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kboot: Add smbios support

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Add support for getting smbios from /sys/firmware/efi/systab, if
any. Add ptov mapping that uses mmap on /dev/mem to do the mapping with
64k pages (usually we only need 1 or two mappings).

Sponsored by:		Netflix
Differential Revision:	https://reviews.freebsd.org/D39792
This commit is contained in:
Warner Losh 2023-05-01 15:12:29 -06:00
parent facd0edbb2
commit a083d08676
1 changed files with 106 additions and 1 deletions
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107
stand/kboot/main.c
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@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
#include "host_syscall.h"
#include "kboot.h"
#include "stand.h"
#include <smbios.h>
struct arch_switch archsw;
extern void *_end;
@ -195,6 +196,107 @@ has_acpi(void)
return rsdp != 0;
}
/*
* SMBIOS support. We map the physical memory address we get into a VA in this
* address space with mmap with 64k pages. Once we're done, we cleanup any
* mappings we made.
*/
#define MAX_MAP 10
#define PAGE (64<<10)
static struct mapping
{
uintptr_t pa;
caddr_t va;
} map[MAX_MAP];
static int smbios_fd;
static int nmap;
caddr_t ptov(uintptr_t pa)
{
caddr_t va;
uintptr_t pa2;
struct mapping *m = map;
pa2 = rounddown(pa, PAGE);
for (int i = 0; i < nmap; i++, m++) {
if (m->pa == pa2) {
return (m->va + pa - m->pa);
}
}
if (nmap == MAX_MAP)
panic("Too many maps for smbios");
/*
* host_mmap returns small negative numbers on errors, can't return an
* error here, so we have to panic. The Linux wrapper will set errno
* based on this and then return HOST_MAP_FAILED. Since we're calling
* the raw system call we have to do that ourselves.
*/
va = host_mmap(0, PAGE, HOST_PROT_READ, HOST_MAP_SHARED, smbios_fd, pa2);
if ((intptr_t)va < 0 && (intptr_t)va >= -511)
panic("smbios mmap offset %#jx failed", (uintmax_t)pa2);
m = &map[nmap++];
m->pa = pa2;
m->va = va;
return (m->va + pa - m->pa);
}
static void
smbios_cleanup(void)
{
for (int i = 0; i < nmap; i++) {
host_munmap(map[i].va, PAGE);
}
}
static vm_offset_t
kboot_find_smbios(void)
{
char buffer[512 + 1];
char *walker, *ep;
if (!file2str("/sys/firmware/efi/systab", buffer, sizeof(buffer)))
return (0); /* Not an EFI system */
ep = buffer + strlen(buffer);
walker = buffer;
while (walker <= ep) {
if (strncmp("SMBIOS3=", walker, 8) == 0)
return((vm_offset_t)strtoull(walker + 8, NULL, 0));
if (strncmp("SMBIOS=", walker, 7) == 0)
return((vm_offset_t)strtoull(walker + 7, NULL, 0));
walker += strcspn(walker, "\n") + 1;
}
return (0);
}
static void
find_smbios(void)
{
char buf[40];
uintptr_t pa;
caddr_t va;
pa = kboot_find_smbios();
printf("SMBIOS at %#jx\n", (uintmax_t)pa);
if (pa == 0)
return;
snprintf(buf, sizeof(buf), "%#jx", (uintmax_t)pa);
setenv("hint.smbios.0.mem", buf, 1);
smbios_fd = host_open("/dev/mem", O_RDONLY, 0);
if (smbios_fd < 0) {
printf("Can't open /dev/mem to read smbios\n");
return;
}
va = ptov(pa);
printf("Start of smbios at pa %p va %p\n", (void *)pa, va);
smbios_detect(va);
smbios_cleanup();
host_close(smbios_fd);
}
static void
parse_file(const char *fn)
{
@ -300,6 +402,8 @@ main(int argc, const char **argv)
*/
find_acpi();
find_smbios();
interact(); /* doesn't return */
return (0);
@ -531,5 +635,6 @@ command_fdt(int argc, char *argv[])
return (command_fdt_internal(argc, argv));
}
COMMAND_SET(fdt, "fdt", "flattened device tree handling", command_fdt);