Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Ingo Molnar:
 "Misc fixes: a SYSRET single-stepping fix, a dmi-scan robustization
  fix, a reboot quirk and a kgdb fixlet"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  kgdb/x86: Fix reporting of 'si' in kgdb on x86_64
  x86/asm/entry/64: Disable opportunistic SYSRET if regs->flags has TF set
  x86/reboot: Add ASRock Q1900DC-ITX mainboard reboot quirk
  MAINTAINERS: Change the x86 microcode loader maintainer
  firmware: dmi_scan: Prevent dmi_num integer overflow

5 files changed, 35 insertions, 20 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index ac976acd9841..efbcb50e4969 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -637,8 +637,7 @@ F:      drivers/gpu/drm/radeon/radeon_kfd.h
 F:      include/uapi/linux/kfd_ioctl.h
 
 AMD MICROCODE UPDATE SUPPORT
-M:      Andreas Herrmann <herrmann.der.user@googlemail.com>
-L:      amd64-microcode@amd64.org
+M:      Borislav Petkov <bp@alien8.de>
 S:      Maintained
 F:      arch/x86/kernel/cpu/microcode/amd*
 
@@ -5095,7 +5094,7 @@ S:	Supported
 F:      drivers/platform/x86/intel_menlow.c
 
 INTEL IA32 MICROCODE UPDATE SUPPORT
-M:      Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
+M:      Borislav Petkov <bp@alien8.de>
 S:      Maintained
 F:      arch/x86/kernel/cpu/microcode/core*
 F:      arch/x86/kernel/cpu/microcode/intel*
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 2babb393915e..f0095a76c182 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -799,7 +799,21 @@ retint_swapgs:		/* return to user-space */
         cmpq %r11,(EFLAGS-ARGOFFSET)(%rsp)      /* R11 == RFLAGS */
         jne opportunistic_sysret_failed
 
-        testq $X86_EFLAGS_RF,%r11               /* sysret can't restore RF */
+        /*
+         * SYSRET can't restore RF.  SYSRET can restore TF, but unlike IRET,
+         * restoring TF results in a trap from userspace immediately after
+         * SYSRET.  This would cause an infinite loop whenever #DB happens
+         * with register state that satisfies the opportunistic SYSRET
+         * conditions.  For example, single-stepping this user code:
+         *
+         *           movq $stuck_here,%rcx
+         *           pushfq
+         *           popq %r11
+         *   stuck_here:
+         *
+         * would never get past 'stuck_here'.
+         */
+        testq $(X86_EFLAGS_RF|X86_EFLAGS_TF), %r11
         jnz opportunistic_sysret_failed
 
         /* nothing to check for RSP */
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 7ec1d5f8d283..25ecd56cefa8 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -72,7 +72,7 @@ struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
         { "bx", 8, offsetof(struct pt_regs, bx) },
         { "cx", 8, offsetof(struct pt_regs, cx) },
         { "dx", 8, offsetof(struct pt_regs, dx) },
-        { "si", 8, offsetof(struct pt_regs, dx) },
+        { "si", 8, offsetof(struct pt_regs, si) },
         { "di", 8, offsetof(struct pt_regs, di) },
         { "bp", 8, offsetof(struct pt_regs, bp) },
         { "sp", 8, offsetof(struct pt_regs, sp) },
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index bae6c609888e..86db4bcd7ce5 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -183,6 +183,16 @@ static struct dmi_system_id __initdata reboot_dmi_table[] = {
                 },
         },
 
+        /* ASRock */
+        {       /* Handle problems with rebooting on ASRock Q1900DC-ITX */
+                .callback = set_pci_reboot,
+                .ident = "ASRock Q1900DC-ITX",
+                .matches = {
+                        DMI_MATCH(DMI_BOARD_VENDOR, "ASRock"),
+                        DMI_MATCH(DMI_BOARD_NAME, "Q1900DC-ITX"),
+                },
+        },
+
         /* ASUS */
         {       /* Handle problems with rebooting on ASUS P4S800 */
                 .callback = set_bios_reboot,
diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 69fac068669f..2eebd28b4c40 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -86,10 +86,13 @@ static void dmi_table(u8 *buf, u32 len, int num,
         int i = 0;
 
         /*
-         *      Stop when we see all the items the table claimed to have
-         *      OR we run off the end of the table (also happens)
+         * Stop when we have seen all the items the table claimed to have
+         * (SMBIOS < 3.0 only) OR we reach an end-of-table marker OR we run
+         * off the end of the table (should never happen but sometimes does
+         * on bogus implementations.)
          */
-        while ((i < num) && (data - buf + sizeof(struct dmi_header)) <= len) {
+        while ((!num || i < num) &&
+               (data - buf + sizeof(struct dmi_header)) <= len) {
                 const struct dmi_header *dm = (const struct dmi_header *)data;
 
                 /*
@@ -529,21 +532,10 @@ static int __init dmi_smbios3_present(const u8 *buf)
         if (memcmp(buf, "_SM3_", 5) == 0 &&
             buf[6] < 32 && dmi_checksum(buf, buf[6])) {
                 dmi_ver = get_unaligned_be16(buf + 7);
+                dmi_num = 0;                    /* No longer specified */
                 dmi_len = get_unaligned_le32(buf + 12);
                 dmi_base = get_unaligned_le64(buf + 16);
 
-                /*
-                 * The 64-bit SMBIOS 3.0 entry point no longer has a field
-                 * containing the number of structures present in the table.
-                 * Instead, it defines the table size as a maximum size, and
-                 * relies on the end-of-table structure type (#127) to be used
-                 * to signal the end of the table.
-                 * So let's define dmi_num as an upper bound as well: each
-                 * structure has a 4 byte header, so dmi_len / 4 is an upper
-                 * bound for the number of structures in the table.
-                 */
-                dmi_num = dmi_len / 4;
-
                 if (dmi_walk_early(dmi_decode) == 0) {
                         pr_info("SMBIOS %d.%d present.\n",
                                 dmi_ver >> 8, dmi_ver & 0xFF);