X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=arch%2Fx86%2Fkernel%2Ftraps.c;h=20542b1a788a9a7e5f07758a852ba9e13991a6a0;hb=c7ed1048ba6b082a8b03d28202e669db5b87eda1;hp=446c9ef8cfc32b68d77d4429128b3c794b3fc069;hpb=cdbe3bf418c1d25a4dca046bafbe846b841699aa;p=mirror_ubuntu-bionic-kernel.git

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 446c9ef8cfc3..20542b1a788a 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -58,6 +58,7 @@
 #include <asm/alternative.h>
 #include <asm/fpu/xstate.h>
 #include <asm/trace/mpx.h>
+#include <asm/nospec-branch.h>
 #include <asm/mpx.h>
 #include <asm/vm86.h>
 #include <asm/umip.h>
@@ -181,7 +182,7 @@ int fixup_bug(struct pt_regs *regs, int trapnr)
 		break;
 
 	case BUG_TRAP_TYPE_WARN:
-		regs->ip += LEN_UD0;
+		regs->ip += LEN_UD2;
 		return 1;
 	}
 
@@ -386,6 +387,13 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 		regs->ip = (unsigned long)general_protection;
 		regs->sp = (unsigned long)&gpregs->orig_ax;
 
+		/*
+		 * This situation can be triggered by userspace via
+		 * modify_ldt(2) and the return does not take the regular
+		 * user space exit, so a CPU buffer clear is required when
+		 * MDS mitigation is enabled.
+		 */
+		mds_user_clear_cpu_buffers();
 		return;
 	}
 #endif
@@ -577,7 +585,6 @@ do_general_protection(struct pt_regs *regs, long error_code)
 }
 NOKPROBE_SYMBOL(do_general_protection);
 
-/* May run on IST stack. */
 dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
 {
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -592,6 +599,13 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
 	if (poke_int3_handler(regs))
 		return;
 
+	/*
+	 * Use ist_enter despite the fact that we don't use an IST stack.
+	 * We can be called from a kprobe in non-CONTEXT_KERNEL kernel
+	 * mode or even during context tracking state changes.
+	 *
+	 * This means that we can't schedule.  That's okay.
+	 */
 	ist_enter(regs);
 	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
@@ -609,15 +623,10 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
 			SIGTRAP) == NOTIFY_STOP)
 		goto exit;
 
-	/*
-	 * Let others (NMI) know that the debug stack is in use
-	 * as we may switch to the interrupt stack.
-	 */
-	debug_stack_usage_inc();
 	cond_local_irq_enable(regs);
 	do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
 	cond_local_irq_disable(regs);
-	debug_stack_usage_dec();
+
 exit:
 	ist_exit(regs);
 }
@@ -833,16 +842,18 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr)
 	char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
 						"simd exception";
 
-	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
-		return;
 	cond_local_irq_enable(regs);
 
 	if (!user_mode(regs)) {
-		if (!fixup_exception(regs, trapnr)) {
-			task->thread.error_code = error_code;
-			task->thread.trap_nr = trapnr;
+		if (fixup_exception(regs, trapnr))
+			return;
+
+		task->thread.error_code = error_code;
+		task->thread.trap_nr = trapnr;
+
+		if (notify_die(DIE_TRAP, str, regs, error_code,
+					trapnr, SIGFPE) != NOTIFY_STOP)
 			die(str, regs, error_code);
-		}
 		return;
 	}