From a6e4d5a03e9e3587e88aba687d8f225f4f04c792 Mon Sep 17 00:00:00 2001 From: Matt Fleming Date: Mon, 25 Mar 2013 09:14:30 +0000 Subject: x86, efivars: firmware bug workarounds should be in platform code Let's not burden ia64 with checks in the common efivars code that we're not writing too much data to the variable store. That kind of thing is an x86 firmware bug, plain and simple. efi_query_variable_store() provides platforms with a wrapper in which they can perform checks and workarounds for EFI variable storage bugs. Cc: H. Peter Anvin Cc: Matthew Garrett Signed-off-by: Matt Fleming --- arch/x86/platform/efi/efi.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'arch/x86') diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 5f2ecaf3f9d..c89c245eff4 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -999,3 +999,28 @@ u64 efi_mem_attributes(unsigned long phys_addr) } return 0; } + +/* + * Some firmware has serious problems when using more than 50% of the EFI + * variable store, i.e. it triggers bugs that can brick machines. Ensure that + * we never use more than this safe limit. + * + * Return EFI_SUCCESS if it is safe to write 'size' bytes to the variable + * store. + */ +efi_status_t efi_query_variable_store(u32 attributes, unsigned long size) +{ + efi_status_t status; + u64 storage_size, remaining_size, max_size; + + status = efi.query_variable_info(attributes, &storage_size, + &remaining_size, &max_size); + if (status != EFI_SUCCESS) + return status; + + if (!storage_size || size > remaining_size || size > max_size || + (remaining_size - size) < (storage_size / 2)) + return EFI_OUT_OF_RESOURCES; + + return EFI_SUCCESS; +} -- cgit v1.2.3 From 7791c8423f1f7f4dad94e753bae67461d5b80be8 Mon Sep 17 00:00:00 2001 From: Richard Weinberger Date: Wed, 10 Apr 2013 10:59:34 +0200 Subject: x86,efi: Check max_size only if it is non-zero. Some EFI implementations return always a MaximumVariableSize of 0, check against max_size only if it is non-zero. My Intel DQ67SW desktop board has such an implementation. Signed-off-by: Richard Weinberger Signed-off-by: Matt Fleming --- arch/x86/platform/efi/efi.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index c89c245eff4..3f96a487aa2 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -1018,7 +1018,12 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size) if (status != EFI_SUCCESS) return status; - if (!storage_size || size > remaining_size || size > max_size || + if (!max_size && remaining_size > size) + printk_once(KERN_ERR FW_BUG "Broken EFI implementation" + " is returning MaxVariableSize=0\n"); + + if (!storage_size || size > remaining_size || + (max_size && size > max_size) || (remaining_size - size) < (storage_size / 2)) return EFI_OUT_OF_RESOURCES; -- cgit v1.2.3 From cc5a080c5d40c36089bb08a8a16fa3fc7047fe0f Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Mon, 15 Apr 2013 13:09:46 -0700 Subject: efi: Pass boot services variable info to runtime code EFI variables can be flagged as being accessible only within boot services. This makes it awkward for us to figure out how much space they use at runtime. In theory we could figure this out by simply comparing the results from QueryVariableInfo() to the space used by all of our variables, but that fails if the platform doesn't garbage collect on every boot. Thankfully, calling QueryVariableInfo() while still inside boot services gives a more reliable answer. This patch passes that information from the EFI boot stub up to the efi platform code. Signed-off-by: Matthew Garrett Signed-off-by: Matt Fleming --- arch/x86/boot/compressed/eboot.c | 47 +++++++++++++++++++++++++++++++++++ arch/x86/include/asm/efi.h | 7 ++++++ arch/x86/include/uapi/asm/bootparam.h | 1 + arch/x86/platform/efi/efi.c | 21 ++++++++++++++++ 4 files changed, 76 insertions(+) (limited to 'arch/x86') diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c index c205035a6b9..8615f758182 100644 --- a/arch/x86/boot/compressed/eboot.c +++ b/arch/x86/boot/compressed/eboot.c @@ -251,6 +251,51 @@ static void find_bits(unsigned long mask, u8 *pos, u8 *size) *size = len; } +static efi_status_t setup_efi_vars(struct boot_params *params) +{ + struct setup_data *data; + struct efi_var_bootdata *efidata; + u64 store_size, remaining_size, var_size; + efi_status_t status; + + if (!sys_table->runtime->query_variable_info) + return EFI_UNSUPPORTED; + + data = (struct setup_data *)(unsigned long)params->hdr.setup_data; + + while (data && data->next) + data = (struct setup_data *)(unsigned long)data->next; + + status = efi_call_phys4(sys_table->runtime->query_variable_info, + EFI_VARIABLE_NON_VOLATILE | + EFI_VARIABLE_BOOTSERVICE_ACCESS | + EFI_VARIABLE_RUNTIME_ACCESS, &store_size, + &remaining_size, &var_size); + + if (status != EFI_SUCCESS) + return status; + + status = efi_call_phys3(sys_table->boottime->allocate_pool, + EFI_LOADER_DATA, sizeof(*efidata), &efidata); + + if (status != EFI_SUCCESS) + return status; + + efidata->data.type = SETUP_EFI_VARS; + efidata->data.len = sizeof(struct efi_var_bootdata) - + sizeof(struct setup_data); + efidata->data.next = 0; + efidata->store_size = store_size; + efidata->remaining_size = remaining_size; + efidata->max_var_size = var_size; + + if (data) + data->next = (unsigned long)efidata; + else + params->hdr.setup_data = (unsigned long)efidata; + +} + static efi_status_t setup_efi_pci(struct boot_params *params) { efi_pci_io_protocol *pci; @@ -1157,6 +1202,8 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table, setup_graphics(boot_params); + setup_efi_vars(boot_params); + setup_efi_pci(boot_params); status = efi_call_phys3(sys_table->boottime->allocate_pool, diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h index 60c89f30c72..2fb5d5884e2 100644 --- a/arch/x86/include/asm/efi.h +++ b/arch/x86/include/asm/efi.h @@ -102,6 +102,13 @@ extern void efi_call_phys_epilog(void); extern void efi_unmap_memmap(void); extern void efi_memory_uc(u64 addr, unsigned long size); +struct efi_var_bootdata { + struct setup_data data; + u64 store_size; + u64 remaining_size; + u64 max_var_size; +}; + #ifdef CONFIG_EFI static inline bool efi_is_native(void) diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h index c15ddaf9071..08744242b8d 100644 --- a/arch/x86/include/uapi/asm/bootparam.h +++ b/arch/x86/include/uapi/asm/bootparam.h @@ -6,6 +6,7 @@ #define SETUP_E820_EXT 1 #define SETUP_DTB 2 #define SETUP_PCI 3 +#define SETUP_EFI_VARS 4 /* ram_size flags */ #define RAMDISK_IMAGE_START_MASK 0x07FF diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 3f96a487aa2..977d1ce7e17 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -69,6 +69,10 @@ struct efi_memory_map memmap; static struct efi efi_phys __initdata; static efi_system_table_t efi_systab __initdata; +static u64 efi_var_store_size; +static u64 efi_var_remaining_size; +static u64 efi_var_max_var_size; + unsigned long x86_efi_facility; /* @@ -682,6 +686,9 @@ void __init efi_init(void) char vendor[100] = "unknown"; int i = 0; void *tmp; + struct setup_data *data; + struct efi_var_bootdata *efi_var_data; + u64 pa_data; #ifdef CONFIG_X86_32 if (boot_params.efi_info.efi_systab_hi || @@ -699,6 +706,20 @@ void __init efi_init(void) if (efi_systab_init(efi_phys.systab)) return; + pa_data = boot_params.hdr.setup_data; + while (pa_data) { + data = early_ioremap(pa_data, sizeof(*efi_var_data)); + if (data->type == SETUP_EFI_VARS) { + efi_var_data = (struct efi_var_bootdata *)data; + + efi_var_store_size = efi_var_data->store_size; + efi_var_remaining_size = efi_var_data->remaining_size; + efi_var_max_var_size = efi_var_data->max_var_size; + } + pa_data = data->next; + early_iounmap(data, sizeof(*efi_var_data)); + } + set_bit(EFI_SYSTEM_TABLES, &x86_efi_facility); /* -- cgit v1.2.3 From 31ff2f20d9003e74991d135f56e503fe776c127c Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Mon, 15 Apr 2013 13:09:47 -0700 Subject: efi: Distinguish between "remaining space" and actually used space EFI implementations distinguish between space that is actively used by a variable and space that merely hasn't been garbage collected yet. Space that hasn't yet been garbage collected isn't available for use and so isn't counted in the remaining_space field returned by QueryVariableInfo(). Combined with commit 68d9298 this can cause problems. Some implementations don't garbage collect until the remaining space is smaller than the maximum variable size, and as a result check_var_size() will