arm64:acpi fix the acpi alignment exception when 'mem=' specified

When kernel parameter 'mem=x' is specified by the command line,
probably the ACPI memory regions from firmware will beyond the
scope of the physical memory space after limited, if we don't add
back those regions into memblock in this case, then the ACPI core
will map it as device memory type. Since the ACPI core will produce
non-alignment access when parsing the AML data stream, alignment
exception will be generated upon the device memory mapped region.

Below is an alignment exception output observed on ARM platform
with acpi enabled:
...
[    0.542475] Unable to handle kernel paging request at virtual address ffff0000080521e7
[    0.550457] pgd = ffff000008aa0000
[    0.553880] [ffff0000080521e7] *pgd=000000801fffe003, *pud=000000801fffd003, *pmd=000000801fffc003, *pte=00e80083ff1c1707
[    0.564939] Internal error: Oops: 96000021 [#1] PREEMPT SMP
[    0.570553] Modules linked in:
[    0.573626] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.7.0-rc3-next-20160616+ torvalds#172
[    0.581344] Hardware name: AMD Overdrive/Supercharger/Default string, BIOS ROD1001A 02/09/2016
[    0.590025] task: ffff800001ef0000 ti: ffff800001ef8000 task.ti: ffff800001ef8000
[    0.597571] PC is at acpi_ns_lookup+0x520/0x734
[    0.602134] LR is at acpi_ns_lookup+0x4a4/0x734
[    0.606693] pc : [<ffff0000083b8b10>] lr : [<ffff0000083b8a94>] pstate: 60000045
[    0.614145] sp : ffff800001efb8b0
[    0.617478] x29: ffff800001efb8c0 x28: 000000000000001b
[    0.622829] x27: 0000000000000001 x26: 0000000000000000
[    0.628181] x25: ffff800001efb9e8 x24: ffff000008a10000
[    0.633531] x23: 0000000000000001 x22: 0000000000000001
[    0.638881] x21: ffff000008724000 x20: 000000000000001b
[    0.644230] x19: ffff0000080521e7 x18: 000000000000000d
[    0.649580] x17: 00000000000038ff x16: 0000000000000002
[    0.654929] x15: 0000000000000007 x14: 0000000000007fff
[    0.660278] x13: ffffff0000000000 x12: 0000000000000018
[    0.665627] x11: 000000001fffd200 x10: 00000000ffffff76
[    0.670978] x9 : 000000000000005f x8 : ffff000008725fa8
[    0.676328] x7 : ffff000008a8df70 x6 : ffff000008a8df70
[    0.681679] x5 : ffff000008a8d000 x4 : 0000000000000010
[    0.687027] x3 : 0000000000000010 x2 : 000000000000000c
[    0.692378] x1 : 0000000000000006 x0 : 0000000000000000
...
[    1.262235] [<ffff0000083b8b10>] acpi_ns_lookup+0x520/0x734
[    1.267845] [<ffff0000083a7160>] acpi_ds_load1_begin_op+0x174/0x4fc
[    1.274156] [<ffff0000083c1f4c>] acpi_ps_build_named_op+0xf8/0x220
[    1.280380] [<ffff0000083c227c>] acpi_ps_create_op+0x208/0x33c
[    1.286254] [<ffff0000083c1820>] acpi_ps_parse_loop+0x204/0x838
[    1.292215] [<ffff0000083c2fd4>] acpi_ps_parse_aml+0x1bc/0x42c
[    1.298090] [<ffff0000083bc6e8>] acpi_ns_one_complete_parse+0x1e8/0x22c
[    1.304753] [<ffff0000083bc7b8>] acpi_ns_parse_table+0x8c/0x128
[    1.310716] [<ffff0000083bb8fc>] acpi_ns_load_table+0xc0/0x1e8
[    1.316591] [<ffff0000083c9068>] acpi_tb_load_namespace+0xf8/0x2e8
[    1.322818] [<ffff000008984128>] acpi_load_tables+0x7c/0x110
[    1.328516] [<ffff000008982ea4>] acpi_init+0x90/0x2c0
[    1.333603] [<ffff0000080819fc>] do_one_initcall+0x38/0x12c
[    1.339215] [<ffff000008960cd4>] kernel_init_freeable+0x148/0x1ec
[    1.345353] [<ffff0000086b7d30>] kernel_init+0x10/0xec
[    1.350529] [<ffff000008084e10>] ret_from_fork+0x10/0x40
[    1.355878] Code: b9009fbc 2a00037b 36380057 3219037b (b940026)
[    1.362035] ---[ end trace 03381e5eb0a24de4 ]---
[    1.366691] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b

With 'efi=debug', we can see those ACPI regions from firmware as:
[    0.000000] efi:   0x0083ff1b5000-0x0083ff1c2fff [ACPI Reclaim Memory|   |  |  |  |  |  |  |   |WB|WT|WC|UC]*
[    0.000000] efi:   0x0083ff223000-0x0083ff224fff [ACPI Memory NVS    |   |  |  |  |  |  |  |   |WB|WT|WC|UC]*

This patch is trying to add back those regions into memblock, make
ACPI core map it as normal memory instead of device memory type.

