From d4c4fed08f31f3746000c46cb1b20bed2959547a Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 15 Aug 2016 09:05:45 -0600 Subject: efi: Make for_each_efi_memory_desc_in_map() cope with running on Xen While commit 55f1ea15216 ("efi: Fix for_each_efi_memory_desc_in_map() for empty memmaps") made an attempt to deal with empty memory maps, it didn't address the case where the map field never gets set, as is apparently the case when running under Xen. Reported-by: Tested-by: Cc: Vitaly Kuznetsov Cc: Jiri Slaby Cc: Mark Rutland Cc: # v4.7+ Signed-off-by: Jan Beulich [ Guard the loop with a NULL check instead of pointer underflow ] Signed-off-by: Matt Fleming --- include/linux/efi.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/efi.h b/include/linux/efi.h index 7f5a582253853..23cd3ced8c1af 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -946,7 +946,7 @@ extern int efi_memattr_apply_permissions(struct mm_struct *mm, /* Iterate through an efi_memory_map */ #define for_each_efi_memory_desc_in_map(m, md) \ for ((md) = (m)->map; \ - ((void *)(md) + (m)->desc_size) <= (m)->map_end; \ + (md) && ((void *)(md) + (m)->desc_size) <= (m)->map_end; \ (md) = (void *)(md) + (m)->desc_size) /** -- cgit v1.2.3 From dadb57abc37499f565b23933dbf49b435c3ba8af Mon Sep 17 00:00:00 2001 From: Jeffrey Hugo Date: Mon, 29 Aug 2016 14:38:51 -0600 Subject: efi/libstub: Allocate headspace in efi_get_memory_map() efi_get_memory_map() allocates a buffer to store the memory map that it retrieves. This buffer may need to be reused by the client after ExitBootServices() is called, at which point allocations are not longer permitted. To support this usecase, provide the allocated buffer size back to the client, and allocate some additional headroom to account for any reasonable growth in the map that is likely to happen between the call to efi_get_memory_map() and the client reusing the buffer. Signed-off-by: Jeffrey Hugo Cc: Ard Biesheuvel Cc: Mark Rutland Cc: Leif Lindholm Cc: Ingo Molnar Cc: Signed-off-by: Matt Fleming --- arch/x86/boot/compressed/eboot.c | 20 ++++-- drivers/firmware/efi/libstub/efi-stub-helper.c | 96 ++++++++++++++++++-------- drivers/firmware/efi/libstub/fdt.c | 17 +++-- drivers/firmware/efi/libstub/random.c | 12 +++- include/linux/efi.h | 15 ++-- 5 files changed, 111 insertions(+), 49 deletions(-) (limited to 'include') diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c index ff574dad95cca..c5b7c7b4f0d75 100644 --- a/arch/x86/boot/compressed/eboot.c +++ b/arch/x86/boot/compressed/eboot.c @@ -1008,7 +1008,7 @@ static efi_status_t exit_boot(struct boot_params *boot_params, void *handle, bool is64) { struct efi_info *efi = &boot_params->efi_info; - unsigned long map_sz, key, desc_size; + unsigned long map_sz, key, desc_size, buff_size; efi_memory_desc_t *mem_map; struct setup_data *e820ext; const char *signature; @@ -1019,14 +1019,20 @@ static efi_status_t exit_boot(struct boot_params *boot_params, bool called_exit = false; u8 nr_entries; int i; - - nr_desc = 0; - e820ext = NULL; - e820ext_size = 0; + struct efi_boot_memmap map; + + nr_desc = 0; + e820ext = NULL; + e820ext_size = 0; + map.map = &mem_map; + map.map_size = &map_sz; + map.desc_size = &desc_size; + map.desc_ver = &desc_version; + map.key_ptr = &key; + map.buff_size = &buff_size; get_map: - status = efi_get_memory_map(sys_table, &mem_map, &map_sz, &desc_size, - &desc_version, &key); + status = efi_get_memory_map(sys_table, &map); if (status != EFI_SUCCESS) return status; diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c index 3bd127f953151..29368ac692213 100644 --- a/drivers/firmware/efi/libstub/efi-stub-helper.c +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c @@ -41,6 +41,8 @@ static unsigned long __chunk_size = EFI_READ_CHUNK_SIZE; #define EFI_ALLOC_ALIGN EFI_PAGE_SIZE #endif +#define EFI_MMAP_NR_SLACK_SLOTS 8 + struct file_info { efi_file_handle_t *handle; u64 size; @@ -63,49 +65,62 @@ void efi_printk(efi_system_table_t *sys_table_arg, char *str) } } +static inline bool mmap_has_headroom(unsigned long buff_size, + unsigned long map_size, + unsigned long desc_size) +{ + unsigned long slack = buff_size - map_size; + + return slack / desc_size >= EFI_MMAP_NR_SLACK_SLOTS; +} + efi_status_t efi_get_memory_map(efi_system_table_t *sys_table_arg, - efi_memory_desc_t **map, - unsigned long *map_size, - unsigned long *desc_size, - u32 *desc_ver, - unsigned long *key_ptr) + struct efi_boot_memmap *map) { efi_memory_desc_t *m = NULL; efi_status_t status; unsigned long key; u32 desc_version; - *map_size = sizeof(*m) * 32; + *map->desc_size = sizeof(*m); + *map->map_size = *map->desc_size * 32; + *map->buff_size = *map->map_size; again: - /* - * Add an additional efi_memory_desc_t because we're doing an - * allocation which may be in a new descriptor region. - */ - *map_size += sizeof(*m); status = efi_call_early(allocate_pool, EFI_LOADER_DATA, - *map_size, (void **)&m); + *map->map_size, (void **)&m); if (status != EFI_SUCCESS) goto fail; - *desc_size = 0; + *map->desc_size = 0; key = 0; - status = efi_call_early(get_memory_map, map_size, m, - &key, desc_size, &desc_version); - if (status == EFI_BUFFER_TOO_SMALL) { + status = efi_call_early(get_memory_map, map->map_size, m, + &key, map->desc_size, &desc_version); + if (status == EFI_BUFFER_TOO_SMALL || + !mmap_has_headroom(*map->buff_size, *map->map_size, + *map->desc_size)) { efi_call_early(free_pool, m); + /* + * Make sure there is some entries of headroom so that the + * buffer can be reused for a new map after allocations are + * no longer permitted. Its unlikely that the map will grow to + * exceed this headroom once we are ready to trigger + * ExitBootServices() + */ + *map->map_size += *map->desc_size * EFI_MMAP_NR_SLACK_SLOTS; + *map->buff_size = *map->map_size; goto again; } if (status != EFI_SUCCESS) efi_call_early(free_pool, m); - if (key_ptr && status == EFI_SUCCESS) - *key_ptr = key; - if (desc_ver && status == EFI_SUCCESS) - *desc_ver = desc_version; + if (map->key_ptr && status == EFI_SUCCESS) + *map->key_ptr = key; + if (map->desc_ver && status == EFI_SUCCESS) + *map->desc_ver = desc_version; fail: - *map = m; + *map->map = m; return status; } @@ -113,13 +128,20 @@ fail: unsigned long get_dram_base(efi_system_table_t *sys_table_arg) { efi_status_t status; - unsigned long map_size; + unsigned long map_size, buff_size; unsigned long membase = EFI_ERROR; struct efi_memory_map map; efi_memory_desc_t *md; + struct efi_boot_memmap boot_map; - status = efi_get_memory_map(sys_table_arg, (efi_memory_desc_t **)&map.map, - &map_size, &map.desc_size, NULL, NULL); + boot_map.map = (efi_memory_desc_t **)&map.map; + boot_map.map_size = &map_size; + boot_map.desc_size = &map.desc_size; + boot_map.desc_ver = NULL; + boot_map.key_ptr = NULL; + boot_map.buff_size = &buff_size; + + status = efi_get_memory_map(sys_table_arg, &boot_map); if (status != EFI_SUCCESS) return membase; @@ -144,15 +166,22 @@ efi_status_t efi_high_alloc(efi_system_table_t *sys_table_arg, unsigned long size, unsigned long align, unsigned long *addr, unsigned long max) { - unsigned long map_size, desc_size; + unsigned long map_size, desc_size, buff_size; efi_memory_desc_t *map; efi_status_t status; unsigned long nr_pages; u64 max_addr = 0; int i; + struct efi_boot_memmap boot_map; + + boot_map.map = ↦ + boot_map.map_size = &map_size; + boot_map.desc_size = &desc_size; + boot_map.desc_ver = NULL; + boot_map.key_ptr = NULL; + boot_map.buff_size = &buff_size; - status = efi_get_memory_map(sys_table_arg, &map, &map_size, &desc_size, - NULL, NULL); + status = efi_get_memory_map(sys_table_arg, &boot_map); if (status != EFI_SUCCESS) goto fail; @@ -230,14 +259,21 @@ efi_status_t efi_low_alloc(efi_system_table_t *sys_table_arg, unsigned long size, unsigned long align, unsigned long *addr) { - unsigned long map_size, desc_size; + unsigned long map_size, desc_size, buff_size; efi_memory_desc_t *map; efi_status_t status; unsigned long nr_pages; int i; + struct efi_boot_memmap boot_map; + + boot_map.map = ↦ + boot_map.map_size = &map_size; + boot_map.desc_size = &desc_size; + boot_map.desc_ver = NULL; + boot_map.key_ptr = NULL; + boot_map.buff_size = &buff_size; - status = efi_get_memory_map(sys_table_arg, &map, &map_size, &desc_size, - NULL, NULL); + status = efi_get_memory_map(sys_table_arg, &boot_map); if (status != EFI_SUCCESS) goto