[PATCH v22 2/8] arm64: limit memory regions based on DT property, usable-memory-range
From: Dennis Chen <hidden>
Date: 2016-07-19 10:06:18
Also in:
kexec
Hello AKASHI, On Tue, Jul 19, 2016 at 05:35:55PM +0900, AKASHI Takahiro wrote:
James, On Mon, Jul 18, 2016 at 07:04:33PM +0100, James Morse wrote:quoted
Hi! (CC: Dennis Chen) On 12/07/16 06:05, AKASHI Takahiro wrote:quoted
Crash dump kernel will be run with a limited range of memory as System RAM. On arm64, we will use a device-tree property under /chosen, linux,usable-memory-range = <BASE SIZE> in order for primary kernel either on uefi or non-uefi (device tree only) system to hand over the information about usable memory region to crash dump kernel. This property will supercede entries in uefi memory map table and "memory" nodes in a device tree.quoted
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 51b1302..d8b296f 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c@@ -300,10 +300,48 @@ static int __init early_mem(char *p) } early_param("mem", early_mem); +static int __init early_init_dt_scan_usablemem(unsigned long node, + const char *uname, int depth, void *data) +{ + struct memblock_region *usablemem = (struct memblock_region *)data; + const __be32 *reg; + int len; + + usablemem->size = 0; + + if (depth != 1 || strcmp(uname, "chosen") != 0) + return 0; + + reg = of_get_flat_dt_prop(node, "linux,usable-memory-range", &len); + if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells))) + return 1; + + usablemem->base = dt_mem_next_cell(dt_root_addr_cells, ®); + usablemem->size = dt_mem_next_cell(dt_root_size_cells, ®); + + return 1; +} + +static void __init fdt_enforce_memory_region(void) +{ + struct memblock_region reg; + + of_scan_flat_dt(early_init_dt_scan_usablemem, ®); + + if (reg.size) { + memblock_remove(0, PAGE_ALIGN(reg.base)); + memblock_remove(round_down(reg.base + reg.size, PAGE_SIZE), + ULLONG_MAX);
According to the panic message from James, I guess the ACPI regions are out of the range [reg.base, reg.base + reg.size] and removed by your above codes. On ARM64, those ACPI regions have been added into memblock and marked as NOMAP, so I think it should be easy to adapt my fix to retain the NOMAP regions here Thanks, Dennis
quoted
I think this is a new way to trip the problem Dennis Chen has been working on [0]. If I kdump with --reuse-cmdline on a kernel booted with 'acpi=on', I get the panic below [1]...Yeah, it can be.quoted
It looks like Dennis's fix involves changes in mm/memblock.c, maybe they can be extended to support a range instead of just a limit? (It looks like x86 explicitly adds the acpi regions to the crash-kernels memory map in crash_setup_memmap_entries()). Is it possible for the kernel text to be outside this range? (a bug in kexec-tools, or another user of the DT property) If we haven't already failed in this case, it may be worth printing a warning, or refusing to restrict-memory/expose-vmcore.In my implementation of kdump, the usable memory for crash dump kernel will be allocated within memblock.memory after ACPI-related regions have been mapped. "linux,usable-memory-range" indicates this exact memory range. On crash dump kernel, my fdt_enforce_memory_region() in arm64_memblock_init() will exclude all the other regions from memblock.memory. So the kernel (with acpi=on) won't recognize ACPI-regions as normal memory, and map them by ioremap(). I thought that it was safe, but actually not due to unaligned accesses. As you suggested, we will probably be able to do the same thing of Chen's solution in fdt_enforce_memory_region(). Thanks, -Takahiro AKASHIquoted
