From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755091AbdJIN6R (ORCPT ); Mon, 9 Oct 2017 09:58:17 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41875 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754187AbdJIMo6 (ORCPT ); Mon, 9 Oct 2017 08:44:58 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Tony Lindgren" , "Kevin Hilman" , "Kevin Hilman" Date: Mon, 09 Oct 2017 13:44:25 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 162/192] ARM: OMAP3: Fix booting with thumb2 kernel In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.49-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Tony Lindgren commit d8a50941c91a68da202aaa96a3dacd471ea9c693 upstream. We get a NULL pointer dereference on omap3 for thumb2 compiled kernels: Internal error: Oops: 80000005 [#1] SMP THUMB2 ... [] (_raw_spin_unlock_irqrestore) from [] (omap3_enter_idle_bm+0xc5/0x178) [] (omap3_enter_idle_bm) from [] (cpuidle_enter_state+0x77/0x27c) [] (cpuidle_enter_state) from [] (cpu_startup_entry+0x155/0x23c) [] (cpu_startup_entry) from [] (start_kernel+0x32f/0x338) [] (start_kernel) from [<8000807f>] (0x8000807f) The power management related assembly on omaps needs to interact with ARM mode bootrom code, so we need to keep most of the related assembly in ARM mode. Turns out this error is because of missing ENDPROC for assembly code as suggested by Stephen Boyd . Let's fix the problem by adding ENDPROC in two places to sleep34xx.S. Let's also remove the now duplicate custom code for mode switching. This has been unnecessary since commit 6ebbf2ce437b ("ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+"). And let's also remove the comments about local variables, they are now just confusing after the ENDPROC. The reason why ENDPROC makes a difference is it sets .type and then the compiler knows what to do with the thumb bit as explained at: https://wiki.ubuntu.com/ARM/Thumb2PortingHowto Reported-by: Kevin Hilman Tested-by: Kevin Hilman Signed-off-by: Tony Lindgren Signed-off-by: Ben Hutchings --- arch/arm/mach-omap2/sleep34xx.S | 22 ++-------------------- 1 file changed, 2 insertions(+), 20 deletions(-) --- a/arch/arm/mach-omap2/sleep34xx.S +++ b/arch/arm/mach-omap2/sleep34xx.S @@ -203,23 +203,8 @@ save_context_wfi: */ ldr r1, kernel_flush blx r1 - /* - * The kernel doesn't interwork: v7_flush_dcache_all in particluar will - * always return in Thumb state when CONFIG_THUMB2_KERNEL is enabled. - * This sequence switches back to ARM. Note that .align may insert a - * nop: bx pc needs to be word-aligned in order to work. - */ - THUMB( .thumb ) - THUMB( .align ) - THUMB( bx pc ) - THUMB( nop ) - .arm - b omap3_do_wfi - -/* - * Local variables - */ +ENDPROC(omap34xx_cpu_suspend) omap3_do_wfi_sram_addr: .word omap3_do_wfi_sram kernel_flush: @@ -364,10 +349,7 @@ exit_nonoff_modes: * =================================== */ ldmfd sp!, {r4 - r11, pc} @ restore regs and return - -/* - * Local variables - */ +ENDPROC(omap3_do_wfi) sdrc_power: .word SDRC_POWER_V cm_idlest1_core: