watchdog: hpwdt: Remove legacy NMI sourcing.

Gen8 and prior Proliant systems supported the "CRU" interface
to firmware.  This interfaces allows linux to "call back" into firmware
to source the cause of an NMI.  This feature isn't fully utilized
as the actual source of the NMI isn't printed, the driver only
indicates that the source couldn't be determined when the call
fails.

With the advent of Gen9, iCRU replaces the CRU. The call back
feature is no longer available in firmware.  To be compatible and
not attempt to call back into firmware on system not supporting CRU,
the SMBIOS table is consulted to determine if it is safe to
make the call back or not.

This results in about half of the driver code being devoted
to either making CRU calls or determing if it is safe to make
CRU calls.  As noted, the driver isn't really using the results of
the CRU calls.

Furthermore, as a consequence of the Spectre security issue, the
BIOS/EFI calls are being wrapped into Spectre-disabling section.
Removing the call back in hpwdt_pretimeout assists in this effort.

As the CRU sourcing of the NMI isn't required for handling the
NMI and there are security concerns with making the call back, remove
the legacy (pre Gen9) NMI sourcing and the DMI code to determine if
the system had the CRU interface.

Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

1 files changed, 9 insertions, 492 deletions

diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
index f1f00dfc0e68..b0a158073abd 100644
--- a/drivers/watchdog/hpwdt.c
+++ b/drivers/watchdog/hpwdt.c
@@ -28,16 +28,7 @@
 #include <linux/types.h>
 #include <linux/uaccess.h>
 #include <linux/watchdog.h>
-#ifdef CONFIG_HPWDT_NMI_DECODING
-#include <linux/dmi.h>
-#include <linux/spinlock.h>
-#include <linux/nmi.h>
-#include <linux/kdebug.h>
-#include <linux/notifier.h>
-#include <asm/set_memory.h>
-#endif /* CONFIG_HPWDT_NMI_DECODING */
 #include <asm/nmi.h>
-#include <asm/frame.h>
 
 #define HPWDT_VERSION			"1.4.0"
 #define SECS_TO_TICKS(secs)		((secs) * 1000 / 128)
@@ -48,6 +39,9 @@
 static unsigned int soft_margin = DEFAULT_MARGIN;	/* in seconds */
 static unsigned int reload;			/* the computed soft_margin */
 static bool nowayout = WATCHDOG_NOWAYOUT;
+#ifdef CONFIG_HPWDT_NMI_DECODING
+static unsigned int allow_kdump = 1;
+#endif
 static char expect_release;
 static unsigned long hpwdt_is_open;
 
@@ -63,373 +57,6 @@ static const struct pci_device_id hpwdt_devices[] = {
 };
 MODULE_DEVICE_TABLE(pci, hpwdt_devices);
 
-#ifdef CONFIG_HPWDT_NMI_DECODING
-#define PCI_BIOS32_SD_VALUE		0x5F32335F	/* "_32_" */
-#define CRU_BIOS_SIGNATURE_VALUE	0x55524324
-#define PCI_BIOS32_PARAGRAPH_LEN	16
-#define PCI_ROM_BASE1			0x000F0000
-#define ROM_SIZE			0x10000
-
-struct bios32_service_dir {
-	u32 signature;
-	u32 entry_point;
-	u8 revision;
-	u8 length;
-	u8 checksum;
-	u8 reserved[5];
-};
-
-/* type 212 */
-struct smbios_cru64_info {
-	u8 type;
-	u8 byte_length;
-	u16 handle;
-	u32 signature;
-	u64 physical_address;
-	u32 double_length;
-	u32 double_offset;
-};
-#define SMBIOS_CRU64_INFORMATION	212
-
-/* type 219 */
-struct smbios_proliant_info {
-	u8 type;
-	u8 byte_length;
-	u16 handle;
-	u32 power_features;
-	u32 omega_features;
-	u32 reserved;
-	u32 misc_features;
-};
-#define SMBIOS_ICRU_INFORMATION		219
-
-
-struct cmn_registers {
-	union {
-		struct {
-			u8 ral;
-			u8 rah;
-			u16 rea2;
-		};
-		u32 reax;
-	} u1;
-	union {
-		struct {
-			u8 rbl;
-			u8 rbh;
-			u8 reb2l;
-			u8 reb2h;
-		};
-		u32 rebx;
-	} u2;
-	union {
-		struct {
-			u8 rcl;
-			u8 rch;
-			u16 rec2;
-		};
-		u32 recx;
-	} u3;
-	union {
-		struct {
-			u8 rdl;
-			u8 rdh;
-			u16 red2;
-		};
-		u32 redx;
-	} u4;
-
-	u32 resi;
-	u32 redi;
-	u16 rds;
-	u16 res;
-	u32 reflags;
-}  __attribute__((packed));
-
-static unsigned int hpwdt_nmi_decoding;
-static unsigned int allow_kdump = 1;
-static unsigned int is_icru;
-static unsigned int is_uefi;
-static DEFINE_SPINLOCK(rom_lock);
-static void *cru_rom_addr;
-static struct cmn_registers cmn_regs;
-
-extern asmlinkage void asminline_call(struct cmn_registers *pi86Regs,
-						unsigned long *pRomEntry);
-
-#ifdef CONFIG_X86_32
-/* --32 Bit Bios------------------------------------------------------------ */
-
-#define HPWDT_ARCH	32
-
-asm(".text                          \n\t"
-    ".align 4                       \n\t"
-    ".globl asminline_call	    \n"
-    "asminline_call:                \n\t"
-    "pushl       %ebp               \n\t"
-    "movl        %esp, %ebp         \n\t"
-    "pusha                          \n\t"
-    "pushf                          \n\t"
-    "push        %es                \n\t"
-    "push        %ds                \n\t"
-    "pop         %es                \n\t"
-    "movl        8(%ebp),%eax       \n\t"
-    "movl        4(%eax),%ebx       \n\t"
-    "movl        8(%eax),%ecx       \n\t"
-    "movl        12(%eax),%edx      \n\t"
-    "movl        16(%eax),%esi      \n\t"
-    "movl        20(%eax),%edi      \n\t"
-    "movl        (%eax),%eax        \n\t"
-    "push        %cs                \n\t"
-    "call        *12(%ebp)          \n\t"
-    "pushf                          \n\t"
-    "pushl       %eax               \n\t"
-    "movl        8(%ebp),%eax       \n\t"
-    "movl        %ebx,4(%eax)       \n\t"
-    "movl        %ecx,8(%eax)       \n\t"
-    "movl        %edx,12(%eax)      \n\t"
-    "movl        %esi,16(%eax)      \n\t"
-    "movl        %edi,20(%eax)      \n\t"
-    "movw        %ds,24(%eax)       \n\t"
-    "movw        %es,26(%eax)       \n\t"
-    "popl        %ebx               \n\t"
-    "movl        %ebx,(%eax)        \n\t"
-    "popl        %ebx               \n\t"
-    "movl        %ebx,28(%eax)      \n\t"
-    "pop         %es                \n\t"
-    "popf                           \n\t"
-    "popa                           \n\t"
-    "leave                          \n\t"
-    "ret                            \n\t"
-    ".previous");
-
-
-/*
- *	cru_detect
- *
- *	Routine Description:
- *	This function uses the 32-bit BIOS Service Directory record to
- *	search for a $CRU record.
- *
- *	Return Value:
- *	0        :  SUCCESS
- *	<0       :  FAILURE
- */
-static int cru_detect(unsigned long map_entry,
-	unsigned long map_offset)
-{
-	void *bios32_map;
-	unsigned long *bios32_entrypoint;
-	unsigned long cru_physical_address;
-	unsigned long cru_length;
-	unsigned long physical_bios_base = 0;
-	unsigned long physical_bios_offset = 0;
-	int retval = -ENODEV;
-
-	bios32_map = ioremap(map_entry, (2 * PAGE_SIZE));
-
-	if (bios32_map == NULL)
-		return -ENODEV;
-
-	bios32_entrypoint = bios32_map + map_offset;
-
-	cmn_regs.u1.reax = CRU_BIOS_SIGNATURE_VALUE;
-
-	set_memory_x((unsigned long)bios32_map, 2);
-	asminline_call(&cmn_regs, bios32_entrypoint);
-
-	if (cmn_regs.u1.ral != 0) {
-		pr_warn("Call succeeded but with an error: 0x%x\n",
-			cmn_regs.u1.ral);
-	} else {
-		physical_bios_base = cmn_regs.u2.rebx;
-		physical_bios_offset = cmn_regs.u4.redx;
-		cru_length = cmn_regs.u3.recx;
-		cru_physical_address =
-			physical_bios_base + physical_bios_offset;
-
-		/* If the values look OK, then map it in. */
-		if ((physical_bios_base + physical_bios_offset)) {
-			cru_rom_addr =
-				ioremap(cru_physical_address, cru_length);
-			if (cru_rom_addr) {
-				set_memory_x((unsigned long)cru_rom_addr & PAGE_MASK,
-					(cru_length + PAGE_SIZE - 1) >> PAGE_SHIFT);
