/* SPDX-License-Identifier: GPL-2.0-only */ #include #include #include #include #include #include #include #include #define FXSAVE_SIZE 512 #define SMM_CODE_SEGMENT_SIZE 0x10000 /* FXSAVE area during relocation. While it may not be strictly needed the SMM stub code relies on the FXSAVE area being non-zero to enable SSE instructions within SMM mode. */ static uint8_t fxsave_area_relocation[CONFIG_MAX_CPUS][FXSAVE_SIZE] __attribute__((aligned(16))); /* * Components that make up the SMRAM: * 1. Save state - the total save state memory used * 2. Stack - stacks for the CPUs in the SMM handler * 3. Stub - SMM stub code for calling into handler * 4. Handler - C-based SMM handler. * * The components are assumed to consist of one consecutive region. */ /* * The stub is the entry point that sets up protected mode and stacks for each * CPU. It then calls into the SMM handler module. It is encoded as an rmodule. */ extern unsigned char _binary_smmstub_start[]; /* Per CPU minimum stack size. */ #define SMM_MINIMUM_STACK_SIZE 32 struct cpu_smm_info { uint8_t active; uintptr_t smbase; uintptr_t entry; uintptr_t ss_start; uintptr_t code_start; uintptr_t code_end; }; struct cpu_smm_info cpus[CONFIG_MAX_CPUS] = { 0 }; /* * This method creates a map of all the CPU entry points, save state locations * and the beginning and end of code segments for each CPU. This map is used * during relocation to properly align as many CPUs that can fit into the SMRAM * region. For more information on how SMRAM works, refer to the latest Intel * developer's manuals (volume 3, chapter 34). SMRAM is divided up into the * following regions: * +-----------------+ Top of SMRAM * | | <- MSEG, FXSAVE * +-----------------+ * | common | * | smi handler | 64K * | | * +-----------------+ * | CPU 0 code seg | * +-----------------+ * | CPU 1 code seg | * +-----------------+ * | CPU x code seg | * +-----------------+ * | | * | | * +-----------------+ * | stacks | * +-----------------+ <- START of SMRAM * * The code below checks when a code segment is full and begins placing the remainder * CPUs in the lower segments. The entry point for each CPU is smbase + 0x8000 * and save state is smbase + 0x8000 + (0x8000 - state save size). Save state * area grows downward into the CPUs entry point. Therefore staggering too many * CPUs in one 32K block will corrupt CPU0's entry code as the save states move * downward. * input : smbase of first CPU (all other CPUs * will go below this address) * input : num_cpus in the system. The map will * be created from 0 to num_cpus. */ static int smm_create_map(uintptr_t smbase, unsigned int num_cpus, const struct smm_loader_params *params) { unsigned int i; struct rmodule smm_stub; unsigned int ss_size = params->per_cpu_save_state_size, stub_size; unsigned int smm_entry_offset = SMM_ENTRY_OFFSET; unsigned int seg_count = 0, segments = 0, available; unsigned int cpus_in_segment = 0; unsigned int base = smbase; if (rmodule_parse(&_binary_smmstub_start, &smm_stub)) { printk(BIOS_ERR, "%s: unable to get SMM module size\n", __func__); return 0; } stub_size = rmodule_memory_size(&smm_stub); /* How many CPUs can fit into one 64K segment? */ available = 0xFFFF - smm_entry_offset - ss_size - stub_size; if (available > 0) { cpus_in_segment = available / ss_size; /* minimum segments needed will always be 1 */ segments = num_cpus / cpus_in_segment + 1; printk(BIOS_DEBUG, "%s: cpus allowed in one segment %d\n", __func__, cpus_in_segment); printk(BIOS_DEBUG, "%s: min # of segments needed %d\n", __func__, segments); } else { printk(BIOS_ERR, "%s: not enough space in SMM to setup all CPUs\n", __func__); printk(BIOS_ERR, " save state & stub size need to be reduced\n"); printk(BIOS_ERR, " or increase SMRAM size\n"); return 0; } if (ARRAY_SIZE(cpus) < num_cpus) { printk(BIOS_ERR, "%s: increase MAX_CPUS in Kconfig\n", __func__); return 0; } for (i = 0; i < num_cpus; i++) { cpus[i].smbase = base; cpus[i].entry = base + smm_entry_offset; cpus[i].ss_start = cpus[i].entry + (smm_entry_offset - ss_size); cpus[i].code_start = cpus[i].entry; cpus[i].code_end = cpus[i].entry + stub_size; cpus[i].active = 1; base -= ss_size; seg_count++; if (seg_count >= cpus_in_segment) { base -= smm_entry_offset; seg_count = 0; } } if (CONFIG_DEFAULT_CONSOLE_LOGLEVEL >= BIOS_DEBUG) { seg_count = 0; for (i = 0; i < num_cpus; i++) { printk(BIOS_DEBUG, "CPU 0x%x\n", i); printk(BIOS_DEBUG, " smbase %lx entry %lx\n", cpus[i].smbase, cpus[i].entry); printk(BIOS_DEBUG, " ss_start %lx code_end %lx\n", cpus[i].ss_start, cpus[i].code_end); seg_count++; if (seg_count >= cpus_in_segment) { printk(BIOS_DEBUG, "-------------NEW CODE SEGMENT --------------\n"); seg_count = 0; } } } return 1; } /* * This method expects the smm relocation map to be complete. * This method does not read any HW registers, it simply uses a * map that was created during SMM setup. * input: cpu_num - cpu number which is used as an index into the * map to return the smbase */ u32 smm_get_cpu_smbase(unsigned int cpu_num) { if (cpu_num < CONFIG_MAX_CPUS) { if (cpus[cpu_num].active) return cpus[cpu_num].smbase; } return 0; } /* * This method assumes that at least 1 CPU has been set up from * which it will place other CPUs below its smbase ensuring that * save state does not clobber the first CPUs init code segment. The init * code which is the smm stub code is the same for all CPUs. They enter * smm, setup stacks (based on their apic id), enter protected mode * and then jump to the common smi handler. The stack is allocated * at the beginning of smram (aka tseg base, not smbase). The stack * pointer for each CPU is calculated by using its apic id * (code is in smm_stub.s) * Each entry point will now have the same stub code which, sets up the CPU * stack, enters protected mode and then jumps to the smi handler. It is * important to enter protected mode before the jump because the "jump to * address" might be larger than the 20bit address supported by real mode. * SMI entry right now is in real mode. * input: smbase - this is the smbase of the first cpu not the smbase * where tseg starts (aka smram_start). All CPUs code segment * and stack will be below this point except for the common * SMI handler which is one segment above * input: num_cpus - number of cpus that need relocation including * the first CPU (though its code is already loaded) * input: top of stack (stacks work downward by default in Intel HW) * output: return -1, if runtime smi code could not be installed. In * this case SMM will not work and any SMI's generated will * cause a CPU shutdown or general protection fault because * the appropriate smi handling code was not installed */ static int smm_place_entry_code(uintptr_t smbase, unsigned int num_cpus, uintptr_t stack_top, const struct smm_loader_params *params) { unsigned int i; unsigned int size; /* * Ensure there was enough space and the last CPUs smbase * did not encroach upon the stack. Stack top is smram start * + size of stack. */ if (cpus[num_cpus].active) { if (cpus[num_cpus - 1].smbase + SMM_ENTRY_OFFSET < stack_top) { printk(BIOS_ERR, "%s: stack encroachment\n", __func__); printk(BIOS_ERR, "%s: smbase %lx, stack_top %lx\n", __func__, cpus[num_cpus].smbase, stack_top); return 0; } } printk(BIOS_INFO, "%s: smbase %lx, stack_top %lx\n", __func__, cpus[num_cpus-1].smbase, stack_top); /* start at 1, the first CPU stub code is already there */ size = cpus[0].code_end - cpus[0].code_start; for (i = 1; i < num_cpus; i++) { memcpy((int *)cpus[i].code_start, (int *)cpus[0].code_start, size); printk(BIOS_DEBUG, "SMM Module: placing smm entry code at %lx, cpu # 0x%x\n", cpus[i].code_start, i); printk(BIOS_DEBUG, "%s: copying from %lx to %lx 0x%x bytes\n", __func__, cpus[0].code_start, cpus[i].code_start, size); } return 1; } /* * Place stacks in base -> base + size region, but ensure the stacks don't * overlap the staggered entry points. */ static void *smm_stub_place_stacks(char *base, struct smm_loader_params *params) { size_t total_stack_size; char *stacks_top; /* If stack space is requested