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SubjectRe: [PATCH] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernels
On 04/16/19 at 11:52am, Borislav Petkov wrote:
> I'll queue the below in the next days if there are no more complaints:

As for the kexec breakage, even with the V3 patch, kexec still hangs on
a Lenovo T420 laptop. Kairui also reproduced the problem. So can we
wait a few days see if we can make some progress to find the cause?

>
> ---
> From: Junichi Nomura <j-nomura@ce.jp.nec.com>
>
> Commit
>
> 3a63f70bf4c3a ("x86/boot: Early parse RSDP and save it in boot_params")
>
> broke kexec boot on EFI systems. efi_get_rsdp_addr() in the early
> parsing code tries to search RSDP from the EFI tables but that will
> crash because the table address is virtual when the kernel was booted by
> kexec (set_virtual_address_map() has run in the first kernel and cannot
> be run again in the second kernel).
>
> In the case of kexec, the physical address of EFI tables is provided via
> efi_setup_data in boot_params, which is set up by kexec(1).
>
> Factor out the table parsing code and use different pointers depending
> on whether the kernel is booted by kexec or not.
>
> [ bp: Massage. ]
>
> Fixes: 3a63f70bf4c3a ("x86/boot: Early parse RSDP and save it in boot_params")
> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
> Signed-off-by: Borislav Petkov <bp@suse.de>
> Cc: Chao Fan <fanc.fnst@cn.fujitsu.com>
> Cc: Borislav Petkov <bp@suse.de>
> Cc: Dave Young <dyoung@redhat.com>
> Link: https://lkml.kernel.org/r/20190408231011.GA5402@jeru.linux.bs1.fc.nec.co.jp
> ---
> arch/x86/boot/compressed/acpi.c | 143 ++++++++++++++++++++++++--------
> 1 file changed, 107 insertions(+), 36 deletions(-)
>
> diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
> index 0ef4ad55b29b..8cecce1ac0cd 100644
> --- a/arch/x86/boot/compressed/acpi.c
> +++ b/arch/x86/boot/compressed/acpi.c
> @@ -44,17 +44,109 @@ static acpi_physical_address get_acpi_rsdp(void)
> return addr;
> }
>
> -/* Search EFI system tables for RSDP. */
> -static acpi_physical_address efi_get_rsdp_addr(void)
> +/*
> + * Search EFI system tables for RSDP. If both ACPI_20_TABLE_GUID and
> + * ACPI_TABLE_GUID are found, take the former, which has more features.
> + */
> +static acpi_physical_address
> +__efi_get_rsdp_addr(unsigned long config_tables, unsigned int nr_tables,
> + bool efi_64)
> {
> acpi_physical_address rsdp_addr = 0;
>
> #ifdef CONFIG_EFI
> - unsigned long systab, systab_tables, config_tables;
> + int i;
> +
> + /* Get EFI tables from systab. */
> + for (i = 0; i < nr_tables; i++) {
> + acpi_physical_address table;
> + efi_guid_t guid;
> +
> + if (efi_64) {
> + efi_config_table_64_t *tbl = (efi_config_table_64_t *) config_tables + i;
> +
> + guid = tbl->guid;
> + table = tbl->table;
> +
> + if (!IS_ENABLED(CONFIG_X86_64) && table >> 32) {
> + debug_putstr("Error getting RSDP address: EFI config table located above 4GB.\n");
> + return 0;
> + }
> + } else {
> + efi_config_table_32_t *tbl = (efi_config_table_32_t *) config_tables + i;
> +
> + guid = tbl->guid;
> + table = tbl->table;
> + }
> +
> + if (!(efi_guidcmp(guid, ACPI_TABLE_GUID)))
> + rsdp_addr = table;
> + else if (!(efi_guidcmp(guid, ACPI_20_TABLE_GUID)))
> + return table;
> + }
> +#endif
> + return rsdp_addr;
> +}
> +
> +/* EFI/kexec support is 64-bit only. */
> +#ifdef CONFIG_X86_64
> +static struct efi_setup_data *get_kexec_setup_data_addr(void)
> +{
> + struct setup_data *data;
> + u64 pa_data;
