diff options
| -rw-r--r-- | Documentation/powerpc/firmware-assisted-dump.txt | 17 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/fadump.h | 5 | ||||
| -rw-r--r-- | arch/powerpc/kernel/fadump.c | 97 |
3 files changed, 108 insertions, 11 deletions
diff --git a/Documentation/powerpc/firmware-assisted-dump.txt b/Documentation/powerpc/firmware-assisted-dump.txt index bdd344aa18d9..18c5feef2577 100644 --- a/Documentation/powerpc/firmware-assisted-dump.txt +++ b/Documentation/powerpc/firmware-assisted-dump.txt @@ -113,7 +113,15 @@ header, is usually reserved at an offset greater than boot memory size (see Fig. 1). This area is *not* released: this region will be kept permanently reserved, so that it can act as a receptacle for a copy of the boot memory content in addition to CPU state -and HPTE region, in the case a crash does occur. +and HPTE region, in the case a crash does occur. Since this reserved +memory area is used only after the system crash, there is no point in +blocking this significant chunk of memory from production kernel. +Hence, the implementation uses the Linux kernel's Contiguous Memory +Allocator (CMA) for memory reservation if CMA is configured for kernel. +With CMA reservation this memory will be available for applications to +use it, while kernel is prevented from using it. With this fadump will +still be able to capture all of the kernel memory and most of the user +space memory except the user pages that were present in CMA region. o Memory Reservation during first kernel @@ -162,6 +170,9 @@ How to enable firmware-assisted dump (fadump): 1. Set config option CONFIG_FA_DUMP=y and build kernel. 2. Boot into linux kernel with 'fadump=on' kernel cmdline option. + By default, fadump reserved memory will be initialized as CMA area. + Alternatively, user can boot linux kernel with 'fadump=nocma' to + prevent fadump to use CMA. 3. Optionally, user can also set 'crashkernel=' kernel cmdline to specify size of the memory to reserve for boot memory dump preservation. @@ -172,6 +183,10 @@ NOTE: 1. 'fadump_reserve_mem=' parameter has been deprecated. Instead 2. If firmware-assisted dump fails to reserve memory then it will fallback to existing kdump mechanism if 'crashkernel=' option is set at kernel cmdline. + 3. if user wants to capture all of user space memory and ok with + reserved memory not available to production system, then + 'fadump=nocma' kernel parameter can be used to fallback to + old behaviour. Sysfs/debugfs files: ------------ diff --git a/arch/powerpc/include/asm/fadump.h b/arch/powerpc/include/asm/fadump.h index 1e7a33592e29..0a4e37159276 100644 --- a/arch/powerpc/include/asm/fadump.h +++ b/arch/powerpc/include/asm/fadump.h @@ -48,6 +48,10 @@ #define memblock_num_regions(memblock_type) (memblock.memblock_type.cnt) +/* Alignement per CMA requirement. */ +#define FADUMP_CMA_ALIGNMENT (PAGE_SIZE << \ + max_t(unsigned long, MAX_ORDER - 1, pageblock_order)) + /* Firmware provided dump sections */ #define FADUMP_CPU_STATE_DATA 0x0001 #define FADUMP_HPTE_REGION 0x0002 @@ -141,6 +145,7 @@ struct fw_dump { unsigned long fadump_supported:1; unsigned long dump_active:1; unsigned long dump_registered:1; + unsigned long nocma:1; }; /* diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c index 7a0da83bf883..ec937c7deae8 100644 --- a/arch/powerpc/kernel/fadump.c +++ b/arch/powerpc/kernel/fadump.c @@ -35,6 +35,7 @@ #include <linux/kobject.h> #include <linux/sysfs.h> #include <linux/slab.h> +#include <linux/cma.h> #include <asm/debugfs.h> #include <asm/page.h> @@ -46,6 +47,9 @@ static struct fw_dump fw_dump; static struct fadump_mem_struct fdm; static const struct fadump_mem_struct *fdm_active; +#ifdef CONFIG_CMA +static struct cma *fadump_cma; +#endif static DEFINE_MUTEX(fadump_mutex); struct fad_crash_memory_ranges *crash_memory_ranges; @@ -53,6 +57,67 @@ int crash_memory_ranges_size; int crash_mem_ranges; int max_crash_mem_ranges; +#ifdef CONFIG_CMA +/* + * fadump_cma_init() - Initialize CMA area from a fadump reserved memory + * + * This function initializes CMA area from fadump reserved memory. + * The total size of fadump reserved memory