It has odd semantics, and it's only applicable (AFAICS) to #GP and #PF.
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
---
arch/x86/include/asm/traps.h | 6 ++++++
arch/x86/kernel/traps.c | 2 ++
arch/x86/mm/extable.c | 14 --------------
arch/x86/mm/fault.c | 19 +++++++++++++++++++
4 files changed, 27 insertions(+), 14 deletions(-)
diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h
index 88eae2a..55521de 100644
--- a/arch/x86/include/asm/traps.h
+++ b/arch/x86/include/asm/traps.h
@@ -89,6 +89,12 @@ asmlinkage void smp_thermal_interrupt(void);
asmlinkage void mce_threshold_interrupt(void);
#endif
+#ifdef CONFIG_PNPBIOS
+extern void fixup_pnpbios_exception(struct pt_regs *regs);
+#else
+static inline void fixup_pnpbios_exception(struct pt_regs *regs) {}
+#endif
+
/* Interrupts/Exceptions */
enum {
X86_TRAP_DE = 0, /* 0, Divide-by-zero */
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 68bda7a..8647670 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -275,6 +275,8 @@ do_general_protection(struct pt_regs *regs, long error_code)
tsk = current;
if (!user_mode(regs)) {
+ fixup_pnpbios_exception(regs); /* Might not return */
+
if (fixup_exception(regs))
goto exit;
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index 903ec1e..82e4ae8 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -19,20 +19,6 @@ int fixup_exception(struct pt_regs *regs)
const struct exception_table_entry *fixup;
unsigned long new_ip;
-#ifdef CONFIG_PNPBIOS
- if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) {
- extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp;
- extern u32 pnp_bios_is_utter_crap;
- pnp_bios_is_utter_crap = 1;
- printk(KERN_CRIT "PNPBIOS fault.. attempting recovery.\n");
- __asm__ volatile(
- "movl %0, %%esp\n\t"
- "jmp *%1\n\t"
- : : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip));
- panic("do_trap: can't hit this");
- }
-#endif
-
fixup = search_exception_tables(regs->ip);
if (fixup) {
new_ip = ex_fixup_addr(fixup);
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 0e88336..58afb50 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -569,6 +569,23 @@ static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
return 0;
}
+#ifdef CONFIG_PNPBIOS
+void fixup_pnpbios_exception(struct pt_regs *regs)
+{
+ if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) {
+ extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp;
+ extern u32 pnp_bios_is_utter_crap;
+ pnp_bios_is_utter_crap = 1;
+ printk(KERN_CRIT "PNPBIOS fault.. attempting recovery.\n");
+ __asm__ volatile(
+ "movl %0, %%esp\n\t"
+ "jmp *%1\n\t"
+ : : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip));
+ panic("do_trap: can't hit this");
+ }
+}
+#endif
+
static const char nx_warning[] = KERN_CRIT
"kernel tried to execute NX-protected page - exploit attempt? (uid: %d)\n";
@@ -636,6 +653,8 @@ no_context(struct pt_regs *regs, unsigned long error_code,
unsigned long flags;
int sig;
+ fixup_pnpbios_exception(regs); /* Might not return */
+
/* Are we prepared to handle this kernel fault? */
if (fixup_exception(regs)) {
if (current_thread_info()->sig_on_uaccess_error && signal) {
--
1.8.1.4
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