Message-ID: <e16e2ce5-dc21-d159-ecf2-e0a430d772e1@collabora.com>
Date:   Fri, 13 Nov 2020 10:31:03 +0000
From:   Guillaume Tucker <guillaume.tucker@...labora.com>
To:     Ard Biesheuvel <ardb@...nel.org>, Nicolas Pitre <nico@...xnic.net>,
        Linus Walleij <linus.walleij@...aro.org>,
        Russell King <rmk+kernel@...linux.org.uk>
Cc:     kernelci-results@...ups.io, linux-arm-kernel@...ts.infradead.org,
        Olof Johansson <olof@...om.net>,
        Mike Rapoport <rppt@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Marc Zyngier <maz@...nel.org>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Collabora Kernel ML <kernel@...labora.com>
Subject: Re: rmk/for-next bisection: baseline.login on bcm2836-rpi-2-b

Hi Ard,

Please see the bisection report below about a boot failure on
RPi-2b.

Reports aren't automatically sent to the public while we're
trialing new bisection features on kernelci.org but this one
looks valid.

There's nothing in the serial console log, probably because it's
crashing too early during boot.  I'm not sure if other platforms
on kernelci.org were hit by this in the same way, but there
doesn't seem to be any.

The same regression can be see on rmk's for-next branch as well
as in linux-next.  It happens with both bcm2835_defconfig and
multi_v7_defconfig.

Some more details can be found here:

  https://kernelci.org/test/case/id/5fae44823818ee918adb8864/

If this looks like a real issue but you don't have a platform at
hand to reproduce it, please let us know if you would like the
KernelCI test to be re-run with earlyprintk or some debug config
turned on, or if you have a fix to try.