fail; diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c index e58abfa953cc5..bec0fa8d87461 100644 --- a/drivers/firmware/efi/libstub/fdt.c +++ b/drivers/firmware/efi/libstub/fdt.c @@ -175,13 +175,21 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table, unsigned long fdt_addr, unsigned long fdt_size) { - unsigned long map_size, desc_size; + unsigned long map_size, desc_size, buff_size; u32 desc_ver; unsigned long mmap_key; efi_memory_desc_t *memory_map, *runtime_map; unsigned long new_fdt_size; efi_status_t status; int runtime_entry_count = 0; + struct efi_boot_memmap map; + + map.map = &runtime_map; + map.map_size = &map_size; + map.desc_size = &desc_size; + map.desc_ver = &desc_ver; + map.key_ptr = &mmap_key; + map.buff_size = &buff_size; /* * Get a copy of the current memory map that we will use to prepare @@ -189,8 +197,7 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table, * subsequent allocations adding entries, since they could not affect * the number of EFI_MEMORY_RUNTIME regions. */ - status = efi_get_memory_map(sys_table, &runtime_map, &map_size, - &desc_size, &desc_ver, &mmap_key); + status = efi_get_memory_map(sys_table, &map); if (status != EFI_SUCCESS) { pr_efi_err(sys_table, "Unable to retrieve UEFI memory map.\n"); return status; @@ -199,6 +206,7 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table, pr_efi(sys_table, "Exiting boot services and installing virtual address map...\n"); + map.map = &memory_map; /* * Estimate size of new FDT, and allocate memory for it. We * will allocate a bigger buffer if this ends up being too @@ -218,8 +226,7 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table, * we can get the memory map key needed for * exit_boot_services(). */ - status = efi_get_memory_map(sys_table, &memory_map, &map_size, - &desc_size, &desc_ver, &mmap_key); + status = efi_get_memory_map(sys_table, &map); if (status != EFI_SUCCESS) goto fail_free_new_fdt; diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c index 53f6d3fe6d862..0c9f58c5ba501 100644 --- a/drivers/firmware/efi/libstub/random.c +++ b/drivers/firmware/efi/libstub/random.c @@ -73,12 +73,20 @@ efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg, unsigned long random_seed) { unsigned long map_size, desc_size, total_slots = 0, target_slot; + unsigned long buff_size; efi_status_t status; efi_memory_desc_t *memory_map; int map_offset; + struct efi_boot_memmap map; - status = efi_get_memory_map(sys_table_arg, &memory_map, &map_size, - &desc_size, NULL, NULL); + map.map = &memory_map; + map.map_size = &map_size; + map.desc_size = &desc_size; + map.desc_ver = NULL; + map.key_ptr = NULL; + map.buff_size = &buff_size; + + status = efi_get_memory_map(sys_table_arg, &map); if (status != EFI_SUCCESS) return status; diff --git a/include/linux/efi.h b/include/linux/efi.h index 23cd3ced8c1af..943fee5241761 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -118,6 +118,15 @@ typedef struct { u32 imagesize; } efi_capsule_header_t; +struct efi_boot_memmap { + efi_memory_desc_t **map; + unsigned long *map_size; + unsigned long *desc_size; + u32 *desc_ver; + unsigned long *key_ptr; + unsigned long *buff_size; +}; + /* * EFI capsule flags */ @@ -1371,11 +1380,7 @@ char *efi_convert_cmdline(efi_system_table_t *sys_table_arg, efi_loaded_image_t *image, int *cmd_line_len); efi_status_t efi_get_memory_map(efi_system_table_t *sys_table_arg, - efi_memory_desc_t **map, - unsigned long *map_size, - unsigned long *desc_size, - u32 *desc_ver, - unsigned long *key_ptr); + struct efi_boot_memmap *map); efi_status_t efi_low_alloc(efi_system_table_t *sys_table_arg, unsigned long size, unsigned long align, -- cgit v1.2.3 From fc07716ba803483be91bc4b2344f9c84985e6f07 Mon Sep 17 00:00:00 2001 From: Jeffrey Hugo Date: Mon, 29 Aug 2016 14:38:52 -0600 Subject: efi/libstub: Introduce ExitBootServices helper The spec allows ExitBootServices to fail with EFI_INVALID_PARAMETER if a race condition has occurred where the EFI has updated the memory map after the stub grabbed a reference to the map. The spec defines a retry proceedure with specific requirements to handle this scenario. This scenario was previously observed on x86 - commit d3768d885c6c ("x86, efi: retry