[PATCH] x86: Always to to fill acpi_rsdp_addr in boot params

Kairui Song kasong at redhat.com
Thu Mar 28 02:49:10 PDT 2019


Since kernel commit e6e094e053af75 ("x86/acpi, x86/boot: Take RSDP address
from boot params if available"), kernel accept a acpi_rsdp_addr param in
boot_params. Sync the x86_linux_param_header to support this param.

And previously we are already appending 'acpi_rsdp=' command line only for
loading crash kernel on EFI systems, it will be better to try to set the
boot param for any kernel get loaded, to help the kernel finding the
RSDP value more stably. Otherwise if the user decide to disable EFI
service in second kernel, it will fail to boot.

There is no better way to find the RSDP address from legacy BIOS
interface rather than scanning the memory region and search for it,
which will always be done by the kernel as a fallback, so we only
look for RSDP in previous boot params, cmdline and EFI firmware.

Signed-off-by: Kairui Song <kasong at redhat.com>
---
 include/x86/x86-linux.h            |  8 ++--
 kexec/arch/i386/crashdump-x86.c    | 34 +++++------------
 kexec/arch/i386/kexec-x86-common.c | 60 ++++++++++++++++++++++++++++++
 kexec/arch/i386/kexec-x86.h        |  1 +
 kexec/arch/i386/x86-linux-setup.c  |  6 ++-
 kexec/arch/i386/x86-linux-setup.h  |  1 +
 6 files changed, 80 insertions(+), 30 deletions(-)

diff --git a/include/x86/x86-linux.h b/include/x86/x86-linux.h
index 352ea02..a5d8df8 100644
--- a/include/x86/x86-linux.h
+++ b/include/x86/x86-linux.h
@@ -45,8 +45,7 @@ struct apm_bios_info {
 	uint16_t cseg_len;	/* 0x4e */
 	uint16_t cseg_16_len;	/* 0x50 */
 	uint16_t dseg_len;	/* 0x52 */
-	uint8_t  reserved[44];	/* 0x54 */
-};
+} __attribute__((packed));
 
 /*
  * EDD stuff
@@ -113,12 +112,15 @@ struct x86_linux_param_header {
 	uint8_t  reserved4[2];			/* 0x3e -- 0x3f reserved for future expansion */
 
 	struct apm_bios_info apm_bios_info;	/* 0x40 */
+	uint8_t  reserved4_1[28];		/* 0x54 */
+	uint64_t acpi_rsdp_addr;		/* 0x70 */
+	uint8_t  reserved4_2[8];		/* 0x78 */
 	struct drive_info_struct drive_info;	/* 0x80 */
 	struct sys_desc_table sys_desc_table;	/* 0xa0 */
 	uint32_t ext_ramdisk_image;		/* 0xc0 */
 	uint32_t ext_ramdisk_size;		/* 0xc4 */
 	uint32_t ext_cmd_line_ptr;		/* 0xc8 */
-	uint8_t reserved4_1[0x1c0 - 0xcc];	/* 0xe4 */
+	uint8_t reserved4_3[0x1c0 - 0xcc];	/* 0xe4 */
 	uint8_t efi_info[32];			/* 0x1c0 */
 	uint32_t alt_mem_k;			/* 0x1e0 */
 	uint8_t  reserved5[4];			/* 0x1e4 */
diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c
index 140f45b..262d157 100644
--- a/kexec/arch/i386/crashdump-x86.c
+++ b/kexec/arch/i386/crashdump-x86.c
@@ -787,35 +787,19 @@ static int sysfs_efi_runtime_map_exist(void)
 /* Appends 'acpi_rsdp=' commandline for efi boot crash dump */
 static void cmdline_add_efi(char *cmdline)
 {
-	FILE *fp;
-	int cmdlen, len;
-	char line[MAX_LINE], *s;
-	const char *acpis = " acpi_rsdp=";
+	int cmdlen;
+	uint64_t acpi_rsdp;
 
-	fp = fopen("/sys/firmware/efi/systab", "r");
-	if (!fp)
-		return;
+	acpi_rsdp = get_acpi_rsdp();
+	cmdlen = strlen(cmdline);
 
-	while(fgets(line, sizeof(line), fp) != 0) {
-		/* ACPI20= always goes before ACPI= */
-		if ((strstr(line, "ACPI20=")) || (strstr(line, "ACPI="))) {
-		        line[strlen(line) - 1] = '\0';
-			s = strchr(line, '=');
-			s += 1;
-			len = strlen(s) + strlen(acpis);
-			cmdlen = strlen(cmdline) + len;
-			if (cmdlen > (COMMAND_LINE_SIZE - 1))
-				die("Command line overflow\n");
-			strcat(cmdline, acpis);
-			strcat(cmdline, s);
-			dbgprintf("Command line after adding efi\n");
-			dbgprintf("%s\n", cmdline);
+	if (!acpi_rsdp)
+		return;
 
-			break;
-		}
-	}
+	if (cmdlen + sizeof(" acpi_rsdp=0x") + 16 > (COMMAND_LINE_SIZE - 1))
+		die("Command line overflow\n");
 
-	fclose(fp);
+	sprintf(cmdline + cmdlen, " acpi_rsdp=0x%016lx", acpi_rsdp);
 }
 
 static void get_backup_area(struct kexec_info *info,
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=");
+
+	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..5b00b42 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;
@@ -902,4 +901,7 @@ void setup_linux_system_parameters(struct kexec_info *info,
 
 	/* fill the EDD information */
 	setup_edd_info(real_mode);
+
+	/* Always try to fill acpi_rsdp_addr */
+	real_mode->acpi_rsdp_addr = get_acpi_rsdp();
 }
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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