Best wishes,
Guillaume



On 13/11/2020 02:27, KernelCI bot wrote:
> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> * This automated bisection report was sent to you on the basis  *
> * that you may be involved with the breaking commit it has      *
> * found.  No manual investigation has been done to verify it,   *
> * and the root cause of the problem may be somewhere else.      *
> *                                                               *
> * If you do send a fix, please include this trailer:            *
> *   Reported-by: "kernelci.org bot" <bot@...nelci.org>          *
> *                                                               *
> * Hope this helps!                                              *
> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> 
> rmk/for-next bisection: baseline.login on bcm2836-rpi-2-b
> 
> Summary:
>   Start:      40bd54f12902 Merge branch 'devel-stable' into for-next
>   Plain log:  https://storage.kernelci.org/rmk/for-next/for-linus-35-g40bd54f129026/arm/bcm2835_defconfig/gcc-8/lab-collabora/baseline-bcm2836-rpi-2-b.txt
>   HTML log:   https://storage.kernelci.org/rmk/for-next/for-linus-35-g40bd54f129026/arm/bcm2835_defconfig/gcc-8/lab-collabora/baseline-bcm2836-rpi-2-b.html
>   Result:     7a1be318f579 ARM: 9012/1: move device tree mapping out of linear region
> 
> Checks:
>   revert:     PASS
>   verify:     PASS
> 
> Parameters:
>   Tree:       rmk
>   URL:        git://git.armlinux.org.uk/~rmk/linux-arm.git
>   Branch:     for-next
>   Target:     bcm2836-rpi-2-b
>   CPU arch:   arm
>   Lab:        lab-collabora
>   Compiler:   gcc-8
>   Config:     bcm2835_defconfig
>   Test case:  baseline.login
> 
> Breaking commit found:
> 
> -------------------------------------------------------------------------------
> commit 7a1be318f5795cb66fa0dc86b3ace427fe68057f
> Author: Ard Biesheuvel <ardb@...nel.org>
> Date:   Sun Oct 11 10:21:37 2020 +0100
> 
>     ARM: 9012/1: move device tree mapping out of linear region
>     
>     On ARM, setting up the linear region is tricky, given the constraints
>     around placement and alignment of the memblocks, and how the kernel
>     itself as well as the DT are placed in physical memory.
>     
>     Let's simplify matters a bit, by moving the device tree mapping to the
>     top of the address space, right between the end of the vmalloc region
>     and the start of the the fixmap region, and create a read-only mapping
>     for it that is independent of the size of the linear region, and how it
>     is organized.
>     
>     Since this region was formerly used as a guard region, which will now be
>     populated fully on LPAE builds by this read-only mapping (which will
>     still be able to function as a guard region for stray writes), bump the
>     start of the [underutilized] fixmap region by 512 KB as well, to ensure
>     that there is always a proper guard region here. Doing so still leaves
>     ample room for the fixmap space, even with NR_CPUS set to its maximum
>     value of 32.
>     
>     Tested-by: Linus Walleij <linus.walleij@...aro.org>
>     Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
>     Reviewed-by: Nicolas Pitre <nico@...xnic.net>
>     Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
>     Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
> 
> diff --git a/Documentation/arm/memory.rst b/Documentation/arm/memory.rst
> index 0521b4ce5c96..34bb23c44a71 100644
> --- a/Documentation/arm/memory.rst
> +++ b/Documentation/arm/memory.rst
> @@ -45,9 +45,14 @@ fffe8000	fffeffff	DTCM mapping area for platforms with
>  fffe0000	fffe7fff	ITCM mapping area for platforms with
>  				ITCM mounted inside the CPU.
>  
> -ffc00000	ffefffff	Fixmap mapping region.  Addresses provided
> +ffc80000	ffefffff	Fixmap mapping region.  Addresses provided
>  				by fix_to_virt() will be located here.
>  
> +ffc00000	ffc7ffff	Guard region
> +
> +ff800000	ffbfffff	Permanent, fixed read-only mapping of the
> +				firmware provided DT blob
> +
>  fee00000	feffffff	Mapping of PCI I/O space. This is a static
>  				mapping within the vmalloc space.
>  
> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
> index fc56fc3e1931..9575b404019c 100644
> --- a/arch/arm/include/asm/fixmap.h
> +++ b/arch/arm/include/asm/fixmap.h
> @@ -2,7 +2,7 @@
>  #ifndef _ASM_FIXMAP_H
>  #define _ASM_FIXMAP_H
>  
> -#define FIXADDR_START		0xffc00000UL
> +#define FIXADDR_START		0xffc80000UL
>  #define FIXADDR_END		0xfff00000UL
>  #define FIXADDR_TOP		(FIXADDR_END - PAGE_SIZE)
>  
> diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
> index 99035b5891ef..bb79e52aeb90 100644
> --- a/arch/arm/include/asm/memory.h
