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cpu/x86/smm_module_loader: Drop superfluous checks 

Checking if the stack encroaches on the entry points is done in other
parts of the code.

Change-Id: I275d5dda9c69cc89608450ae27dd5dbd581e3595
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63480
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
This commit is contained in:
Arthur Heymans 2022-04-07 21:52:59 +02:00 committed by Paul Fagerburg
parent 3b9f715183
commit 346db92f8c
1 changed files with 5 additions and 47 deletions
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52
src/cpu/x86/smm/smm_module_loader.c
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@ -169,42 +169,15 @@ u32 smm_get_cpu_smbase(unsigned int cpu_num)
* important to enter protected mode before the jump because the "jump to * important to enter protected mode before the jump because the "jump to
* address" might be larger than the 20bit address supported by real mode. * address" might be larger than the 20bit address supported by real mode.
* SMI entry right now is in 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 * input: num_cpus - number of cpus that need relocation including
* the first CPU (though its code is already loaded) * 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, static void smm_place_entry_code(const unsigned int num_cpus)
uintptr_t stack_top, const struct smm_loader_params *params)
{ {
unsigned int i; unsigned int i;
unsigned int size; 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 */ /* start at 1, the first CPU stub code is already there */
size = cpus[0].code_end - cpus[0].code_start; size = cpus[0].code_end - cpus[0].code_start;
for (i = 1; i < num_cpus; i++) { for (i = 1; i < num_cpus; i++) {
@ -215,7 +188,6 @@ static int smm_place_entry_code(uintptr_t smbase, unsigned int num_cpus,
printk(BIOS_DEBUG, "%s: copying from %lx to %lx 0x%x bytes\n", printk(BIOS_DEBUG, "%s: copying from %lx to %lx 0x%x bytes\n",
__func__, cpus[0].code_start, cpus[i].code_start, size); __func__, cpus[0].code_start, cpus[i].code_start, size);
} }
return 1;
} }
static uintptr_t stack_top; static uintptr_t stack_top;
@ -245,21 +217,10 @@ int smm_setup_stack(const uintptr_t perm_smbase, const size_t perm_smram_size,
* staggered by the per CPU SMM save state size extending down from * staggered by the per CPU SMM save state size extending down from
* SMM_ENTRY_OFFSET. * SMM_ENTRY_OFFSET.
*/ */
static int smm_stub_place_staggered_entry_points(char *base, static void smm_stub_place_staggered_entry_points(const struct smm_loader_params *params)
const struct smm_loader_params *params, const struct rmodule *smm_stub)
{ {
size_t stub_entry_offset; if (params->num_concurrent_save_states > 1)
int rc = 1; smm_place_entry_code(params->num_concurrent_save_states);
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;
} }
/* /*
@ -328,10 +289,7 @@ static int smm_module_setup_stub(const uintptr_t smbase, const size_t smm_size,
stub_params->start32_offset); stub_params->start32_offset);
printk(BIOS_DEBUG, "%s: runtime.smm_size = 0x%zx\n", __func__, smm_size); 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)) { smm_stub_place_staggered_entry_points(params);
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, printk(BIOS_DEBUG, "SMM Module: stub loaded at %lx. Will call %p\n", smm_stub_loc,
params->handler); params->handler);