Commit 36209766 authored by Borislav Petkov's avatar Borislav Petkov
Browse files

x86/traps: Cleanup do_general_protection() 



Hoist the user_mode() case up because it is less code and can be dealt
with up-front like the other special cases UMIP and vm86.

This saves an indentation level for the kernel-mode #GP case and allows
to "unfold" the code more so that it is more readable.

No functional changes.

Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Jann Horn <jannh@google.com>
Cc: x86@kernel.org
parent 2f004eea

arch/x86/kernel/traps.c

+40 −39
Original line number Diff line number Diff line
@@ -567,7 +567,10 @@ static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs, 
dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code)

{

	char desc[sizeof(GPFSTR) + 50 + 2*sizeof(unsigned long) + 1] = GPFSTR;

	enum kernel_gp_hint hint = GP_NO_HINT;

	struct task_struct *tsk;

	unsigned long gp_addr;

	int ret;



	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");

	cond_local_irq_enable(regs);
@@ -584,9 +587,16 @@ dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code) 
	}



	tsk = current;

	if (!user_mode(regs)) {

		enum kernel_gp_hint hint = GP_NO_HINT;

		unsigned long gp_addr;



	if (user_mode(regs)) {

		tsk->thread.error_code = error_code;

		tsk->thread.trap_nr = X86_TRAP_GP;



		show_signal(tsk, SIGSEGV, "", desc, regs, error_code);

		force_sig(SIGSEGV);



		return;

	}



	if (fixup_exception(regs, X86_TRAP_GP, error_code, 0))

		return;
@@ -595,16 +605,16 @@ dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code) 
	tsk->thread.trap_nr = X86_TRAP_GP;



	/*

		 * To be potentially processing a kprobe fault and to

		 * trust the result from kprobe_running(), we have to

		 * be non-preemptible.

	 * To be potentially processing a kprobe fault and to trust the result

	 * from kprobe_running(), we have to be non-preemptible.

	 */

		if (!preemptible() && kprobe_running() &&

	if (!preemptible() &&

	    kprobe_running() &&

	    kprobe_fault_handler(regs, X86_TRAP_GP))

		return;



		if (notify_die(DIE_GPF, desc, regs, error_code,

			       X86_TRAP_GP, SIGSEGV) == NOTIFY_STOP)

	ret = notify_die(DIE_GPF, desc, regs, error_code, X86_TRAP_GP, SIGSEGV);

	if (ret == NOTIFY_STOP)

		return;



	if (error_code)
@@ -614,9 +624,8 @@ dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code) 


	if (hint != GP_NO_HINT)

		snprintf(desc, sizeof(desc), GPFSTR ", %s 0x%lx",

				 (hint == GP_NON_CANONICAL) ?

				 "probably for non-canonical address" :

				 "maybe for address",

			 (hint == GP_NON_CANONICAL) ? "probably for non-canonical address"

						    : "maybe for address",

			 gp_addr);



	/*
@@ -627,15 +636,7 @@ dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code) 
		gp_addr = 0;



	die_addr(desc, regs, error_code, gp_addr);

		return;

	}



	tsk->thread.error_code = error_code;

	tsk->thread.trap_nr = X86_TRAP_GP;



	show_signal(tsk, SIGSEGV, "", desc, regs, error_code);



	force_sig(SIGSEGV);

}

NOKPROBE_SYMBOL(do_general_protection);

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