> +
> + pa_data = boot_params->hdr.setup_data;
> + while (pa_data) {
> + data = (struct setup_data *)pa_data;
> + if (data->type == SETUP_EFI)
> + return (struct efi_setup_data *)(pa_data + sizeof(struct setup_data));
> +
> + pa_data = data->next;
> + }
> + return NULL;
> +}
> +
> +static acpi_physical_address kexec_get_rsdp_addr(void)
> +{
> + efi_system_table_64_t *systab;
> + struct efi_setup_data *esd;
> + struct efi_info *ei;
> + char *sig;
> +
> + esd = (struct efi_setup_data *)get_kexec_setup_data_addr();
> + if (!esd)
> + return 0;
> +
> + if (!esd->tables) {
> + debug_putstr("Wrong kexec SETUP_EFI data.\n");
> + return 0;
> + }
> +
> + ei = &boot_params->efi_info;
> + sig = (char *)&ei->efi_loader_signature;
> + if (strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) {
> + debug_putstr("Wrong kexec EFI loader signature.\n");
> + return 0;
> + }
> +
> + /* Get systab from boot params. */
> + systab = (efi_system_table_64_t *) (ei->efi_systab | ((__u64)ei->efi_systab_hi << 32));
> + if (!systab)
> + error("EFI system table not found in kexec boot_params.");
> +
> + return __efi_get_rsdp_addr((unsigned long)esd->tables, systab->nr_tables, true);
> +}
> +#else
> +static acpi_physical_address kexec_get_rsdp_addr(void) { return 0; }
> +#endif /* CONFIG_X86_64 */
> +
> +static acpi_physical_address efi_get_rsdp_addr(void)
> +{
> +#ifdef CONFIG_EFI
> + unsigned long systab, config_tables;
> unsigned int nr_tables;
> struct efi_info *ei;
> bool efi_64;
> - int size, i;
> char *sig;
>
> ei = &boot_params->efi_info;
> @@ -88,49 +180,20 @@ static acpi_physical_address efi_get_rsdp_addr(void)
>
> config_tables = stbl->tables;
> nr_tables = stbl->nr_tables;
> - size = sizeof(efi_config_table_64_t);
> } else {
> efi_system_table_32_t *stbl = (efi_system_table_32_t *)systab;
>
> config_tables = stbl->tables;
> nr_tables = stbl->nr_tables;
> - size = sizeof(efi_config_table_32_t);
> }
>
> if (!config_tables)
> error("EFI config tables not found.");
>
> - /* Get EFI tables from systab. */
> - for (i = 0; i < nr_tables; i++) {
> - acpi_physical_address table;
> - efi_guid_t guid;
> -
> - config_tables += size;
> -
> - if (efi_64) {
> - efi_config_table_64_t *tbl = (efi_config_table_64_t *)config_tables;
> -
> - guid = tbl->guid;
> - table = tbl->table;
> -
> - if (!IS_ENABLED(CONFIG_X86_64) && table >> 32) {
> - debug_putstr("Error getting RSDP address: EFI config table located above 4GB.\n");
> - return 0;
> - }
> - } else {
> - efi_config_table_32_t *tbl = (efi_config_table_32_t *)config_tables;
> -
> - guid = tbl->guid;
> - table = tbl->table;
> - }
> -
> - if (!(efi_guidcmp(guid, ACPI_TABLE_GUID)))
> - rsdp_addr = table;
> - else if (!(efi_guidcmp(guid, ACPI_20_TABLE_GUID)))
> - return table;
> - }
> + return __efi_get_rsdp_addr(config_tables, nr_tables, efi_64);
> +#else
> + return 0;
> #endif
> - return rsdp_addr;
> }
>
> static u8 compute_checksum(u8 *buffer, u32 length)
> @@ -220,6 +283,14 @@ acpi_physical_address get_rsdp_addr(void)
> if (!pa)
> pa = boot_params->acpi_rsdp_addr;
>
> + /*
> + * Try to get EFI data from setup_data. This can happen when we're a
> + * kexec'ed kernel and kexec(1) has passed all the required EFI info to
> + * us.
> + */
> + if (!pa)
> + pa = kexec_get_rsdp_addr();
> +
> if (!pa)
> pa = efi_get_rsdp_addr();
>
> --
> 2.21.0
>
>
> --
> Regards/Gruss,
> Boris.
>
> Good mailing practices for 400: avoid top-posting and trim the reply.

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