Commit aa49f204 authored by Jann Horn's avatar Jann Horn Committed by Borislav Petkov
Browse files

x86/dumpstack: Introduce die_addr() for die() with #GP fault address 



Split __die() into __die_header() and __die_body(). This allows inserting
extra information below the header line that initiates the bug report.

Introduce a new function die_addr() that behaves like die(), but is for
faults only and uses __die_header() and __die_body() so that a future
commit can print extra information after the header line.

 [ bp: Comment the KASAN-specific usage of gp_addr. ]

Signed-off-by: default avatarJann Horn <jannh@google.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: kasan-dev@googlegroups.com
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191218231150.12139-3-jannh@google.com
parent 59c1dcbe

arch/x86/include/asm/kdebug.h

+1 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ enum show_regs_mode { 
};



extern void die(const char *, struct pt_regs *,long);

void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr);

extern int __must_check __die(const char *, struct pt_regs *, long);

extern void show_stack_regs(struct pt_regs *regs);

extern void __show_regs(struct pt_regs *regs, enum show_regs_mode);

arch/x86/kernel/dumpstack.c

+23 −1
Original line number Diff line number Diff line
@@ -365,7 +365,7 @@ void oops_end(unsigned long flags, struct pt_regs *regs, int signr) 
}

NOKPROBE_SYMBOL(oops_end);



int __die(const char *str, struct pt_regs *regs, long err)

static void __die_header(const char *str, struct pt_regs *regs, long err)

{

	const char *pr = "";
@@ -384,7 +384,11 @@ int __die(const char *str, struct pt_regs *regs, long err) 
	       IS_ENABLED(CONFIG_KASAN)   ? " KASAN"           : "",

	       IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?

	       (boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");

}

NOKPROBE_SYMBOL(__die_header);



static int __die_body(const char *str, struct pt_regs *regs, long err)

{

	show_regs(regs);

	print_modules();
@@ -394,6 +398,13 @@ int __die(const char *str, struct pt_regs *regs, long err) 


	return 0;

}

NOKPROBE_SYMBOL(__die_body);



int __die(const char *str, struct pt_regs *regs, long err)

{

	__die_header(str, regs, err);

	return __die_body(str, regs, err);

}

NOKPROBE_SYMBOL(__die);



/*
@@ -410,6 +421,17 @@ void die(const char *str, struct pt_regs *regs, long err) 
	oops_end(flags, regs, sig);

}



void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr)

{

	unsigned long flags = oops_begin();

	int sig = SIGSEGV;



	__die_header(str, regs, err);

	if (__die_body(str, regs, err))

		sig = 0;

	oops_end(flags, regs, sig);

}



void show_regs(struct pt_regs *regs)

{

	show_regs_print_info(KERN_DEFAULT);

arch/x86/kernel/traps.c

+8 −1
Original line number Diff line number Diff line
@@ -619,7 +619,14 @@ dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code) 
				 "maybe for address",

				 gp_addr);



		die(desc, regs, error_code);

		/*

		 * KASAN is interested only in the non-canonical case, clear it

		 * otherwise.

		 */

		if (hint != GP_NON_CANONICAL)

			gp_addr = 0;



		die_addr(desc, regs, error_code, gp_addr);

		return;

	}

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