linux-kernel - [PATCH 2/4] x86, putuser: copy pasta into 32 and 64-bit versions

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Message-ID: <20190316210239.GB21830@avx2>
Date:   Sun, 17 Mar 2019 00:02:39 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] x86, putuser: copy pasta into 32 and 64-bit versions

I'm going to rewrite 64-bit version to use normal x86_64 calling convention.

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---

 arch/x86/lib/Makefile     |    3 -
 arch/x86/lib/putuser_64.S |  103 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+), 1 deletion(-)

--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -21,7 +21,8 @@ clean-files := inat-tables.c
 obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o
 
 lib-y := delay.o misc.o cmdline.o cpu.o
-lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o
+lib-y += usercopy_$(BITS).o usercopy.o getuser.o
+lib-y += putuser_$(BITS).o
 lib-y += memcpy_$(BITS).o
 lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
 lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o insn-eval.o
similarity index 100%
rename from arch/x86/lib/putuser.S
rename to arch/x86/lib/putuser_32.S
new file mode 100644
--- /dev/null
+++ b/arch/x86/lib/putuser_64.S
@@ -0,0 +1,103 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * __put_user functions.
+ *
+ * (C) Copyright 2005 Linus Torvalds
+ * (C) Copyright 2005 Andi Kleen
+ * (C) Copyright 2008 Glauber Costa
+ *
+ * These functions have a non-standard call interface
+ * to make them more efficient, especially as they
+ * return an error value in addition to the "real"
+ * return value.
+ */
+#include <linux/linkage.h>
+#include <asm/thread_info.h>
+#include <asm/errno.h>
+#include <asm/asm.h>
+#include <asm/smap.h>
+#include <asm/export.h>
+
+
+/*
+ * __put_user_X
+ *
+ * Inputs:	%eax[:%edx] contains the data
+ *		%ecx contains the address
+ *
+ * Outputs:	%eax is error code (0 or -EFAULT)
+ *
+ * These functions should not modify any other registers,
+ * as they get called from within inline assembly.
+ */
+
+#define ENTER	mov PER_CPU_VAR(current_task), %_ASM_BX
+#define EXIT	ASM_CLAC ;	\
+		ret
+
+.text
+ENTRY(__put_user_1)
+	ENTER
+	cmp TASK_addr_limit(%_ASM_BX),%_ASM_CX
+	jae bad_put_user
+	ASM_STAC
+1:	movb %al,(%_ASM_CX)
+	xor %eax,%eax
+	EXIT
+ENDPROC(__put_user_1)
+EXPORT_SYMBOL(__put_user_1)
+
+ENTRY(__put_user_2)
+	ENTER
+	mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
+	sub $1,%_ASM_BX
+	cmp %_ASM_BX,%_ASM_CX
+	jae bad_put_user
+	ASM_STAC
+2:	movw %ax,(%_ASM_CX)
+	xor %eax,%eax
+	EXIT
+ENDPROC(__put_user_2)
+EXPORT_SYMBOL(__put_user_2)
+
+ENTRY(__put_user_4)
+	ENTER
+	mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
+	sub $3,%_ASM_BX
+	cmp %_ASM_BX,%_ASM_CX
+	jae bad_put_user
+	ASM_STAC
+3:	movl %eax,(%_ASM_CX)
+	xor %eax,%eax
+	EXIT
+ENDPROC(__put_user_4)
+EXPORT_SYMBOL(__put_user_4)
+
+ENTRY(__put_user_8)
+	ENTER
+	mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
+	sub $7,%_ASM_BX
+	cmp %_ASM_BX,%_ASM_CX
+	jae bad_put_user
+	ASM_STAC
+4:	mov %_ASM_AX,(%_ASM_CX)
+#ifdef CONFIG_X86_32
+5:	movl %edx,4(%_ASM_CX)
+#endif
+	xor %eax,%eax
+	EXIT
+ENDPROC(__put_user_8)
+EXPORT_SYMBOL(__put_user_8)
+
+bad_put_user:
+	movl $-EFAULT,%eax
+	EXIT
+END(bad_put_user)
+
+	_ASM_EXTABLE_UA(1b, bad_put_user)
+	_ASM_EXTABLE_UA(2b, bad_put_user)
+	_ASM_EXTABLE_UA(3b, bad_put_user)
+	_ASM_EXTABLE_UA(4b, bad_put_user)
+#ifdef CONFIG_X86_32
+	_ASM_EXTABLE_UA(5b, bad_put_user)
+#endif