always fail once more than 50% of the variable store has been used even if most of that space is marked as available for garbage collection. The user is unable to create new variables, and deleting variables doesn't increase the remaining space. The problem that 68d9298 was attempting to avoid was one where certain platforms fail if the actively used space is greater than 50% of the available storage space. We should be able to calculate that by simply summing the size of each available variable and subtracting that from the total storage space. With luck this will fix the problem described in https://bugzilla.kernel.org/show_bug.cgi?id=55471 without permitting damage to occur to the machines 68d9298 was attempting to fix. Signed-off-by: Matthew Garrett Signed-off-by: Matt Fleming --- arch/x86/platform/efi/efi.c | 106 +++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 100 insertions(+), 6 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 977d1ce7e17..4959e3f89d7 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -41,6 +41,7 @@ #include #include #include +#include #include #include @@ -51,6 +52,13 @@ #define EFI_DEBUG 1 +/* + * There's some additional metadata associated with each + * variable. Intel's reference implementation is 60 bytes - bump that + * to account for potential alignment constraints + */ +#define VAR_METADATA_SIZE 64 + struct efi __read_mostly efi = { .mps = EFI_INVALID_TABLE_ADDR, .acpi = EFI_INVALID_TABLE_ADDR, @@ -72,6 +80,9 @@ static efi_system_table_t efi_systab __initdata; static u64 efi_var_store_size; static u64 efi_var_remaining_size; static u64 efi_var_max_var_size; +static u64 boot_used_size; +static u64 boot_var_size; +static u64 active_size; unsigned long x86_efi_facility; @@ -166,8 +177,53 @@ static efi_status_t virt_efi_get_next_variable(unsigned long *name_size, efi_char16_t *name, efi_guid_t *vendor) { - return efi_call_virt3(get_next_variable, - name_size, name, vendor); + efi_status_t status; + static bool finished = false; + static u64 var_size; + + status = efi_call_virt3(get_next_variable, + name_size, name, vendor); + + if (status == EFI_NOT_FOUND) { + finished = true; + if (var_size < boot_used_size) { + boot_var_size = boot_used_size - var_size; + active_size += boot_var_size; + } else { + printk(KERN_WARNING FW_BUG "efi: Inconsistent initial sizes\n"); + } + } + + if (boot_used_size && !finished) { + unsigned long size; + u32 attr; + efi_status_t s; + void *tmp; + + s = virt_efi_get_variable(name, vendor, &attr, &size, NULL); + + if (s != EFI_BUFFER_TOO_SMALL || !size) + return status; + + tmp = kmalloc(size, GFP_ATOMIC); + + if (!tmp) + return status; + + s = virt_efi_get_variable(name, vendor, &attr, &size, tmp); + + if (s == EFI_SUCCESS && (attr & EFI_VARIABLE_NON_VOLATILE)) { + var_size += size; + var_size += ucs2_strsize(name, 1024); + active_size += size; + active_size += VAR_METADATA_SIZE; + active_size += ucs2_strsize(name, 1024); + } + + kfree(tmp); + } + + return status; } static efi_status_t virt_efi_set_variable(efi_char16_t *name, @@ -176,9 +232,34 @@ static efi_status_t virt_efi_set_variable(efi_char16_t *name, unsigned long data_size, void *data) { - return efi_call_virt5(set_variable, - name, vendor, attr, - data_size, data); + efi_status_t status; + u32 orig_attr = 0; + unsigned long orig_size = 0; + + status = virt_efi_get_variable(name, vendor, &orig_attr, &orig_size, + NULL); + + if (status != EFI_BUFFER_TOO_SMALL) + orig_size = 0; + + status = efi_call_virt5(set_variable, + name, vendor, attr, + data_size, data); + + if (status == EFI_SUCCESS) { + if (orig_size) { + active_size -= orig_size; + active_size -= ucs2_strsize(name, 1024); + active_size -= VAR_METADATA_SIZE; + } + if (data_size) { + active_size += data_size; + active_size += ucs2_strsize(name, 1024); + active_size += VAR_METADATA_SIZE; + } + } + + return status; } static efi_status_t virt_efi_query_variable_info(u32 attr, @@ -720,6 +801,8 @@ void __init efi_init(void) early_iounmap(data, sizeof(*efi_var_data)); } + boot_used_size = efi_var_store_size - efi_var_remaining_size; + set_bit(EFI_SYSTEM_TABLES, &x86_efi_facility); /* @@ -1042,10 +1125,21 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size) if (!max_size && remaining_size > size) printk_once(KERN_ERR FW_BUG "Broken EFI implementation" " is returning MaxVariableSize=0\n"); + /* + * Some firmware implementations refuse to boot if there's insufficient + * space in the variable store. We account for that by refusing the + * write if permitting it would reduce the available space to under + * 50%. However, some firmware won't reclaim variable space until + * after the used (not merely the actively used) space drops below + * a threshold. We can approximate that case with the value calculated + * above. If both the firmware and our calculations indicate that the + * available space would drop below 50%, refuse the write. + */ if (!storage_size || size > remaining_size || (max_size && size > max_size) || - (remaining_size - size) < (storage_size / 2)) + ((active_size + size + VAR_METADATA_SIZE > storage_size / 2) && + (remaining_size - size < storage_size / 2))) return EFI_OUT_OF_RESOURCES; return EFI_SUCCESS; -- cgit v1.2.3 From f6ce5002629e08eaa777ced3872a98f76845143e Mon Sep 17 00:00:00 2001 From: Sergey Vlasov Date: Tue, 16 Apr 2013 18:31:08 +0400 Subject: x86/Kconfig: Make EFI select UCS2_STRING The commit "efi: Distinguish between "remaining space" and actually used space" added usage of ucs2_*() functions to arch/x86/platform/efi/efi.c, but the only thing which selected UCS2_STRING was EFI_VARS, which is technically optional and can be built as a module. Signed-off-by: Sergey Vlasov Signed-off-by: Matt Fleming --- arch/x86/Kconfig | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86') diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index a4f24f5b121..01af8535f58 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1549,6 +1549,7 @@ config X86_SMAP config EFI bool "EFI runtime service support" depends on ACPI + select UCS2_STRING ---help--- This enables the kernel to use EFI runtime services that are available (such as the EFI variable services). -- cgit v1.2.3 From 3668011d4ad556224f7c012c1e870a6eaa0e59da Mon Sep 17 00:00:00 2001 From: Sergey Vlasov Date: Tue, 16 Apr 2013 18:31:09 +0400 Subject: efi: Export efi_query_variable_store() for efivars.ko Fixes build with CONFIG_EFI_VARS=m which was broken after the commit "x86, efivars: firmware bug workarounds should be in platform code". Signed-off-by: Sergey Vlasov Signed-off-by: Matt Fleming --- arch/x86/platform/efi/efi.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86') diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 4959e3f89d7..4f364c7c611 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -1144,3 +1144,4 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size) return EFI_SUCCESS; } +EXPORT_SYMBOL_GPL(efi_query_variable_store); -- cgit v1.2.3 From 8c58bf3eec3b8fc8162fe557e9361891c20758f2 Mon Sep 17 00:00:00 2001 From: Richard Weinberger Date: Wed, 17 Apr 2013 01:00:53 +0200 Subject: x86,efi: Implement efi_no_storage_paranoia parameter Using this parameter one can disable the storage_size/2 check if he is really sure that the UEFI does sane gc and fulfills the spec. This parameter is useful if a devices uses more than 50% of the storage by default. The Intel DQSW67 desktop board is such a sucker for exmaple. Signed-off-by: Richard Weinberger Signed-off-by: Matt Fleming --- arch/x86/platform/efi/efi.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 4f364c7c611..e4a86a677ce 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -113,6 +113,15 @@ static int __init setup_add_efi_memmap(char *arg) } early_param("add_efi_memmap", setup_add_efi_memmap); +static bool efi_no_storage_paranoia; + +static int __init setup_storage_paranoia(char *arg) +{ + efi_no_storage_paranoia = true; + return 0; +} +early_param("efi_no_storage_paranoia", setup_storage_paranoia); + static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc) { @@ -1137,7 +1146,10 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size) */ if (!storage_size || size > remaining_size || - (max_size && size > max_size) || + (max_size && size > max_size)) + return EFI_OUT_OF_RESOURCES; + + if (!efi_no_storage_paranoia && ((active_size + size + VAR_METADATA_SIZE > storage_size / 2) && (remaining_size - size < storage_size / 2))) return EFI_OUT_OF_RESOURCES; -- cgit v1.2.3