diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/entry_64.S | 16 | ||||
| -rw-r--r-- | arch/x86/kernel/kgdb.c | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/reboot.c | 10 |
3 files changed, 26 insertions, 2 deletions
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, |