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Commit d315760f authored by Tejun Heo's avatar Tejun Heo Committed by Ingo Molnar
Browse files

x86: fix math_emu register frame access 



do_device_not_available() is the handler for #NM and it declares that
it takes a unsigned long and calls math_emu(), which takes a long
argument and surprisingly expects the stack frame starting at the zero
argument would match struct math_emu_info, which isn't true regardless
of configuration in the current code.

This patch makes do_device_not_available() take struct pt_regs like
other exception handlers and initialize struct math_emu_info with
pointer to it and pass pointer to the math_emu_info to math_emulate()
like normal C functions do.  This way, unless gcc makes a copy of
struct pt_regs in do_device_not_available(), the register frame is
correctly accessed regardless of kernel configuration or compiler
used.

This doesn't fix all math_emu problems but it at least gets it
somewhat working.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ae6af41f

arch/x86/include/asm/math_emu.h

+2 −2
Original line number Diff line number Diff line
@@ -11,8 +11,8 @@ 
struct math_emu_info {

	long ___orig_eip;

	union {

		struct pt_regs regs;

		struct kernel_vm86_regs vm86;

		struct pt_regs *regs;

		struct kernel_vm86_regs *vm86;

	};

};

#endif /* _ASM_X86_MATH_EMU_H */

arch/x86/include/asm/traps.h

+2 −2
Original line number Diff line number Diff line
@@ -41,7 +41,7 @@ dotraplinkage void do_int3(struct pt_regs *, long); 
dotraplinkage void do_overflow(struct pt_regs *, long);

dotraplinkage void do_bounds(struct pt_regs *, long);

dotraplinkage void do_invalid_op(struct pt_regs *, long);

dotraplinkage void do_device_not_available(struct pt_regs *, long);

dotraplinkage void do_device_not_available(struct pt_regs);

dotraplinkage void do_coprocessor_segment_overrun(struct pt_regs *, long);

dotraplinkage void do_invalid_TSS(struct pt_regs *, long);

dotraplinkage void do_segment_not_present(struct pt_regs *, long);
@@ -77,7 +77,7 @@ extern int panic_on_unrecovered_nmi; 
extern int kstack_depth_to_print;



void math_error(void __user *);

asmlinkage void math_emulate(long);

void math_emulate(struct math_emu_info *);

#ifdef CONFIG_X86_32

unsigned long patch_espfix_desc(unsigned long, unsigned long);

#else

arch/x86/kernel/traps.c

+9 −6
Original line number Diff line number Diff line
@@ -896,7 +896,7 @@ asmlinkage void math_state_restore(void) 
EXPORT_SYMBOL_GPL(math_state_restore);



#ifndef CONFIG_MATH_EMULATION

asmlinkage void math_emulate(long arg)

void math_emulate(struct math_emu_info *info)

{

	printk(KERN_EMERG

		"math-emulation not enabled and no coprocessor found.\n");
@@ -906,16 +906,19 @@ asmlinkage void math_emulate(long arg) 
}

#endif /* CONFIG_MATH_EMULATION */



dotraplinkage void __kprobes

do_device_not_available(struct pt_regs *regs, long error)

dotraplinkage void __kprobes do_device_not_available(struct pt_regs regs)

{

#ifdef CONFIG_X86_32

	if (read_cr0() & X86_CR0_EM) {

		conditional_sti(regs);

		math_emulate(0);

		struct math_emu_info info = { };



		conditional_sti(&regs);



		info.regs = &regs;

		math_emulate(&info);

	} else {

		math_state_restore(); /* interrupts still off */

		conditional_sti(regs);

		conditional_sti(&regs);

	}

#else

	math_state_restore();

arch/x86/math-emu/fpu_entry.c

+2 −2
Original line number Diff line number Diff line
@@ -131,7 +131,7 @@ u_char emulating = 0; 
static int valid_prefix(u_char *Byte, u_char __user ** fpu_eip,

			overrides * override);



asmlinkage void math_emulate(long arg)

void math_emulate(struct math_emu_info *info)

{

	u_char FPU_modrm, byte1;

	unsigned short code;
@@ -161,7 +161,7 @@ asmlinkage void math_emulate(long arg) 
	RE_ENTRANT_CHECK_ON;

#endif /* RE_ENTRANT_CHECKING */



	SETUP_DATA_AREA(arg);

	FPU_info = info;



	FPU_ORIG_EIP = FPU_EIP;

arch/x86/math-emu/fpu_proto.h

+1 −1
Original line number Diff line number Diff line
@@ -51,7 +51,7 @@ extern void ffreep(void); 
extern void fst_i_(void);

extern void fstp_i(void);

/* fpu_entry.c */

asmlinkage extern void math_emulate(long arg);

extern void math_emulate(struct math_emu_info *info);

extern void math_abort(struct math_emu_info *info, unsigned int signal);

/* fpu_etc.c */

extern void FPU_etc(void);