| Message ID | 20240611215801.443593152@goodmis.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v4,1/2] mm/memblock: Add "reserve_mem" to reserved named memory at boot up | expand |
On 6/11/24 14:56, Steven Rostedt wrote: > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > In order to allow for requesting a memory region that can be used for > things like pstore on multiple machines where the memory layout is not the > same, add a new option to the kernel command line called "reserve_mem". > > The format is: reserve_mem=nn:align:name > > Where it will find nn amount of memory at the given alignment of align. > The name field is to allow another subsystem to retrieve where the memory > was found. For example: > > reserve_mem=12M:4096:oops ramoops.mem_name=oops > > Where ramoops.mem_name will tell ramoops that memory was reserved for it > via the reserve_mem option and it can find it by calling: > > if (reserve_mem_find_by_name("oops", &start, &size)) { > // start holds the start address and size holds the size given > > This is typically used for systems that do not wipe the RAM, and this > command line will try to reserve the same physical memory on soft reboots. > Note, it is not guaranteed to be the same location. For example, if KASLR > places the kernel at the location of where the RAM reservation was from a > previous boot, the new reservation will be at a different location. Any > subsystem using this feature must add a way to verify that the contents of > the physical memory is from a previous boot, as there may be cases where > the memory will not be located at the same location. > > Not all systems may work either. There could be bit flips if the reboot > goes through the BIOS. Using kexec to reboot the machine is likely to > have better results in such cases. > > Link: https://lore.kernel.org/all/ZjJVnZUX3NZiGW6q@kernel.org/ > > Suggested-by: Mike Rapoport <rppt@kernel.org> > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > --- > Changes since v3: https://lore.kernel.org/linux-trace-kernel/20240606150316.751642266@goodmis.org > > - Changed table type of start and size from unsigned long to phys_addr_t > (as well as the parameters to the functions that use them) > > - Changed old reference to "early_reserve_mem" to "reserve_mem" > > - Check before reservering memory: > o Size is non-zero > o name has text in it > > - If align is less than SMP_CACHE_BYTES, make it SMP_CACHE_BYTES > > - Remove the silly check of testing *p == '\0' after a p += strlen(p) > > .../admin-guide/kernel-parameters.txt | 20 +++ > include/linux/mm.h | 2 + > mm/memblock.c | 115 ++++++++++++++++++ > 3 files changed, 137 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index b600df82669d..ce7de8136f2f 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -5710,6 +5710,26 @@ > them. If <base> is less than 0x10000, the region > is assumed to be I/O ports; otherwise it is memory. > > + reserve_mem= [RAM] > + Format: nn[KNG]:<align>:<label> > + Reserve physical memory and label it with a name that > + other subsystems can use to access it. This is typically > + used for systems that do not wipe the RAM, and this command > + line will try to reserve the same physical memory on > + soft reboots. Note, it is not guaranteed to be the same > + location. For example, if KASLR places the kernel at the > + location of where the RAM reservation was from a previous > + boot, the new reservation will be at a different location. > + Any subsystem using this feature must add a way to verify > + that the contents of the physical memory is from a previous > + boot, as there may be cases where the memory will not be > + located at the same location. > + > + The format is size:align:label for example, to request > + 12 megabytes of 4096 alignment for ramoops: > + > + reserve_mem=12M:4096:oops ramoops.mem_name=oops > + > reservetop= [X86-32,EARLY] > Format: nn[KMG] > Reserves a hole at the top of the kernel virtual > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 9849dfda44d4..077fb589b88a 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -4263,4 +4263,6 @@ static inline bool pfn_is_unaccepted_memory(unsigned long pfn) > void vma_pgtable_walk_begin(struct vm_area_struct *vma); > void vma_pgtable_walk_end(struct vm_area_struct *vma); > > +int reserve_mem_find_by_name(const char *name, phys_addr_t *start, phys_addr_t *size); > + > #endif /* _LINUX_MM_H */ > diff --git a/mm/memblock.c b/mm/memblock.c > index d09136e040d3..044ddce8f085 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -2244,6 +2244,121 @@ void __init memblock_free_all(void) > totalram_pages_add(pages); > } > > +/* Keep a table to reserve named memory */ > +#define RESERVE_MEM_MAX_ENTRIES 8 > +#define RESERVE_MEM_NAME_SIZE 16 > +struct reserve_mem_table { > + char name[RESERVE_MEM_NAME_SIZE]; > + phys_addr_t start; > + phys_addr_t size; > +}; > +static struct reserve_mem_table reserved_mem_table[RESERVE_MEM_MAX_ENTRIES]; > +static int reserved_mem_count; > + > +/* Add wildcard region with a lookup name */ > +static int __init reserved_mem_add(phys_addr_t start, phys_addr_t size, > + const char *name) > +{ > + struct reserve_mem_table *map; > + > + if (!name || !name[0] || strlen(name) >= RESERVE_MEM_NAME_SIZE) > + return -EINVAL; > + I know I am picky, but name is never NULL, and strlen(name) is guaranteed to be > 0. Personally I'd suggest to check for strlen(name) >= RESERVE_MEM_NAME_SIZE together with !strlen(name) and drop the duplicate checks here (and, as side effect, avoid the pointless memory allocation if the name is invalid). > + if (reserved_mem_count >= RESERVE_MEM_MAX_ENTRIES) > + return -1; > + > + map = &reserved_mem_table[reserved_mem_count++]; > + map->start = start; > + map->size = size; > + strscpy(map->name, name); > + return 0; > +} > + > +/** > + * reserve_mem_find_by_name - Find reserved memory region with a given name > + * @name: The name that is attached to a reserved memory region > + * @start: If found, holds the start address > + * @size: If found, holds the size of the address. > + * > + * Returns: 1 if found or 0 if not found. > + */ > +int reserve_mem_find_by_name(const char *name, phys_addr_t *start, phys_addr_t *size) > +{ > + struct reserve_mem_table *map; > + int i; > + > + for (i = 0; i < reserved_mem_count; i++) { > + map = &reserved_mem_table[i]; > + if (!map->size) > + continue; > + if (strcmp(name, map->name) == 0) { > + *start = map->start; > + *size = map->size; > + return 1; > + } > + } > + return 0; > +} > +EXPORT_SYMBOL_GPL(reserve_mem_find_by_name); > + > +/* > + * Parse reserve_mem=nn:align:name > + */ > +static int __init reserve_mem(char *p) > +{ > + phys_addr_t start, size, align; > + char *name; > + char *oldp; > + int err; > + > + if (!p) > + return -EINVAL; > + > + oldp = p; > + size = memparse(p, &p); > + if (!size || p == oldp) > + return -EINVAL; > + > + if (*p != ':') > + return -EINVAL; > + > + align = memparse(p+1, &p); > + if (*p != ':') > + return -EINVAL; > + > + /* > + * memblock_phys_alloc() doesn't like a zero size align, > + * but it is OK for this command to have it. > + */ > + if (align <= SMP_CACHE_BYTES) Any reason for using <= instead of < ? Guenter > + align = SMP_CACHE_BYTES; > + > + name = p + 1; > + if (!strlen(name)) > + return -EINVAL; > + > + /* Make sure that name has text */ > + for (p = name; *p; p++) { > + if (!isspace(*p)) > + break; > + } > + if (!*p) > + return -EINVAL; > + > + start = memblock_phys_alloc(size, align); > + if (!start) > + return -ENOMEM; > + > + err = reserved_mem_add(start, size, name); > + if (err) { > + memblock_phys_free(start, size); > + return err; > + } > + > + return 0; > +} > +__setup("reserve_mem=", reserve_mem); > + > #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_ARCH_KEEP_MEMBLOCK) > static const char * const flagname[] = { > [ilog2(MEMBLOCK_HOTPLUG)] = "HOTPLUG",
On Tue, 11 Jun 2024 15:26:05 -0700 Guenter Roeck <linux@roeck-us.net> wrote: > > diff --git a/mm/memblock.c b/mm/memblock.c > > index d09136e040d3..044ddce8f085 100644 > > --- a/mm/memblock.c > > +++ b/mm/memblock.c > > @@ -2244,6 +2244,121 @@ void __init memblock_free_all(void) > > totalram_pages_add(pages); > > } > > > > +/* Keep a table to reserve named memory */ > > +#define RESERVE_MEM_MAX_ENTRIES 8 > > +#define RESERVE_MEM_NAME_SIZE 16 > > +struct reserve_mem_table { > > + char name[RESERVE_MEM_NAME_SIZE]; > > + phys_addr_t start; > > + phys_addr_t size; > > +}; > > +static struct reserve_mem_table reserved_mem_table[RESERVE_MEM_MAX_ENTRIES]; > > +static int reserved_mem_count; > > + > > +/* Add wildcard region with a lookup name */ > > +static int __init reserved_mem_add(phys_addr_t start, phys_addr_t size, > > + const char *name) > > +{ > > + struct reserve_mem_table *map; > > + > > + if (!name || !name[0] || strlen(name) >= RESERVE_MEM_NAME_SIZE) > > + return -EINVAL; > > + > > I know I am picky, but name is never NULL, and strlen(name) is guaranteed to be > 0. > Personally I'd suggest to check for strlen(name) >= RESERVE_MEM_NAME_SIZE together > with !strlen(name) and drop the duplicate checks here (and, as side effect, avoid > the pointless memory allocation if the name is invalid). Yeah, it's now checked before hand. I'll remove it for v5. > > > + if (reserved_mem_count >= RESERVE_MEM_MAX_ENTRIES) > > + return -1; > > + > > + map = &reserved_mem_table[reserved_mem_count++]; > > + map->start = start; > > + map->size = size; > > + strscpy(map->name, name); > > + return 0; > > +} > > + > > +/* > > + * Parse reserve_mem=nn:align:name > > + */ > > +static int __init reserve_mem(char *p) > > +{ > > + phys_addr_t start, size, align; > > + char *name; > > + char *oldp; > > + int err; > > + > > + if (!p) > > + return -EINVAL; > > + > > + oldp = p; > > + size = memparse(p, &p); > > + if (!size || p == oldp) > > + return -EINVAL; > > + > > + if (*p != ':') > > + return -EINVAL; > > + > > + align = memparse(p+1, &p); > > + if (*p != ':') > > + return -EINVAL; > > + > > + /* > > + * memblock_phys_alloc() doesn't like a zero size align, > > + * but it is OK for this command to have it. > > + */ > > + if (align <= SMP_CACHE_BYTES) > > Any reason for using <= instead of < ? Nope. Not sure why I did that. :-/ I'll fix that too. Thanks, -- Steve > > Guenter > > > + align = SMP_CACHE_BYTES; > > + > > + name = p + 1; > > + if (!strlen(name)) > > + return -EINVAL; > > + > > + /* Make sure that name has text */ > > + for (p = name; *p; p++) { > > + if (!isspace(*p)) > > + break; > > + } > > + if (!*p) > > + return -EINVAL; > > + > > + start = memblock_phys_alloc(size, align); > > + if (!start) > > + return -ENOMEM; > > + > > + err = reserved_mem_add(start, size, name); > > + if (err) { > > + memblock_phys_free(start, size); > > + return err; > > + } > > + > > + return 0; > > +} > > +__setup("reserve_mem=", reserve_mem); > > + > > #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_ARCH_KEEP_MEMBLOCK) > > static const char * const flagname[] = { > > [ilog2(MEMBLOCK_HOTPLUG)] = "HOTPLUG",
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index b600df82669d..ce7de8136f2f 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5710,6 +5710,26 @@ them. If <base> is less than 0x10000, the region is assumed to be I/O ports; otherwise it is memory. + reserve_mem= [RAM] + Format: nn[KNG]:<align>:<label> + Reserve physical memory and label it with a name that + other subsystems can use to access it. This is typically + used for systems that do not wipe the RAM, and this command + line will try to reserve the same physical memory on + soft reboots. Note, it is not guaranteed to be the same + location. For example, if KASLR places the kernel at the + location of where the RAM reservation was from a previous + boot, the new reservation will be at a different location. + Any subsystem using this feature must add a way to verify + that the contents of the physical memory is from a previous + boot, as there may be cases where the memory will not be + located at the same location. + + The format is size:align:label for example, to request + 12 megabytes of 4096 alignment for ramoops: + + reserve_mem=12M:4096:oops ramoops.mem_name=oops + reservetop= [X86-32,EARLY] Format: nn[KMG] Reserves a hole at the top of the kernel virtual diff --git a/include/linux/mm.h b/include/linux/mm.h index 9849dfda44d4..077fb589b88a 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4263,4 +4263,6 @@ static inline bool pfn_is_unaccepted_memory(unsigned long pfn) void vma_pgtable_walk_begin(struct vm_area_struct *vma); void vma_pgtable_walk_end(struct vm_area_struct *vma); +int reserve_mem_find_by_name(const char *name, phys_addr_t *start, phys_addr_t *size); + #endif /* _LINUX_MM_H */ diff --git a/mm/memblock.c b/mm/memblock.c index d09136e040d3..044ddce8f085 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -2244,6 +2244,121 @@ void __init memblock_free_all(void) totalram_pages_add(pages); } +/* Keep a table to reserve named memory */ +#define RESERVE_MEM_MAX_ENTRIES 8 +#define RESERVE_MEM_NAME_SIZE 16 +struct reserve_mem_table { + char name[RESERVE_MEM_NAME_SIZE]; + phys_addr_t start; + phys_addr_t size; +}; +static struct reserve_mem_table reserved_mem_table[RESERVE_MEM_MAX_ENTRIES]; +static int reserved_mem_count; + +/* Add wildcard region with a lookup name */ +static int __init reserved_mem_add(phys_addr_t start, phys_addr_t size, + const char *name) +{ + struct reserve_mem_table *map; + + if (!name || !name[0] || strlen(name) >= RESERVE_MEM_NAME_SIZE) + return -EINVAL; + + if (reserved_mem_count >= RESERVE_MEM_MAX_ENTRIES) + return -1; + + map = &reserved_mem_table[reserved_mem_count++]; + map->start = start; + map->size = size; + strscpy(map->name, name); + return 0; +} + +/** + * reserve_mem_find_by_name - Find reserved memory region with a given name + * @name: The name that is attached to a reserved memory region + * @start: If found, holds the start address + * @size: If found, holds the size of the address. + * + * Returns: 1 if found or 0 if not found. + */ +int reserve_mem_find_by_name(const char *name, phys_addr_t *start, phys_addr_t *size) +{ + struct reserve_mem_table *map; + int i; + + for (i = 0; i < reserved_mem_count; i++) { + map = &reserved_mem_table[i]; + if (!map->size) + continue; + if (strcmp(name, map->name) == 0) { + *start = map->start; + *size = map->size; + return 1; + } + } + return 0; +} +EXPORT_SYMBOL_GPL(reserve_mem_find_by_name); + +/* + * Parse reserve_mem=nn:align:name + */ +static int __init reserve_mem(char *p) +{ + phys_addr_t start, size, align; + char *name; + char *oldp; + int err; + + if (!p) + return -EINVAL; + + oldp = p; + size = memparse(p, &p); + if (!size || p == oldp) + return -EINVAL; + + if (*p != ':') + return -EINVAL; + + align = memparse(p+1, &p); + if (*p != ':') + return -EINVAL; + + /* + * memblock_phys_alloc() doesn't like a zero size align, + * but it is OK for this command to have it. + */ + if (align <= SMP_CACHE_BYTES) + align = SMP_CACHE_BYTES; + + name = p + 1; + if (!strlen(name)) + return -EINVAL; + + /* Make sure that name has text */ + for (p = name; *p; p++) { + if (!isspace(*p)) + break; + } + if (!*p) + return -EINVAL; + + start = memblock_phys_alloc(size, align); + if (!start) + return -ENOMEM; + + err = reserved_mem_add(start, size, name); + if (err) { + memblock_phys_free(start, size); + return err; + } + + return 0; +} +__setup("reserve_mem=", reserve_mem); + #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_ARCH_KEEP_MEMBLOCK) static const char * const flagname[] = { [ilog2(MEMBLOCK_HOTPLUG)] = "HOTPLUG",