ExitBootServices() on failure") but the current fix is not spec compliant and the scenario is now observed on the Qualcomm Technologies QDF2432 via the FDT stub which does not handle the error and thus causes boot failures. The user will notice the boot failure as the kernel is not executed and the system may drop back to a UEFI shell, but will be unresponsive to input and the system will require a power cycle to recover. Add a helper to the stub library that correctly adheres to the spec in the case of EFI_INVALID_PARAMETER from ExitBootServices and can be universally used across all stub implementations. Signed-off-by: Jeffrey Hugo Cc: Ard Biesheuvel Cc: Mark Rutland Cc: Leif Lindholm Cc: Ingo Molnar Cc: Signed-off-by: Matt Fleming --- drivers/firmware/efi/libstub/efi-stub-helper.c | 73 ++++++++++++++++++++++++++ include/linux/efi.h | 10 ++++ 2 files changed, 83 insertions(+) (limited to 'include') diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c index 29368ac692213..aded106620204 100644 --- a/drivers/firmware/efi/libstub/efi-stub-helper.c +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c @@ -740,3 +740,76 @@ char *efi_convert_cmdline(efi_system_table_t *sys_table_arg, *cmd_line_len = options_bytes; return (char *)cmdline_addr; } + +/* + * Handle calling ExitBootServices according to the requirements set out by the + * spec. Obtains the current memory map, and returns that info after calling + * ExitBootServices. The client must specify a function to perform any + * processing of the memory map data prior to ExitBootServices. A client + * specific structure may be passed to the function via priv. The client + * function may be called multiple times. + */ +efi_status_t efi_exit_boot_services(efi_system_table_t *sys_table_arg, + void *handle, + struct efi_boot_memmap *map, + void *priv, + efi_exit_boot_map_processing priv_func) +{ + efi_status_t status; + + status = efi_get_memory_map(sys_table_arg, map); + + if (status != EFI_SUCCESS) + goto fail; + + status = priv_func(sys_table_arg, map, priv); + if (status != EFI_SUCCESS) + goto free_map; + + status = efi_call_early(exit_boot_services, handle, *map->key_ptr); + + if (status == EFI_INVALID_PARAMETER) { + /* + * The memory map changed between efi_get_memory_map() and + * exit_boot_services(). Per the UEFI Spec v2.6, Section 6.4: + * EFI_BOOT_SERVICES.ExitBootServices we need to get the + * updated map, and try again. The spec implies one retry + * should be sufficent, which is confirmed against the EDK2 + * implementation. Per the spec, we can only invoke + * get_memory_map() and exit_boot_services() - we cannot alloc + * so efi_get_memory_map() cannot be used, and we must reuse + * the buffer. For all practical purposes, the headroom in the + * buffer should account for any changes in the map so the call + * to get_memory_map() is expected to succeed here. + */ + *map->map_size = *map->buff_size; + status = efi_call_early(get_memory_map, + map->map_size, + *map->map, + map->key_ptr, + map->desc_size, + map->desc_ver); + + /* exit_boot_services() was called, thus cannot free */ + if (status != EFI_SUCCESS) + goto fail; + + status = priv_func(sys_table_arg, map, priv); + /* exit_boot_services() was called, thus cannot free */ + if (status != EFI_SUCCESS) + goto fail; + + status = efi_call_early(exit_boot_services, handle, *map->key_ptr); + } + + /* exit_boot_services() was called, thus cannot free */ + if (status != EFI_SUCCESS) + goto fail; + + return EFI_SUCCESS; + +free_map: + efi_call_early(free_pool, *map->map); +fail: + return status; +} diff --git a/include/linux/efi.h b/include/linux/efi.h index 943fee5241761..0148a3046b486 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1462,4 +1462,14 @@ extern void efi_call_virt_check_flags(unsigned long flags, const char *call); arch_efi_call_virt_teardown(); \ }) +typedef efi_status_t (*efi_exit_boot_map_processing)( + efi_system_table_t *sys_table_arg, + struct efi_boot_memmap *map, + void *priv); + +efi_status_t efi_exit_boot_services(efi_system_table_t *sys_table, + void *handle, + struct efi_boot_memmap *map, + void *priv, + efi_exit_boot_map_processing priv_func); #endif /* _LINUX_EFI_H */ -- cgit v1.2.3