-				retval = 0;
-			}
-		}
-
-		pr_debug("CRU Base Address:   0x%lx\n", physical_bios_base);
-		pr_debug("CRU Offset Address: 0x%lx\n", physical_bios_offset);
-		pr_debug("CRU Length:         0x%lx\n", cru_length);
-		pr_debug("CRU Mapped Address: %p\n", &cru_rom_addr);
-	}
-	iounmap(bios32_map);
-	return retval;
-}
-
-/*
- *	bios_checksum
- */
-static int bios_checksum(const char __iomem *ptr, int len)
-{
-	char sum = 0;
-	int i;
-
-	/*
-	 * calculate checksum of size bytes. This should add up
-	 * to zero if we have a valid header.
-	 */
-	for (i = 0; i < len; i++)
-		sum += ptr[i];
-
-	return ((sum == 0) && (len > 0));
-}
-
-/*
- *	bios32_present
- *
- *	Routine Description:
- *	This function finds the 32-bit BIOS Service Directory
- *
- *	Return Value:
- *	0        :  SUCCESS
- *	<0       :  FAILURE
- */
-static int bios32_present(const char __iomem *p)
-{
-	struct bios32_service_dir *bios_32_ptr;
-	int length;
-	unsigned long map_entry, map_offset;
-
-	bios_32_ptr = (struct bios32_service_dir *) p;
-
-	/*
-	 * Search for signature by checking equal to the swizzled value
-	 * instead of calling another routine to perform a strcmp.
-	 */
-	if (bios_32_ptr->signature == PCI_BIOS32_SD_VALUE) {
-		length = bios_32_ptr->length * PCI_BIOS32_PARAGRAPH_LEN;
-		if (bios_checksum(p, length)) {
-			/*
-			 * According to the spec, we're looking for the
-			 * first 4KB-aligned address below the entrypoint
-			 * listed in the header. The Service Directory code
-			 * is guaranteed to occupy no more than 2 4KB pages.
-			 */
-			map_entry = bios_32_ptr->entry_point & ~(PAGE_SIZE - 1);
-			map_offset = bios_32_ptr->entry_point - map_entry;
-
-			return cru_detect(map_entry, map_offset);
-		}
-	}
-	return -ENODEV;
-}
-
-static int detect_cru_service(void)
-{
-	char __iomem *p, *q;
-	int rc = -1;
-
-	/*
-	 * Search from 0x0f0000 through 0x0fffff, inclusive.
-	 */
-	p = ioremap(PCI_ROM_BASE1, ROM_SIZE);
-	if (p == NULL)
-		return -ENOMEM;
-
-	for (q = p; q < p + ROM_SIZE; q += 16) {
-		rc = bios32_present(q);
-		if (!rc)
-			break;
-	}
-	iounmap(p);
-	return rc;
-}
-/* ------------------------------------------------------------------------- */
-#endif /* CONFIG_X86_32 */
-#ifdef CONFIG_X86_64
-/* --64 Bit Bios------------------------------------------------------------ */
-
-#define HPWDT_ARCH	64
-
-asm(".text                      \n\t"
-    ".align 4                   \n\t"
-    ".globl asminline_call	\n\t"
-    ".type asminline_call, @function \n\t"
-    "asminline_call:            \n\t"
-    FRAME_BEGIN
-    "pushq      %rax            \n\t"
-    "pushq      %rbx            \n\t"
-    "pushq      %rdx            \n\t"
-    "pushq      %r12            \n\t"
-    "pushq      %r9             \n\t"
-    "movq       %rsi, %r12      \n\t"
-    "movq       %rdi, %r9       \n\t"
-    "movl       4(%r9),%ebx     \n\t"
-    "movl       8(%r9),%ecx     \n\t"
-    "movl       12(%r9),%edx    \n\t"
-    "movl       16(%r9),%esi    \n\t"
-    "movl       20(%r9),%edi    \n\t"
-    "movl       (%r9),%eax      \n\t"
-    "call       *%r12           \n\t"
-    "pushfq                     \n\t"
-    "popq        %r12           \n\t"
-    "movl       %eax, (%r9)     \n\t"
-    "movl       %ebx, 4(%r9)    \n\t"
-    "movl       %ecx, 8(%r9)    \n\t"
-    "movl       %edx, 12(%r9)   \n\t"
-    "movl       %esi, 16(%r9)   \n\t"
-    "movl       %edi, 20(%r9)   \n\t"
-    "movq       %r12, %rax      \n\t"
-    "movl       %eax, 28(%r9)   \n\t"
-    "popq       %r9             \n\t"
-    "popq       %r12            \n\t"
-    "popq       %rdx            \n\t"
-    "popq       %rbx            \n\t"
-    "popq       %rax            \n\t"
-    FRAME_END
-    "ret                        \n\t"
-    ".previous");
-
-/*
- *	dmi_find_cru
- *
- *	Routine Description:
- *	This function checks whether or not a SMBIOS/DMI record is
- *	the 64bit CRU info or not
- */
-static void dmi_find_cru(const struct dmi_header *dm, void *dummy)
-{
-	struct smbios_cru64_info *smbios_cru64_ptr;
-	unsigned long cru_physical_address;
-
-	if (dm->type == SMBIOS_CRU64_INFORMATION) {
-		smbios_cru64_ptr = (struct smbios_cru64_info *) dm;
-		if (smbios_cru64_ptr->signature == CRU_BIOS_SIGNATURE_VALUE) {
-			cru_physical_address =
-				smbios_cru64_ptr->physical_address +
-				smbios_cru64_ptr->double_offset;
-			cru_rom_addr = ioremap(cru_physical_address,
-				smbios_cru64_ptr->double_length);
-			set_memory_x((unsigned long)cru_rom_addr & PAGE_MASK,
-				smbios_cru64_ptr->double_length >> PAGE_SHIFT);
-		}
-	}
-}
-
-static int detect_cru_service(void)
-{
-	cru_rom_addr = NULL;
-
-	dmi_walk(dmi_find_cru, NULL);
-
-	/* if cru_rom_addr has been set then we found a CRU service */
-	return ((cru_rom_addr != NULL) ? 0 : -ENODEV);
-}
-/* ------------------------------------------------------------------------- */
-#endif /* CONFIG_X86_64 */
-#endif /* CONFIG_HPWDT_NMI_DECODING */
 
