On 05/14/19 at 01:09pm, Kairui Song wrote:
> On x86 RSDP is fundamental for booting the machine. When second kernel
> is incapable of parsing the RSDP address (eg. kexec next kernel on an EFI
> system with EFI service disabled), kexec should prepare the RSDP address
> for second kernel.
>
> Introduce helpers for getting RSDP from multiple sources, including boot
> params, cmdline and EFI firmware.
>
> For legacy BIOS interface, there is no better way to find the RSDP address
> rather than scanning the memory region and search for it, and this will
> always be done by the kernel as a fallback, so this is no need to try to
> get the RSDP address for that case.
>
> Signed-off-by: Kairui Song <kasong@xxxxxxxxxx>
> ---
> kexec/arch/i386/kexec-x86-common.c | 60 ++++++++++++++++++++++++++++++
> kexec/arch/i386/kexec-x86.h | 1 +
> kexec/arch/i386/x86-linux-setup.c | 3 +-
> kexec/arch/i386/x86-linux-setup.h | 1 +
> 4 files changed, 63 insertions(+), 2 deletions(-)
>
> diff --git a/kexec/arch/i386/kexec-x86-common.c b/kexec/arch/i386/kexec-x86-common.c
> index de99758..4b8eb26 100644
> --- a/kexec/arch/i386/kexec-x86-common.c
> +++ b/kexec/arch/i386/kexec-x86-common.c
> @@ -39,6 +39,7 @@
> #include "../../firmware_memmap.h"
> #include "../../crashdump.h"
> #include "kexec-x86.h"
> +#include "x86-linux-setup.h"
> #include "../../kexec-xen.h"
>
> /* Used below but not present in (older?) xenctrl.h */
> @@ -392,4 +393,63 @@ int get_memory_ranges(struct memory_range **range, int *ranges,
> return ret;
> }
>
> +static uint64_t cmdline_get_acpi_rsdp(void) {
> + uint64_t acpi_rsdp = 0;
> + char *tmp_cmdline, *rsdp_param;
>
> + tmp_cmdline = get_command_line();
> + rsdp_param = strstr(tmp_cmdline, "acpi_rsdp=");
strstr will locate the first acpi_rsdp, what about multiple acpi_rsdp
provided?
BTW, if one provide a wrong adress in acpi_rsdp= cmdline then it is not
usable.
So not sure if adding this cmdline param is necessary, maybe only add
efi case will be reliable.
> +
> + if (rsdp_param)
> + sscanf(rsdp_param, "acpi_rsdp=%lx", &acpi_rsdp);
> +
> + free(tmp_cmdline);
> + return acpi_rsdp;
> +}
> +
> +static uint64_t bootparam_get_acpi_rsdp(void) {
> + uint64_t acpi_rsdp = 0;
> + off_t offset = offsetof(struct x86_linux_param_header, acpi_rsdp_addr);
> +
> + if (get_bootparam(&acpi_rsdp, offset, sizeof(acpi_rsdp)))
> + return 0;
> +
> + return acpi_rsdp;
> +}
> +
> +static uint64_t efi_get_acpi_rsdp(void) {
> + FILE *fp;
> + char line[MAX_LINE], *s;
> + uint64_t acpi_rsdp = 0;
> +
> + fp = fopen("/sys/firmware/efi/systab", "r");
> + if (!fp)
> + return acpi_rsdp;
> +
> + while(fgets(line, sizeof(line), fp) != 0) {
> + /* ACPI20= always goes before ACPI= */
> + if ((strstr(line, "ACPI20=")) || (strstr(line, "ACPI="))) {
> + s = strchr(line, '=') + 1;
> + sscanf(s, "0x%lx", &acpi_rsdp);
> + break;
> + }
> + }
> + fclose(fp);
> +
> + return acpi_rsdp;
> +}
> +
> +uint64_t get_acpi_rsdp(void)
> +{
> + uint64_t acpi_rsdp = 0;
> +
> + acpi_rsdp = cmdline_get_acpi_rsdp();
> +
> + if (!acpi_rsdp)
> + acpi_rsdp = bootparam_get_acpi_rsdp();
> +
> + if (!acpi_rsdp)
> + acpi_rsdp = efi_get_acpi_rsdp();
> +
> + return acpi_rsdp;
> +}
> diff --git a/kexec/arch/i386/kexec-x86.h b/kexec/arch/i386/kexec-x86.h
> index c2bcd37..1b58c3b 100644
> --- a/kexec/arch/i386/kexec-x86.h
> +++ b/kexec/arch/i386/kexec-x86.h
> @@ -86,4 +86,5 @@ int nbi_load(int argc, char **argv, const char *buf, off_t len,
> void nbi_usage(void);
>
> extern unsigned xen_e820_to_kexec_type(uint32_t type);
> +extern uint64_t get_acpi_rsdp(void);
> #endif /* KEXEC_X86_H */
> diff --git a/kexec/arch/i386/x86-linux-setup.c b/kexec/arch/i386/x86-linux-setup.c
> index 8fad115..5ca7c25 100644
> --- a/kexec/arch/i386/x86-linux-setup.c
> +++ b/kexec/arch/i386/x86-linux-setup.c
> @@ -123,7 +123,6 @@ void setup_linux_bootloader_parameters_high(
> cmdline_ptr[cmdline_len - 1] = '\0';
> }
>
> -static int get_bootparam(void *buf, off_t offset, size_t size);
> static int setup_linux_vesafb(struct x86_linux_param_header *real_mode)
> {
> struct fb_fix_screeninfo fix;
> @@ -452,7 +451,7 @@ char *find_mnt_by_fsname(char *fsname)
> return mntdir;
> }
>
> -static int get_bootparam(void *buf, off_t offset, size_t size)
> +int get_bootparam(void *buf, off_t offset, size_t size)
> {
> int data_file;
> char *debugfs_mnt, *sysfs_mnt;
> diff --git a/kexec/arch/i386/x86-linux-setup.h b/kexec/arch/i386/x86-linux-setup.h
> index f5d23d3..0c651e5 100644
> --- a/kexec/arch/i386/x86-linux-setup.h
> +++ b/kexec/arch/i386/x86-linux-setup.h
> @@ -21,6 +21,7 @@ static inline void setup_linux_bootloader_parameters(
> }
> void setup_linux_system_parameters(struct kexec_info *info,
> struct x86_linux_param_header *real_mode);
> +int get_bootparam(void *buf, off_t offset, size_t size);
>
>
> #define SETUP_BASE 0x90000
> --
> 2.20.1
>
>
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