assume the space lives in the lower * half of SMRAM. */ total_stack_size = params->per_cpu_stack_size * params->num_concurrent_stacks; printk(BIOS_DEBUG, "%s: cpus: %zx : stack space: needed -> %zx\n", __func__, params->num_concurrent_stacks, total_stack_size); /* There has to be at least one stack user. */ if (params->num_concurrent_stacks < 1) return NULL; /* Stacks extend down to SMBASE */ stacks_top = &base[total_stack_size]; printk(BIOS_DEBUG, "%s: exit, stack_top %p\n", __func__, stacks_top); return stacks_top; } /* * Place the staggered entry points for each CPU. The entry points are * staggered by the per CPU SMM save state size extending down from * SMM_ENTRY_OFFSET. */ static int smm_stub_place_staggered_entry_points(char *base, const struct smm_loader_params *params, const struct rmodule *smm_stub) { size_t stub_entry_offset; int rc = 1; stub_entry_offset = rmodule_entry_offset(smm_stub); /* Each CPU now has its own stub code, which enters protected mode, * sets up the stack, and then jumps to common SMI handler */ if (params->num_concurrent_save_states > 1 || stub_entry_offset != 0) { rc = smm_place_entry_code((uintptr_t)base, params->num_concurrent_save_states, (uintptr_t)params->stack_top, params); } return rc; } /* * The stub setup code assumes it is completely contained within the * default SMRAM size (0x10000) for the default SMI handler (entry at * 0x30000), but no assumption should be made for the permanent SMI handler. * The placement of CPU entry points for permanent handler are determined * by the number of CPUs in the system and the amount of SMRAM. * There are potentially 2 regions to place * within the default SMRAM size: * 1. Save state areas * 2. Stub code * * The save state always lives at the top of the CPUS smbase (and the entry * point is at offset 0x8000). This allows only a certain number of CPUs with * staggered entry points until the save state area comes down far enough to * overwrite/corrupt the entry code (stub code). Therefore, an SMM map is * created to avoid this corruption, see smm_create_map() above. * This module setup code works for the default (0x30000) SMM handler setup and the * permanent SMM handler. * The CPU stack is decided at runtime in the stub and is treaded as a continuous * region. As this might not fit the default SMRAM region, the same region used * by the permanent handler can be used during relocation. This is done via the * smram_start argument. */ static int smm_module_setup_stub(void *const smbase, const size_t smm_size, struct smm_loader_params *params, void *const fxsave_area, void *const smram_start) { size_t total_save_state_size; size_t smm_stub_size; char *smm_stub_loc; void *stacks_top; size_t size; char *base; size_t i; struct smm_stub_params *stub_params; struct rmodule smm_stub; base = smbase; size = smm_size; /* The number of concurrent stacks cannot exceed CONFIG_MAX_CPUS. */ if (params->num_concurrent_stacks > CONFIG_MAX_CPUS) { printk(BIOS_ERR, "%s: not enough stacks\n", __func__); return -1; } /* Fail if can't parse the smm stub rmodule. */ if (rmodule_parse(&_binary_smmstub_start, &smm_stub)) { printk(BIOS_ERR, "%s: unable to parse smm stub\n", __func__); return -1; } /* Adjust remaining size to account for save state. */ total_save_state_size = params->per_cpu_save_state_size * params->num_concurrent_save_states; if (total_save_state_size > size) { printk(BIOS_ERR, "%s: more state save space needed:need -> %zx:available->%zx\n", __func__, total_save_state_size, size); return -1; } size -= total_save_state_size; /* The save state size encroached over the first SMM entry point. */ if (size <= SMM_ENTRY_OFFSET) { printk(BIOS_ERR, "%s: encroachment over SMM entry point\n", __func__); printk(BIOS_ERR, "%s: state save size: %zx : smm_entry_offset -> %zx\n", __func__, size, (size_t)SMM_ENTRY_OFFSET); return -1; } /* Need a minimum stack size and alignment. */ if (params->per_cpu_stack_size <= SMM_MINIMUM_STACK_SIZE || (params->per_cpu_stack_size & 3) != 0) { printk(BIOS_ERR, "%s: need