> +++ b/arch/arm/include/asm/memory.h
> @@ -67,6 +67,10 @@
>   */
>  #define XIP_VIRT_ADDR(physaddr)  (MODULES_VADDR + ((physaddr) & 0x000fffff))
>  
> +#define FDT_FIXED_BASE		UL(0xff800000)
> +#define FDT_FIXED_SIZE		(2 * PMD_SIZE)
> +#define FDT_VIRT_ADDR(physaddr)	((void *)(FDT_FIXED_BASE | (physaddr) % PMD_SIZE))
> +
>  #if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
>  /*
>   * Allow 16MB-aligned ioremap pages
> @@ -107,6 +111,7 @@ extern unsigned long vectors_base;
>  #define MODULES_VADDR		PAGE_OFFSET
>  
>  #define XIP_VIRT_ADDR(physaddr)  (physaddr)
> +#define FDT_VIRT_ADDR(physaddr)  ((void *)(physaddr))
>  
>  #endif /* !CONFIG_MMU */
>  
> diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
> index f8904227e7fd..9b18d8c66129 100644
> --- a/arch/arm/kernel/head.S
> +++ b/arch/arm/kernel/head.S
> @@ -275,9 +275,8 @@ __create_page_tables:
>  	 */
>  	mov	r0, r2, lsr #SECTION_SHIFT
>  	movs	r0, r0, lsl #SECTION_SHIFT
> -	subne	r3, r0, r8
> -	addne	r3, r3, #PAGE_OFFSET
> -	addne	r3, r4, r3, lsr #(SECTION_SHIFT - PMD_ORDER)
> +	ldrne	r3, =FDT_FIXED_BASE >> (SECTION_SHIFT - PMD_ORDER)
> +	addne	r3, r3, r4
>  	orrne	r6, r7, r0
>  	strne	r6, [r3], #1 << PMD_ORDER
>  	addne	r6, r6, #1 << SECTION_SHIFT
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index 306bcd9844be..694aa6b4bd03 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -18,6 +18,7 @@
>  #include <linux/of_platform.h>
>  #include <linux/init.h>
>  #include <linux/kexec.h>
> +#include <linux/libfdt.h>
>  #include <linux/of_fdt.h>
>  #include <linux/cpu.h>
>  #include <linux/interrupt.h>
> @@ -89,7 +90,6 @@ unsigned int cacheid __read_mostly;
>  EXPORT_SYMBOL(cacheid);
>  
>  unsigned int __atags_pointer __initdata;
> -void *atags_vaddr __initdata;
>  
>  unsigned int system_rev;
>  EXPORT_SYMBOL(system_rev);
> @@ -1083,13 +1083,18 @@ void __init hyp_mode_check(void)
>  void __init setup_arch(char **cmdline_p)
>  {
>  	const struct machine_desc *mdesc = NULL;
> +	void *atags_vaddr = NULL;
>  
>  	if (__atags_pointer)
> -		atags_vaddr = phys_to_virt(__atags_pointer);
> +		atags_vaddr = FDT_VIRT_ADDR(__atags_pointer);
>  
>  	setup_processor();
> -	if (atags_vaddr)
> +	if (atags_vaddr) {
>  		mdesc = setup_machine_fdt(atags_vaddr);
> +		if (mdesc)
> +			memblock_reserve(__atags_pointer,
> +					 fdt_totalsize(atags_vaddr));
> +	}
>  	if (!mdesc)
>  		mdesc = setup_machine_tags(atags_vaddr, __machine_arch_type);
>  	if (!mdesc) {
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index d57112a276f5..a391804c7ce3 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -223,7 +223,6 @@ void __init arm_memblock_init(const struct machine_desc *mdesc)
>  	if (mdesc->reserve)
>  		mdesc->reserve();
>  
> -	early_init_fdt_reserve_self();
>  	early_init_fdt_scan_reserved_mem();
>  
>  	/* reserve memory for DMA contiguous allocations */
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index 55991fe60054..fa259825310c 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -39,6 +39,8 @@
>  #include "mm.h"
>  #include "tcm.h"
>  
> +extern unsigned long __atags_pointer;
> +
>  /*
>   * empty_zero_page is a special page that is used for
>   * zero-initialized data and COW.
> @@ -946,7 +948,7 @@ static void __init create_mapping(struct map_desc *md)
>  		return;
>  	}
>  
> -	if ((md->type == MT_DEVICE || md->type == MT_ROM) &&
> +	if (md->type == MT_DEVICE &&
>  	    md->virtual >= PAGE_OFFSET && md->virtual < FIXADDR_START &&
>  	    (md->virtual < VMALLOC_START || md->virtual >= VMALLOC_END)) {
>  		pr_warn("BUG: mapping for 0x%08llx at 0x%08lx out of vmalloc space\n",
> @@ -1333,6 +1335,15 @@ static void __init devicemaps_init(const struct machine_desc *mdesc)
>  	for (addr = VMALLOC_START; addr < (FIXADDR_TOP & PMD_MASK); addr += PMD_SIZE)
>  		pmd_clear(pmd_off_k(addr));
>  
> +	if (__atags_pointer) {
> +		/* create a read-only mapping of the device tree */
> +		map.pfn = __phys_to_pfn(__atags_pointer & SECTION_MASK);
> +		map.virtual = FDT_FIXED_BASE;
> +		map.length = FDT_FIXED_SIZE;
> +		map.type = MT_ROM;
> +		create_mapping(&map);
> +	}
> +
>  	/*
>  	 * Map the kernel if it is XIP.
>  	 * It is always first in the modulearea.
> @@ -1489,8 +1500,7 @@ static void __init map_lowmem(void)
>  }
>  
>  #ifdef CONFIG_ARM_PV_FIXUP
> -extern void *atags_vaddr;
> -typedef void pgtables_remap(long long offset, unsigned long pgd, void *bdata);
> +typedef void pgtables_remap(long long offset, unsigned long pgd);
>  pgtables_remap lpae_pgtables_remap_asm;
>  
>  /*
> @@ -1503,7 +1513,6 @@ static void __init early_paging_init(const struct machine_desc *mdesc)
>  	unsigned long pa_pgd;
>  	unsigned int cr, ttbcr;
>  	long long offset;
> -	void *boot_data;
>  
