From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:51184 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1163791AbdD1HqT (ORCPT ); Fri, 28 Apr 2017 03:46:19 -0400 Subject: Patch "ARM: 8383/1: nommu: avoid deprecated source register on mov" has been added to the 3.18-stable tree To: stefan@agner.ch, arnd@arndb.de, gregkh@linuxfoundation.org, mcoquelin.stm32@gmail.com, rmk+kernel@arm.linux.org.uk Cc: , From: Date: Fri, 28 Apr 2017 09:46:09 +0200 Message-ID: <1493365569203121@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled ARM: 8383/1: nommu: avoid deprecated source register on mov to the 3.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: arm-8383-1-nommu-avoid-deprecated-source-register-on-mov.patch and it can be found in the queue-3.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 970d96f9a81b0dd83ddd8bce0e5e1ba31881c5f5 Mon Sep 17 00:00:00 2001 From: Stefan Agner Date: Tue, 2 Jun 2015 20:43:24 +0100 Subject: ARM: 8383/1: nommu: avoid deprecated source register on mov From: Stefan Agner commit 970d96f9a81b0dd83ddd8bce0e5e1ba31881c5f5 upstream. In Thumb2 mode, the stack register r13 is deprecated if the destination register is the program counter (r15). Similar to head.S, head-nommu.S uses r13 to store the return address used after configuring the CPU's CP15 register. However, since we do not enable a MMU, there will be no address switch and it is possible to use branch with link instruction to call __after_proc_init. Avoid using r13 completely by using bl to call __after_proc_init and get rid of __secondary_switched. Beside removing unnecessary complexity, this also fixes a compiler warning when compiling a !MMU kernel: Warning: Use of r13 as a source register is deprecated when r15 is the destination register. Tested-by: Maxime Coquelin Signed-off-by: Stefan Agner Signed-off-by: Russell King Signed-off-by: Arnd Bergmann Signed-off-by: Greg Kroah-Hartman --- arch/arm/kernel/head-nommu.S | 20 +++++++------------- 1 file changed, 7 insertions(+), 13 deletions(-) --- a/arch/arm/kernel/head-nommu.S +++ b/arch/arm/kernel/head-nommu.S @@ -77,13 +77,12 @@ ENTRY(stext) orr r6, r6, #(1 << MPU_RSR_EN) @ Set region enabled bit bl __setup_mpu #endif - ldr r13, =__mmap_switched @ address to jump to after - @ initialising sctlr adr lr, BSYM(1f) @ return (PIC) address ARM( add pc, r10, #PROCINFO_INITFUNC ) THUMB( add r12, r10, #PROCINFO_INITFUNC ) THUMB( ret r12 ) - 1: b __after_proc_init +1: bl __after_proc_init + b __mmap_switched ENDPROC(stext) #ifdef CONFIG_SMP @@ -106,8 +105,7 @@ ENTRY(secondary_startup) movs r10, r5 @ invalid processor? beq __error_p @ yes, error 'p' - adr r4, __secondary_data - ldmia r4, {r7, r12} + ldr r7, __secondary_data #ifdef CONFIG_ARM_MPU /* Use MPU region info supplied by __cpu_up */ @@ -115,23 +113,19 @@ ENTRY(secondary_startup) bl __setup_mpu @ Initialize the MPU #endif - adr lr, BSYM(__after_proc_init) @ return address - mov r13, r12 @ __secondary_switched address + adr lr, BSYM(1f) @ return (PIC) address ARM( add pc, r10, #PROCINFO_INITFUNC ) THUMB( add r12, r10, #PROCINFO_INITFUNC ) THUMB( ret r12 ) -ENDPROC(secondary_startup) - -ENTRY(__secondary_switched) +1: bl __after_proc_init ldr sp, [r7, #8] @ set up the stack pointer mov fp, #0 b secondary_start_kernel -ENDPROC(__secondary_switched) +ENDPROC(secondary_startup) .type __secondary_data, %object __secondary_data: .long secondary_data - .long __secondary_switched #endif /* CONFIG_SMP */ /* @@ -164,7 +158,7 @@ __after_proc_init: #endif mcr p15, 0, r0, c1, c0, 0 @ write control reg #endif /* CONFIG_CPU_CP15 */ - ret r13 + ret lr ENDPROC(__after_proc_init) .ltorg Patches currently in stable-queue which might be from stefan@agner.ch are queue-3.18/arm-8383-1-nommu-avoid-deprecated-source-register-on-mov.patch