minimum stack size\n", __func__); return -1; } smm_stub_loc = NULL; smm_stub_size = rmodule_memory_size(&smm_stub); /* Put the stub at the main entry point */ smm_stub_loc = &base[SMM_ENTRY_OFFSET]; /* Stub is too big to fit. */ if (smm_stub_size > (size - SMM_ENTRY_OFFSET)) { printk(BIOS_ERR, "%s: stub is too big to fit\n", __func__); return -1; } /* The stacks, if requested, live in the lower half of SMRAM space * for default handler, but for relocated handler it lives at the beginning * of SMRAM which is TSEG base */ stacks_top = smm_stub_place_stacks(smram_start, params); if (stacks_top == NULL) { printk(BIOS_ERR, "%s: error assigning stacks\n", __func__); return -1; } params->stack_top = stacks_top; /* Load the stub. */ if (rmodule_load(smm_stub_loc, &smm_stub)) { printk(BIOS_ERR, "%s: load module failed\n", __func__); return -1; } if (!smm_stub_place_staggered_entry_points(base, params, &smm_stub)) { printk(BIOS_ERR, "%s: staggered entry points failed\n", __func__); return -1; } /* Setup the parameters for the stub code. */ stub_params = rmodule_parameters(&smm_stub); stub_params->stack_top = (uintptr_t)stacks_top; stub_params->stack_size = params->per_cpu_stack_size; stub_params->c_handler = (uintptr_t)params->handler; stub_params->fxsave_area = (uintptr_t)fxsave_area; stub_params->fxsave_area_size = FXSAVE_SIZE; const size_t total_stack_size = params->num_concurrent_stacks * params->per_cpu_stack_size; printk(BIOS_DEBUG, "%s: stack_end = 0x%zx\n", __func__, stub_params->stack_top - total_stack_size); printk(BIOS_DEBUG, "%s: stack_top = 0x%x\n", __func__, stub_params->stack_top); printk(BIOS_DEBUG, "%s: stack_size = 0x%x\n", __func__, stub_params->stack_size); printk(BIOS_DEBUG, "%s: runtime.start32_offset = 0x%x\n", __func__, stub_params->start32_offset); printk(BIOS_DEBUG, "%s: runtime.smm_size = 0x%zx\n", __func__, smm_size); /* Initialize the APIC id to CPU number table to be 1:1 */ for (i = 0; i < params->num_concurrent_stacks; i++) stub_params->apic_id_to_cpu[i] = i; /* Allow the initiator to manipulate SMM stub parameters. */ params->stub_params = stub_params; printk(BIOS_DEBUG, "SMM Module: stub loaded at %p. Will call %p\n", smm_stub_loc, params->handler); return 0; } /* * smm_setup_relocation_handler assumes the callback is already loaded in * memory. i.e. Another SMM module isn't chained to the stub. The other * assumption is that the stub will be entered from the default SMRAM * location: 0x30000 -> 0x40000. */ int smm_setup_relocation_handler(void * const perm_smram, struct smm_loader_params *params) { void *smram = (void *)(SMM_DEFAULT_BASE); printk(BIOS_SPEW, "%s: enter\n", __func__); /* There can't be more than 1 concurrent save state for the relocation * handler because all CPUs default to 0x30000 as SMBASE. */ if (params->num_concurrent_save_states > 1) return -1; /* A handler has to be defined to call for relocation. */ if (params->handler == NULL) return -1; /* Since the relocation handler always uses stack, adjust the number * of concurrent stack users to be CONFIG_MAX_CPUS. */ if (params->num_concurrent_stacks == 0) params->num_concurrent_stacks = CONFIG_MAX_CPUS; printk(BIOS_SPEW, "%s: exit\n", __func__); return smm_module_setup_stub(smram, SMM_DEFAULT_SIZE, params, fxsave_area_relocation, perm_smram); } /* *The SMM module is placed within the provided region in the following * manner: * +-----------------+ <- smram + size * | BIOS resource | * | list (STM) | * +-----------------+ * | fxsave area | * +-----------------+ * | smi handler | * | ... | * +-----------------+ <- cpu0 * | stub code | <- cpu1 * | stub code | <- cpu2 * | stub code | <- cpu3, etc * | | * | | * | | * | stacks | * +-----------------+ <- smram start * It should be noted that this algorithm will not work for * SMM_DEFAULT_SIZE SMRAM regions such as the A segment. This algorithm * expects a region large enough to encompass the handler and stacks * as well as the SMM_DEFAULT_SIZE. */ int smm_load_module(void *smram, size_t size, struct smm_loader_params *params) { struct rmodule smm_mod; struct smm_runtime *handler_mod_params; size_t total_stack_size; size_t handler_size; size_t module_alignment; size_t alignment_size; size_t fxsave_size; void *fxsave_area; size_t total_size = 0; char *base; void *smram_start = smram; if (size <= SMM_DEFAULT_SIZE) return -1; /* Load main SMI handler at the top of SMRAM * everything else will go below */ base = smram; base += size; /* Fail if can't parse the smm rmodule. */ if (rmodule_parse(&_binary_smm_start, &smm_mod)) return -1; /* Clear SMM region */ if (CONFIG(DEBUG_SMI)) memset(smram, 0xcd, size); total_stack_size = params->per_cpu_stack_size * params->num_concurrent_stacks; total_size += total_stack_size; /* Stacks are the base of SMRAM */ params->stack_top = smram + total_stack_size; /* MSEG starts at the top of SMRAM and works down */ if (CONFIG(STM)) { base -= CONFIG_MSEG_SIZE + CONFIG_BIOS_RESOURCE_LIST_SIZE; total_size += CONFIG_MSEG_SIZE + CONFIG_BIOS_RESOURCE_LIST_SIZE; } /* FXSAVE goes below MSEG */ if (CONFIG(SSE)) { fxsave_size = FXSAVE_SIZE * params->num_concurrent_stacks; fxsave_area = base - fxsave_size; base -= fxsave_size; total_size += fxsave_size; } else { fxsave_size = 0; fxsave_area = NULL; } handler_size = rmodule_memory_size(&smm_mod); base -= handler_size; total_size += handler_size; module_alignment = rmodule_load_alignment(&smm_mod); alignment_size = module_alignment - ((uintptr_t)base % module_alignment); if (alignment_size != module_alignment) { handler_size += alignment_size; base += alignment_size; } printk(BIOS_DEBUG, "%s: total_smm_space_needed %zx, available -> %zx\n", __func__, total_size, size); /* Does the required amount of memory exceed the SMRAM region size? */ if (total_size > size) { printk(BIOS_ERR, "%s: need more SMRAM\n", __func__); return -1; } if (handler_size > SMM_CODE_SEGMENT_SIZE) { printk(BIOS_ERR, "%s: increase SMM_CODE_SEGMENT_SIZE: handler_size = %zx\n", __func__, handler_size); return -1; } if (rmodule_load(base, &smm_mod)) return -1; params->handler = rmodule_entry(&smm_mod); handler_mod_params = rmodule_parameters(&smm_mod); handler_mod_params->smbase = (uintptr_t)smram; handler_mod_params->smm_size = size; handler_mod_params->save_state_size = params->real_cpu_save_state_size; handler_mod_params->num_cpus = params->num_concurrent_stacks; handler_mod_params->gnvs_ptr = (uintptr_t)acpi_get_gnvs(); printk(BIOS_DEBUG, "%s: smram_start: 0x%p\n", __func__, smram); printk(BIOS_DEBUG, "%s: smram_end: %p\n", __func__, smram + size); printk(BIOS_DEBUG, "%s: stack_top: %p\n", __func__, params->stack_top); printk(BIOS_DEBUG, "%s: handler start %p\n", __func__, params->handler); printk(BIOS_DEBUG, "%s: handler_size %zx\n", __func__, handler_size); printk(BIOS_DEBUG, "%s: fxsave_area %p\n", __func__, fxsave_area); printk(BIOS_DEBUG, "%s: fxsave_size %zx\n", __func__, fxsave_size); printk(BIOS_DEBUG, "%s: CONFIG_MSEG_SIZE 0x%x\n", __func__, CONFIG_MSEG_SIZE); printk(BIOS_DEBUG, "%s: CONFIG_BIOS_RESOURCE_LIST_SIZE 0x%x\n", __func__, CONFIG_BIOS_RESOURCE_LIST_SIZE); printk(BIOS_DEBUG, "%s: handler_mod_params.smbase = 0x%x\n", __func__, handler_mod_params->smbase); printk(BIOS_DEBUG, "%s: per_cpu_save_state_size = 0x%x\n", __func__, handler_mod_params->save_state_size); printk(BIOS_DEBUG, "%s: num_cpus = 0x%x\n", __func__, handler_mod_params->num_cpus); printk(BIOS_DEBUG, "%s: total_save_state_size = 0x%x\n", __func__, (handler_mod_params->save_state_size * handler_mod_params->num_cpus)); /* CPU 0 smbase goes first, all other CPUs * will be staggered below */ base -= SMM_CODE_SEGMENT_SIZE; printk(BIOS_DEBUG, "%s: cpu0 entry: %p\n", __func__, base); if (!smm_create_map((uintptr_t)base, params->num_concurrent_save_states, params)) { printk(BIOS_ERR, "%s: Error creating CPU map\n", __func__); return -1; } for (int i = 0; i < params->num_concurrent_stacks; i++) { handler_mod_params->save_state_top[i] = cpus[i].ss_start + params->per_cpu_save_state_size; } return smm_module_setup_stub(base, size, params, fxsave_area, smram_start); }