>  	if (!mdesc->pv_fixup)
>  		return;
> @@ -1520,7 +1529,6 @@ static void __init early_paging_init(const struct machine_desc *mdesc)
>  	 */
>  	lpae_pgtables_remap = (pgtables_remap *)(unsigned long)__pa(lpae_pgtables_remap_asm);
>  	pa_pgd = __pa(swapper_pg_dir);
> -	boot_data = atags_vaddr;
>  	barrier();
>  
>  	pr_info("Switching physical address space to 0x%08llx\n",
> @@ -1556,7 +1564,7 @@ static void __init early_paging_init(const struct machine_desc *mdesc)
>  	 * needs to be assembly.  It's fairly simple, as we're using the
>  	 * temporary tables setup by the initial assembly code.
>  	 */
> -	lpae_pgtables_remap(offset, pa_pgd, boot_data);
> +	lpae_pgtables_remap(offset, pa_pgd);
>  
>  	/* Re-enable the caches and cacheable TLB walks */
>  	asm volatile("mcr p15, 0, %0, c2, c0, 2" : : "r" (ttbcr));
> diff --git a/arch/arm/mm/pv-fixup-asm.S b/arch/arm/mm/pv-fixup-asm.S
> index 8eade0416739..5c5e1952000a 100644
> --- a/arch/arm/mm/pv-fixup-asm.S
> +++ b/arch/arm/mm/pv-fixup-asm.S
> @@ -39,8 +39,8 @@ ENTRY(lpae_pgtables_remap_asm)
>  
>  	/* Update level 2 entries for the boot data */
>  	add	r7, r2, #0x1000
> -	add	r7, r7, r3, lsr #SECTION_SHIFT - L2_ORDER
> -	bic	r7, r7, #(1 << L2_ORDER) - 1
> +	movw	r3, #FDT_FIXED_BASE >> (SECTION_SHIFT - L2_ORDER)
> +	add	r7, r7, r3
>  	ldrd	r4, r5, [r7]
>  	adds	r4, r4, r0
>  	adc	r5, r5, r1
> -------------------------------------------------------------------------------
> 
> 
> Git bisection log:
> 
> -------------------------------------------------------------------------------
> git bisect start
> # good: [adc5f7029376049873289be305d507022281b8dd] ARM: add malloc size to decompressor kexec size structure
> git bisect good adc5f7029376049873289be305d507022281b8dd
> # bad: [40bd54f129026a114a76cd6e756659373cf40151] Merge branch 'devel-stable' into for-next
> git bisect bad 40bd54f129026a114a76cd6e756659373cf40151
> # good: [93b694d096cc10994c817730d4d50288f9ae3d66] Merge tag 'drm-next-2020-10-15' of git://anongit.freedesktop.org/drm/drm
> git bisect good 93b694d096cc10994c817730d4d50288f9ae3d66
> # good: [c4cf498dc0241fa2d758dba177634268446afb06] Merge branch 'akpm' (patches from Andrew)
> git bisect good c4cf498dc0241fa2d758dba177634268446afb06
> # good: [ceae608a54898fff2aa0aba358fe81af027ef8c9] Merge tag 'pwm/for-5.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm
> git bisect good ceae608a54898fff2aa0aba358fe81af027ef8c9
> # good: [e731f3146ff3bba5424b40140e1a7e6f92e94964] Merge tag 'armsoc-soc' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc
> git bisect good e731f3146ff3bba5424b40140e1a7e6f92e94964
> # good: [873c331927302ab484c859601982a7cb88bc0723] Merge tag 'stm32-dt-for-v5.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/atorgue/stm32 into arm/dt
> git bisect good 873c331927302ab484c859601982a7cb88bc0723
> # good: [e533cda12d8f0e7936354bafdc85c81741f805d2] Merge tag 'armsoc-dt' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc
> git bisect good e533cda12d8f0e7936354bafdc85c81741f805d2
> # good: [af0041875ce7f5a05362b884e90cf82c27876096] Merge tag 'io_uring-5.10-2020-10-24' of git://git.kernel.dk/linux-block
> git bisect good af0041875ce7f5a05362b884e90cf82c27876096
> # good: [c10037f8323d2a94acb4fc6ecfbab0cda152fdd6] Merge tag '5.10-rc-smb3-fixes-part2' of git://git.samba.org/sfrench/cifs-2.6
> git bisect good c10037f8323d2a94acb4fc6ecfbab0cda152fdd6
> # bad: [421015713b306e47af95d4d61cdfbd96d462e4cb] ARM: 9017/2: Enable KASan for ARM
> git bisect bad 421015713b306e47af95d4d61cdfbd96d462e4cb
> # good: [87702a337f748d19a59a7826aeeffe0f6aeab7d4] Merge tag 'sched-urgent-2020-10-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
> git bisect good 87702a337f748d19a59a7826aeeffe0f6aeab7d4
> # good: [33def8498fdde180023444b08e12b72a9efed41d] treewide: Convert macro and uses of __section(foo) to __section("foo")
> git bisect good 33def8498fdde180023444b08e12b72a9efed41d
> # bad: [d5d44e7e3507b0ad868f68e0c5bca6a57afa1b8b] ARM: 9013/2: Disable KASan instrumentation for some code
> git bisect bad d5d44e7e3507b0ad868f68e0c5bca6a57afa1b8b
> # good: [e9a2f8b599d0bc22a1b13e69527246ac39c697b4] ARM: 9011/1: centralize phys-to-virt conversion of DT/ATAGS address
> git bisect good e9a2f8b599d0bc22a1b13e69527246ac39c697b4
> # bad: [7a1be318f5795cb66fa0dc86b3ace427fe68057f] ARM: 9012/1: move device tree mapping out of linear region
> git bisect bad 7a1be318f5795cb66fa0dc86b3ace427fe68057f
> # first bad commit: [7a1be318f5795cb66fa0dc86b3ace427fe68057f] ARM: 9012/1: move device tree mapping out of linear region
> -------------------------------------------------------------------------------
> 
> 
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