Signed-off-by: Dennis Chen <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Steve Capper <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Matt Fleming <[email protected]>
Cc: [email protected]
Cc: [email protected]

Author: arm64b

arch/arm64/include/asm/memblock.h

@@ -16,6 +16,18 @@
 #ifndef __ASM_MEMBLOCK_H
 #define __ASM_MEMBLOCK_H
 
-extern void arm64_memblock_init(void);
+#ifdef CONFIG_ACPI
+typedef struct {
+	u64 base;
+	u64 size;
+	int resv;
+} efi_acpi_reg_t;
+
+#define MAX_ACPI_REGS   4
+extern unsigned int nr_acpi_regs;
+extern efi_acpi_reg_t acpi_regs[MAX_ACPI_REGS];
+#endif
 
+extern void arm64_memblock_init(void);
+extern phys_addr_t memory_limit;
 #endif

arch/arm64/kernel/acpi.c

@@ -28,6 +28,7 @@
 #include <asm/cputype.h>
 #include <asm/cpu_ops.h>
 #include <asm/smp_plat.h>
+#include <asm/memblock.h>
 
 #ifdef CONFIG_ACPI_APEI
 # include <linux/efi.h>
@@ -196,6 +197,8 @@ static int __init acpi_fadt_sanity_check(void)
  */
 void __init acpi_boot_table_init(void)
 {
+	int i;
+
 	/*
 	 * Enable ACPI instead of device tree unless
 	 * - ACPI has been disabled explicitly (acpi=off), or
@@ -226,6 +229,26 @@ void __init acpi_boot_table_init(void)
 		if (!param_acpi_force)
 			disable_acpi();
 	}
+
+	/*
+	 * For the case of 'mem=x' kernel parameter specified by cmdline:
+	 * when ACPI parses raw AML data within the ACPI data region,
+	 * sometimes it will produce non-alignment memory access, in order
+	 * to make kernel avoid generating alignment fault in this case, we
+	 * need to add back the firmware ACPI memory region into memblock,
+	 * thus the ACPI core will map it as normal memory, otherwise ACPI
+	 * will map the region as device memory type which trigers alignment
+	 * exception.
+	 */
+	if (!acpi_disabled && memory_limit != (phys_addr_t)ULLONG_MAX) {
+		for (i = 0; i < nr_acpi_regs; i++) {
+			memblock_add(acpi_regs[i].base, acpi_regs[i].size);
+			/* MEMBLOCK_NOMAP maybe cleaned before, re-flag it */
+			if (acpi_regs[i].resv)
+				memblock_mark_nomap(acpi_regs[i].base,
+					acpi_regs[i].size);
+		}
+	}
 }
 
 #ifdef CONFIG_ACPI_APEI

arch/arm64/mm/init.c

@@ -46,6 +46,7 @@
 #include <asm/sizes.h>
 #include <asm/tlb.h>
 #include <asm/alternative.h>
+#include <asm/memblock.h>
 
 #include "mm.h"
 
@@ -172,7 +173,7 @@ static void __init arm64_memory_present(void)
 }
 #endif
 
-static phys_addr_t memory_limit = (phys_addr_t)ULLONG_MAX;
+phys_addr_t memory_limit = (phys_addr_t)ULLONG_MAX;
 
 /*
  * Limit the memory size that was specified via FDT.

drivers/firmware/efi/arm-init.c

@@ -23,9 +23,15 @@
 #include <linux/screen_info.h>
 
 #include <asm/efi.h>
+#include <asm/memblock.h>
 
 u64 efi_system_table;
 
+#ifdef CONFIG_ACPI
+unsigned int nr_acpi_regs;
+efi_acpi_reg_t acpi_regs[MAX_ACPI_REGS];
+#endif
+
 static int __init is_normal_ram(efi_memory_desc_t *md)
 {
 	if (md->attribute & EFI_MEMORY_WB)
@@ -210,6 +216,19 @@ static __init void reserve_regions(void)
 		if (resv)
 			memblock_mark_nomap(paddr, size);
 
+#ifdef CONFIG_ACPI
+		if (md->type == EFI_ACPI_RECLAIM_MEMORY ||
+			md->type == EFI_ACPI_MEMORY_NVS) {
+			if (nr_acpi_regs >= MAX_ACPI_REGS) {
+				WARN_ONCE(1, "Too many ACPI mem regions: %d\n", nr_acpi_regs);
+				continue;
+			}
+			acpi_regs[nr_acpi_regs].base = paddr;
+			acpi_regs[nr_acpi_regs].size = size;
+			acpi_regs[nr_acpi_regs].resv = resv;
+			nr_acpi_regs++;
+		}
+#endif
 	}
 
 	set_bit(EFI_MEMMAP, &efi.flags);