/* SPDX-License-Identifier: GPL-2.0-only */ #include "assert.h" #include #include #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 ss_start; uintptr_t ss_top; 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(const uintptr_t smbase, const unsigned int num_cpus, const struct smm_loader_params *params) { struct rmodule smm_stub; if (ARRAY_SIZE(cpus) < num_cpus) { printk(BIOS_ERR, "%s: increase MAX_CPUS in Kconfig\n", __func__); return 0; } if (rmodule_parse(&_binary_smmstub_start, &smm_stub)) { printk(BIOS_ERR, "%s: unable to get SMM module size\n", __func__); return 0; } /* * How many CPUs can fit into one 64K segment? * Make sure that the first stub does not overlap with the last save state of a segment. */ const size_t stub_size = rmodule_memory_size(&smm_stub); const size_t needed_ss_size = MAX(params->cpu_save_state_size, stub_size); const size_t cpus_per_segment = (SMM_CODE_SEGMENT_SIZE - SMM_ENTRY_OFFSET - stub_size) / needed_ss_size; if (cpus_per_segment == 0) { printk(BIOS_ERR, "%s: CPUs won't fit in segment. Broken stub or save state size\n", __func__); return 0; } for (unsigned int i = 0; i < num_cpus; i++) { if (i % cpus_per_segment == 0) printk(BIOS_DEBUG, "-------------NEW CODE SEGMENT --------------\n"); printk(BIOS_DEBUG, "CPU 0x%x\n", i); /* We copy the same stub for each CPU so they all need the same 'smbase'. */ const size_t segment_number = i / cpus_per_segment; cpus[i].smbase = smbase - SMM_CODE_SEGMENT_SIZE * segment_number - needed_ss_size * (i % cpus_per_segment); cpus[i].code_start = cpus[i].smbase + SMM_ENTRY_OFFSET; cpus[i].code_end = cpus[i].code_start + stub_size; cpus[i].ss_top = cpus[i].smbase + SMM_CODE_SEGMENT_SIZE; cpus[i].ss_start = cpus[i].ss_top - params->cpu_save_state_size; printk(BIOS_DEBUG, " Stub [0x%lx-0x%lx[\n", cpus[i].code_start, cpus[i].code_end); printk(BIOS_DEBUG, " Save state [0x%lx-0x%lx[\n", cpus[i].ss_start, cpus[i].ss_top); cpus[i].active = 1; } 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; } static uintptr_t stack_top; static size_t g_stack_size; int smm_setup_stack(const uintptr_t perm_smbase, const size_t perm_smram_size, const unsigned int total_cpus, const size_t stack_size) { /* Need a minimum stack size and alignment. */ if (stack_size <= SMM_MINIMUM_STACK_SIZE || (stack_size & 3) != 0) { printk(BIOS_ERR, "%s: need minimum stack size\n", __func__); return -1; } const size_t total_stack_size = total_cpus * stack_size; if (total_stack_size >= perm_smram_size) { printk(BIOS_ERR, "%s: Stack won't fit smram\n", __func__); return -1; } stack_top = perm_smbase + total_stack_size; g_stack_size = stack_size; return 0; } /* * 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, 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. */ static int smm_module_setup_stub(const uintptr_t smbase, const size_t smm_size, struct smm_loader_params *params, void *const fxsave_area) { struct rmodule smm_stub; if (rmodule_parse(&_binary_smmstub_start, &smm_stub)) { printk(BIOS_ERR, "%s: unable to parse smm stub\n", __func__); return -1; } const size_t stub_size = rmodule_memory_size(&smm_stub); /* Some sanity check */ if (stub_size >= SMM_ENTRY_OFFSET) { printk(BIOS_ERR, "%s: Stub too large\n", __func__); return -1; } const uintptr_t smm_stub_loc = smbase + SMM_ENTRY_OFFSET; if (rmodule_load((void *)smm_stub_loc, &smm_stub)) { printk(BIOS_ERR, "%s: load module failed\n", __func__); return -1; } struct smm_stub_params *stub_params = rmodule_parameters(&smm_stub); stub_params->stack_top = stack_top; stub_params->stack_size = g_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; /* Initialize the APIC id to CPU number table to be 1:1 */ for (int i = 0; i < params->num_cpus; i++) stub_params->apic_id_to_cpu[i] = i; printk(BIOS_DEBUG, "%s: stack_top = 0x%x\n", __func__, stub_params->stack_top); printk(BIOS_DEBUG, "%s: per cpu 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); if (!smm_stub_place_staggered_entry_points((void *)smbase, params, &smm_stub)) { printk(BIOS_ERR, "%s: staggered entry points failed\n", __func__); return -1; } printk(BIOS_DEBUG, "SMM Module: stub loaded at %lx. 