covers for boot memory size + * + cpu data size + hpte size and metadata. + * Initialize only the area equivalent to boot memory size for CMA use. + * The reamining portion of fadump reserved memory will be not given + * to CMA and pages for thoes will stay reserved. boot memory size is + * aligned per CMA requirement to satisy cma_init_reserved_mem() call. + * But for some reason even if it fails we still have the memory reservation + * with us and we can still continue doing fadump. + */ +int __init fadump_cma_init(void) +{ + unsigned long long base, size; + int rc; + + if (!fw_dump.fadump_enabled) + return 0; + + /* + * Do not use CMA if user has provided fadump=nocma kernel parameter. + * Return 1 to continue with fadump old behaviour. + */ + if (fw_dump.nocma) + return 1; + + base = fw_dump.reserve_dump_area_start; + size = fw_dump.boot_memory_size; + + if (!size) + return 0; + + rc = cma_init_reserved_mem(base, size, 0, "fadump_cma", &fadump_cma); + if (rc) { + pr_err("Failed to init cma area for firmware-assisted dump,%d\n", rc); + /* + * Though the CMA init has failed we still have memory + * reservation with us. The reserved memory will be + * blocked from production system usage. Hence return 1, + * so that we can continue with fadump. + */ + return 1; + } + + /* + * So we now have successfully initialized cma area for fadump. + */ + pr_info("Initialized 0x%lx bytes cma area at %ldMB from 0x%lx " + "bytes of memory reserved for firmware-assisted dump\n", + cma_get_size(fadump_cma), + (unsigned long)cma_get_base(fadump_cma) >> 20, + fw_dump.reserve_dump_area_size); + return 1; +} +#else +static int __init fadump_cma_init(void) { return 1; } +#endif /* CONFIG_CMA */ + /* Scan the Firmware Assisted dump configuration details. */ int __init early_init_dt_scan_fw_dump(unsigned long node, const char *uname, int depth, void *data) @@ -378,8 +443,15 @@ int __init fadump_reserve_mem(void) */ if (fdm_active) fw_dump.boot_memory_size = be64_to_cpu(fdm_active->rmr_region.source_len); - else + else { fw_dump.boot_memory_size = fadump_calculate_reserve_size(); +#ifdef CONFIG_CMA + if (!fw_dump.nocma) + fw_dump.boot_memory_size = + ALIGN(fw_dump.boot_memory_size, + FADUMP_CMA_ALIGNMENT); +#endif + } /* * Calculate the memory boundary. @@ -426,8 +498,9 @@ int __init fadump_reserve_mem(void) fw_dump.fadumphdr_addr = be64_to_cpu(fdm_active->rmr_region.destination_address) + be64_to_cpu(fdm_active->rmr_region.source_len); - pr_debug("fadumphdr_addr = %p\n", - (void *) fw_dump.fadumphdr_addr); + pr_debug("fadumphdr_addr = %pa\n", &fw_dump.fadumphdr_addr); + fw_dump.reserve_dump_area_start = base; + fw_dump.reserve_dump_area_size = size; } else { size = get_fadump_area_size(); @@ -455,10 +528,11 @@ int __init fadump_reserve_mem(void) (unsigned long)(size >> 20), (unsigned long)(base >> 20), (unsigned long)(memblock_phys_mem_size() >> 20)); - } - fw_dump.reserve_dump_area_start = base; - fw_dump.reserve_dump_area_size = size; + fw_dump.reserve_dump_area_start = base; + fw_dump.reserve_dump_area_size = size; + return fadump_cma_init(); + } return 1; } @@ -477,6 +551,10 @@ static int __init early_fadump_param(char *p) fw_dump.fadump_enabled = 1; else if (strncmp(p, "off", 3) == 0) fw_dump.fadump_enabled = 0; + else if (strncmp(p, "nocma", 5) == 0) { + fw_dump.fadump_enabled = 1; + fw_dump.nocma = 1; + } return 0; } @@ -1229,7 +1307,7 @@ static int fadump_unregister_dump(struct fadump_mem_struct *fdm) return 0; } -static int fadump_invalidate_dump(struct fadump_mem_struct *fdm) +static int fadump_invalidate_dump(const struct fadump_mem_struct *fdm) { int rc = 0; unsigned int wait_time; @@ -1260,9 +1338,8 @@ void fadump_cleanup(void) { /* Invalidate the registration only if dump is active. */ if (fw_dump.dump_active) { - init_fadump_mem_struct(&fdm, - be64_to_cpu(fdm_active->cpu_state_data.destination_address)); - fadump_invalidate_dump(&fdm); + /* pass the same memory dump structure provided by platform */ + fadump_invalidate_dump(fdm_active); } else if (fw_dump.dump_registered) { /* Un-register Firmware-assisted dump if it was registered. */ fadump_unregister_dump(&fdm); |