 /*
  *	Watchdog operations
@@ -486,30 +113,12 @@ static int hpwdt_my_nmi(void)
  */
 static int hpwdt_pretimeout(unsigned int ulReason, struct pt_regs *regs)
 {
-	unsigned long rom_pl;
-	static int die_nmi_called;
-
-	if (!hpwdt_nmi_decoding)
-		return NMI_DONE;
-
 	if ((ulReason == NMI_UNKNOWN) && !hpwdt_my_nmi())
 		return NMI_DONE;
 
-	spin_lock_irqsave(&rom_lock, rom_pl);
-	if (!die_nmi_called && !is_icru && !is_uefi)
-		asminline_call(&cmn_regs, cru_rom_addr);
-	die_nmi_called = 1;
-	spin_unlock_irqrestore(&rom_lock, rom_pl);
-
 	if (allow_kdump)
 		hpwdt_stop();
 
-	if (!is_icru && !is_uefi) {
-		if (cmn_regs.u1.ral == 0) {
-			nmi_panic(regs, "An NMI occurred, but unable to determine source.\n");
-			return NMI_HANDLED;
-		}
-	}
 	nmi_panic(regs, "An NMI occurred. Depending on your system the reason "
 		"for the NMI is logged in any one of the following "
 		"resources:\n"
@@ -675,84 +284,11 @@ static struct miscdevice hpwdt_miscdev = {
  *	Init & Exit
  */
 