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(struct smm_loader_params *params) { uintptr_t smram = 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_cpus == 0) params->num_cpus = CONFIG_MAX_CPUS; printk(BIOS_SPEW, "%s: exit\n", __func__); return smm_module_setup_stub(smram, SMM_DEFAULT_SIZE, params, fxsave_area_relocation); } static void setup_smihandler_params(struct smm_runtime *mod_params, uintptr_t smram_base, uintptr_t smram_size, struct smm_loader_params *loader_params) { mod_params->smbase = smram_base; mod_params->smm_size = smram_size; mod_params->save_state_size = loader_params->cpu_save_state_size; mod_params->num_cpus = loader_params->num_cpus; mod_params->gnvs_ptr = (uint32_t)(uintptr_t)acpi_get_gnvs(); const struct cbmem_entry *cbmemc; if (CONFIG(CONSOLE_CBMEM) && (cbmemc = cbmem_entry_find(CBMEM_ID_CONSOLE))) { mod_params->cbmemc = cbmem_entry_start(cbmemc); mod_params->cbmemc_size = cbmem_entry_size(cbmemc); } else { mod_params->cbmemc = 0; mod_params->cbmemc_size = 0; } for (int i = 0; i < loader_params->num_cpus; i++) mod_params->save_state_top[i] = cpus[i].ss_top; } /* *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. */ static int smm_load_module_tseg(const uintptr_t smram_base, const size_t smram_size, struct smm_loader_params *params) { if (smram_size <= SMM_DEFAULT_SIZE) return -1; struct rmodule smi_handler; if (rmodule_parse(&_binary_smm_start, &smi_handler)) return -1; const uintptr_t smram_top = smram_base + smram_size; const size_t stm_size = CONFIG(STM) ? CONFIG_MSEG_SIZE - CONFIG_BIOS_RESOURCE_LIST_SIZE : 0; const uintptr_t stm_base = CONFIG(STM) ? smram_top - stm_size : 0; if (stm_size) { printk(BIOS_DEBUG, "STM [0x%lx-0x%lx[\n", stm_base, stm_base + stm_size); printk(BIOS_DEBUG, "MSEG size 0x%x\n", CONFIG_MSEG_SIZE); printk(BIOS_DEBUG, "BIOS res list 0x%x\n", CONFIG_BIOS_RESOURCE_LIST_SIZE); } const size_t fx_save_area_size = CONFIG(SSE) ? FXSAVE_SIZE * params->num_cpus : 0; const uintptr_t fx_save_area_base = CONFIG(SSE) ? smram_top - stm_size - fx_save_area_size : 0; if (fx_save_area_size) printk(BIOS_DEBUG, "fx_save [0x%lx-0x%lx[\n", fx_save_area_base, fx_save_area_base + fx_save_area_size); const size_t handler_size = rmodule_memory_size(&smi_handler); const size_t handler_alignment = rmodule_load_alignment(&smi_handler); const uintptr_t handler_base = ALIGN_DOWN(smram_top - stm_size - fx_save_area_size - handler_size, handler_alignment); printk(BIOS_DEBUG, "smihandler [0x%lx-0x%lx[\n", handler_base, handler_base + handler_size); if (handler_base <= smram_base) { printk(BIOS_ERR, "Permanent handler won't FIT smram\n"); return -1; } const uintptr_t stub_segment_base = handler_base - SMM_CODE_SEGMENT_SIZE; if (!smm_create_map(stub_segment_base, params->num_concurrent_save_states, params)) { printk(BIOS_ERR, "%s: Error creating CPU map\n", __func__); return -1; } const uintptr_t lowest_stub = cpus[params->num_concurrent_save_states - 1].code_start; const uintptr_t smm_stack_top = smram_base + params->num_concurrent_save_states * CONFIG_SMM_MODULE_STACK_SIZE; printk(BIOS_DEBUG, "cpu stacks [0x%lx-0x%lx[\n", smram_base, smm_stack_top); if (lowest_stub < smm_stack_top) { printk(BIOS_ERR, "SMM stubs won't fit in SMRAM 0x%lx\n", cpus[params->num_concurrent_save_states - 1].code_start); return -1; } if (rmodule_load((void *)handler_base, &smi_handler)) return -1; struct smm_runtime *smihandler_params = rmodule_parameters(&smi_handler); params->handler = rmodule_entry(&smi_handler); setup_smihandler_params(smihandler_params, smram_base, smram_size, params); return smm_module_setup_stub(stub_segment_base, smram_size, params, (void *)fx_save_area_base); } /* *The SMM module is placed within the provided region in the following * manner: * +-----------------+ <- smram + size == 0xB0000 * | save states | * +-----------------+ * | fxsave area | * +-----------------+ * | smi handler | (or below the stubs if there is more space there) * | ... | * +-----------------+ <- cpu0 * | stub code | <- cpu1 * | stub code | <- cpu2 * | stub code | <- cpu3, etc * | | * | | * | | * | stacks | * +-----------------+ <- smram start = 0xA0000 */ static int smm_load_module_aseg(const uintptr_t smram_base, const size_t smram_size, struct smm_loader_params *params) { if (smram_size != SMM_DEFAULT_SIZE) return -1; struct rmodule smi_handler; if (rmodule_parse(&_binary_smm_start, &smi_handler)) return -1; if (!smm_create_map(smram_base, params->num_concurrent_save_states, params)) { printk(BIOS_ERR, "%s: Error creating CPU map\n", __func__); return -1; } const uintptr_t smm_stack_top = smram_base + params->num_concurrent_save_states * CONFIG_SMM_MODULE_STACK_SIZE; printk(BIOS_DEBUG, "cpu stacks [0x%lx-0x%lx[\n", smram_base, smm_stack_top); if (smm_stack_top > cpus[params->num_concurrent_save_states - 1].code_start) { printk(BIOS_ERR, "stack won't fit in smram\n"); return -1; } const uintptr_t save_state_bottom = cpus[params->num_concurrent_save_states - 1].ss_start; const size_t fx_save_area_size = CONFIG(SSE) ? FXSAVE_SIZE * params->num_cpus : 0; const uintptr_t fx_save_area_base = CONFIG(SSE) ? save_state_bottom - fx_save_area_size : 0; if (fx_save_area_size) { printk(BIOS_DEBUG, "fx_save [0x%lx-0x%lx[\n", fx_save_area_base, fx_save_area_base + fx_save_area_size); if (fx_save_area_base < cpus[0].code_end) { printk(BIOS_ERR, "fxsave won't fit in smram\n"); return -1; } } const size_t top_space = save_state_bottom - fx_save_area_size - cpus[0].code_end; const size_t bottom_space = cpus[params->num_concurrent_save_states - 1].code_start - smm_stack_top; const bool use_top = top_space >= bottom_space; const size_t handler_size = rmodule_memory_size(&smi_handler); const size_t handler_alignment = rmodule_load_alignment(&smi_handler); uintptr_t handler_base; if (use_top) { handler_base = ALIGN_DOWN(save_state_bottom - fx_save_area_size - handler_size, handler_alignment); if (handler_base < cpus[0].code_end) { printk(BIOS_ERR, "handler won't fit in top of smram\n"); return -1; } } else { handler_base = ALIGN_UP(stack_top, handler_alignment); const uintptr_t handler_top = handler_base + handler_size; if (handler_top > cpus[params->num_concurrent_save_states - 1].code_start) { printk(BIOS_ERR, "handler won't fit in bottom of smram\n"); return -1; } } printk(BIOS_DEBUG, "handler [0x%lx-0x%lx[\n", handler_base, handler_base + handler_size); if (rmodule_load((void *)handler_base, &smi_handler)) return -1; struct smm_runtime *smihandler_params = rmodule_parameters(&smi_handler); params->handler = rmodule_entry(&smi_handler); setup_smihandler_params(smihandler_params, smram_base, smram_size, params); return smm_module_setup_stub(smram_base, smram_size, params, (void *)fx_save_area_base); } int smm_load_module(const uintptr_t smram_base, const size_t smram_size, struct smm_loader_params *params) { if (CONFIG(SMM_ASEG)) return smm_load_module_aseg(smram_base, smram_size, params); else if (CONFIG(SMM_TSEG)) return smm_load_module_tseg(smram_base, smram_size, params); return -1; }