Thanks, > > James [0] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-July/443356.html [1] [ 0.000000] efi: Getting EFI parameters from FDT: [ 0.000000] efi: EFI v2.50 by ARM Juno EFI Nov 24 2015 12:36:35 [ 0.000000] efi: ACPI=0xf95b0000 ACPI 2.0=0xf95b0014 PROP=0xfe8db4d8 [ 0.000000] Reserving 1KB of memory at 0x9fffff000 for elfcorehdr [ 0.000000] cma: Reserved 16 MiB at 0x00000009fec00000 [ 0.000000] ACPI: Early table checksum verification disabled [ 0.000000] ACPI: RSDP 0x00000000F95B0014 000024 (v02 ARMLTD) [ 0.000000] ACPI: XSDT 0x00000000F95A00E8 00004C (v01 ARMLTD ARM-JUNO 2014072 7 01000013) [ 0.000000] ACPI: FACP 0x00000000F9500000 00010C (v05 ARMLTD ARM-JUNO 2014072 7 ARM 00000099) [ 0.000000] ACPI: DSDT 0x00000000F94C0000 000396 (v01 ARMLTD ARM-JUNO 2014072 7 INTL 20150619) [ 0.000000] ACPI: GTDT 0x00000000F94F0000 000060 (v02 ARMLTD ARM-JUNO 2014072 7 ARM 00000099) [ 0.000000] ACPI: APIC 0x00000000F94E0000 000224 (v03 ARMLTD ARM-JUNO 2014072 7 ARM 00000099) [ 0.000000] ACPI: SSDT 0x00000000F94D0000 0001E3 (v01 ARMLTD ARM-JUNO 2014072 7 INTL 20150619) [ 0.000000] ACPI: MCFG 0x00000000F94B0000 00003C (v01 ARMLTD ARM-JUNO 2014072 7 ARM 00000099) ... [ 0.737577] Serial: AMBA PL011 UART driver [ 0.786086] HugeTLB registered 2 MB page size, pre-allocated 0 pages [ 0.794203] ACPI: Added _OSI(Module Device) [ 0.798659] ACPI: Added _OSI(Processor Device) [ 0.803190] ACPI: Added _OSI(3.0 _SCP Extensions) [ 0.807973] ACPI: Added _OSI(Processor Aggregator Device) [ 0.813653] Unable to handle kernel paging request at virtual address ffff000 00804e027 [ 0.821704] pgd = ffff000008cce000 [ 0.825155] [ffff00000804e027] *pgd=00000009ffffd003, *pud=00000009ffffc003, *pmd=00000009ffffb003, *pte=00e80000f94c0707 [ 0.836319] Internal error: Oops: 96000021 [#1] PREEMPT SMP [ 0.841972] Modules linked in: [ 0.845073] CPU: 2 PID: 1 Comm: swapper/0 Tainted: G S 4.7.0-rc4 + #4569 [ 0.852927] Hardware name: ARM Juno development board (r1) (DT) [ 0.858936] task: ffff80003d898000 ti: ffff80003d894000 task.ti: ffff80003d89 4000 [ 0.866537] PC is at acpi_ns_lookup+0x23c/0x378 [ 0.871131] LR is at acpi_ds_load1_begin_op+0x88/0x260 [ 0.876340] pc : [<ffff0000084061a4>] lr : [<ffff0000083fc08c>] pstate: 60000 045 [ 0.883846] sp : ffff80003d8979b0 [ 0.887206] x29: ffff80003d8979b0 x28: 0000000000000000 [ 0.892596] x27: 000000000000001b x26: ffff000008a80a07 [ 0.897986] x25: ffff80003d897a48 x24: 0000000000000001 [ 0.903377] x23: 0000000000000001 x22: ffff00000804e027 [ 0.908769] x21: 000000000000001b x20: 0000000000000001 [ 0.914158] x19: 0000000000000000 x18: ffff00000804efff [ 0.919547] x17: 00000000000038ff x16: 0000000000000002 [ 0.924937] x15: ffff00000804efff x14: 0000008000000000 [ 0.930326] x13: ffff000008c942b2 x12: ffff00000804efff [ 0.935717] x11: ffff000008bf0000 x10: 00000000ffffff76 [ 0.941107] x9 : 0000000000000000 x8 : ffff000008cb6000 [ 0.946498] x7 : 0000000000000000 x6 : ffff80003d897aa8 [ 0.951891] x5 : ffff80003d028400 x4 : 0000000000000001 [ 0.957281] x3 : 0000000000000003 x2 : ffff000008cb6090 [ 0.962673] x1 : 000000000000005f x0 : 0000000000000000 [ 0.968063] [ 0.969569] Process swapper/0 (pid: 1, stack limit = 0xffff80003d894020) [ 1.387661] Call trace: ... [ 1.473172] [<ffff0000084061a4>] acpi_ns_lookup+0x23c/0x378 [ 1.478832] [<ffff0000083fc08c>] acpi_ds_load1_begin_op+0x88/0x260 [ 1.485105] [<ffff00000840c0e8>] acpi_ps_build_named_op+0xa8/0x170 [ 1.491378] [<ffff00000840c2e0>] acpi_ps_create_op+0x130/0x230 [ 1.497299] [<ffff00000840bc28>] acpi_ps_parse_loop+0x168/0x580 [ 1.503302] [<ffff00000840cb44>] acpi_ps_parse_aml+0xa0/0x278 [ 1.509135] [<ffff0000084081d0>] acpi_ns_one_complete_parse+0x128/0x150 [ 1.515852] [<ffff00000840821c>] acpi_ns_parse_table+0x24/0x44 [ 1.521775] [<ffff0000084079e8>] acpi_ns_load_table+0x54/0xdc [ 1.527612] [<ffff000008411038>] acpi_tb_load_namespace+0xd0/0x230 [ 1.533887] [<ffff000008b2695c>] acpi_load_tables+0x3c/0xa8 [ 1.539542] [<ffff000008b25974>] acpi_init+0x88/0x2b0 [ 1.544670] [<ffff000008081a08>] do_one_initcall+0x38/0x128 [ 1.550325] [<ffff000008b00cc0>] kernel_init_freeable+0x14c/0x1f0 [ 1.556517] [<ffff0000087d2088>] kernel_init+0x10/0x100 [ 1.561823] [<ffff000008084e10>] ret_from_fork+0x10/0x40 [ 1.567216] Code: b9008fbb 2a000318 36380054 32190318 (b94002c0) [ 1.573451] ---[ end trace dec6cecdcba673b7 ]--- [ 1.578158] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00 00000b [ 1.578158] [ 1.587428] SMP: stopping secondary CPUs [ 1.591411] ---[ end Kernel panic - not syncing: Attempted to kill init! exit code=0x0000000b [ 0.969225] Process swapper/0 (pid: 1, stack limit = 0xffff80003d894020)
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