-#ifdef CONFIG_HPWDT_NMI_DECODING
-#ifdef CONFIG_X86_LOCAL_APIC
-static void hpwdt_check_nmi_decoding(struct pci_dev *dev)
-{
-	/*
-	 * If nmi_watchdog is turned off then we can turn on
-	 * our nmi decoding capability.
-	 */
-	hpwdt_nmi_decoding = 1;
-}
-#else
-static void hpwdt_check_nmi_decoding(struct pci_dev *dev)
-{
-	dev_warn(&dev->dev, "NMI decoding is disabled. "
-		"Your kernel does not support a NMI Watchdog.\n");
-}
-#endif /* CONFIG_X86_LOCAL_APIC */
-
-/*
- *	dmi_find_icru
- *
- *	Routine Description:
- *	This function checks whether or not we are on an iCRU-based server.
- *	This check is independent of architecture and needs to be made for
- *	any ProLiant system.
- */
-static void dmi_find_icru(const struct dmi_header *dm, void *dummy)
-{
-	struct smbios_proliant_info *smbios_proliant_ptr;
-
-	if (dm->type == SMBIOS_ICRU_INFORMATION) {
-		smbios_proliant_ptr = (struct smbios_proliant_info *) dm;
-		if (smbios_proliant_ptr->misc_features & 0x01)
-			is_icru = 1;
-		if (smbios_proliant_ptr->misc_features & 0x1400)
-			is_uefi = 1;
-	}
-}
 
 static int hpwdt_init_nmi_decoding(struct pci_dev *dev)
 {
+#ifdef CONFIG_HPWDT_NMI_DECODING
 	int retval;
-
-	/*
-	 * On typical CRU-based systems we need to map that service in
-	 * the BIOS. For 32 bit Operating Systems we need to go through
-	 * the 32 Bit BIOS Service Directory. For 64 bit Operating
-	 * Systems we get that service through SMBIOS.
-	 *
-	 * On systems that support the new iCRU service all we need to
-	 * do is call dmi_walk to get the supported flag value and skip
-	 * the old cru detect code.
-	 */
-	dmi_walk(dmi_find_icru, NULL);
-	if (!is_icru && !is_uefi) {
-
-		/*
-		* We need to map the ROM to get the CRU service.
-		* For 32 bit Operating Systems we need to go through the 32 Bit
-		* BIOS Service Directory
-		* For 64 bit Operating Systems we get that service through SMBIOS.
-		*/
-		retval = detect_cru_service();
-		if (retval < 0) {
-			dev_warn(&dev->dev,
-				"Unable to detect the %d Bit CRU Service.\n",
-				HPWDT_ARCH);
-			return retval;
-		}
-
-		/*
-		* We know this is the only CRU call we need to make so lets keep as
-		* few instructions as possible once the NMI comes in.
-		*/
-		cmn_regs.u1.rah = 0x0D;
-		cmn_regs.u1.ral = 0x02;
-	}
-
 	/*
 	 * Only one function can register for NMI_UNKNOWN
 	 */
@@ -780,45 +316,26 @@ error:
 	dev_warn(&dev->dev,
 		"Unable to register a die notifier (err=%d).\n",
 		retval);
-	if (cru_rom_addr)
-		iounmap(cru_rom_addr);
 	return retval;
+#endif	/* CONFIG_HPWDT_NMI_DECODING */
+	return 0;
 }
 
 static void hpwdt_exit_nmi_decoding(void)
 {
+#ifdef CONFIG_HPWDT_NMI_DECODING
 	unregister_nmi_handler(NMI_UNKNOWN, "hpwdt");
 	unregister_nmi_handler(NMI_SERR, "hpwdt");
 	unregister_nmi_handler(NMI_IO_CHECK, "hpwdt");
-	if (cru_rom_addr)
-		iounmap(cru_rom_addr);
-}
-#else /* !CONFIG_HPWDT_NMI_DECODING */
-static void hpwdt_check_nmi_decoding(struct pci_dev *dev)
-{
-}
-
-static int hpwdt_init_nmi_decoding(struct pci_dev *dev)
-{
-	return 0;
+#endif
 }
 
-static void hpwdt_exit_nmi_decoding(void)
-{
-}
-#endif /* CONFIG_HPWDT_NMI_DECODING */
-
 static int hpwdt_init_one(struct pci_dev *dev,
 					const struct pci_device_id *ent)
 {
 	int retval;
 
 	/*
-	 * Check if we can do NMI decoding or not
-	 */
-	hpwdt_check_nmi_decoding(dev);
-
-	/*
 	 * First let's find out if we are on an iLO2+ server. We will
 	 * not run on a legacy ASM box.
 	 * So we only support the G5 ProLiant servers and higher.
@@ -922,6 +439,6 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 #ifdef CONFIG_HPWDT_NMI_DECODING
 module_param(allow_kdump, int, 0);
 MODULE_PARM_DESC(allow_kdump, "Start a kernel dump after NMI occurs");
-#endif /* !CONFIG_HPWDT_NMI_DECODING */
+#endif /* CONFIG_HPWDT_NMI_DECODING */
 
 module_pci_driver(hpwdt_driver);