_entry *fixup,
 }
 EXPORT_SYMBOL(ex_handler_uaccess);
 
-__visible bool ex_handler_ext(const struct exception_table_entry *fixup,
-			      struct pt_regs *regs, int trapnr,
-			      unsigned long error_code,
-			      unsigned long fault_addr)
-{
-	/* Special hack for uaccess_err */
-	current->thread.uaccess_err = 1;
-	regs->ip = ex_fixup_addr(fixup);
-	return true;
-}
-EXPORT_SYMBOL(ex_handler_ext);
-
 __visible bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup,
 				       struct pt_regs *regs, int trapnr,
 				       unsigned long error_code,
-- 
2.11.0

