From f994d99cf140dbb637e49882891c89b3fd84becd Mon Sep 17 00:00:00 2001 From: Hans Rosenfeld Date: Wed, 6 Apr 2011 18:06:43 +0200 Subject: x86-32, fpu: Fix FPU exception handling on non-SSE systems On 32bit systems without SSE (that is, they use FSAVE/FRSTOR for FPU context switches), FPU exceptions in user mode cause Oopses, BUGs, recursive faults and other nasty things: fpu exception: 0000 [#1] last sysfs file: /sys/power/state Modules linked in: psmouse evdev pcspkr serio_raw [last unloaded: scsi_wait_scan] Pid: 1638, comm: fxsave-32-excep Not tainted 2.6.35-07798-g58a992b-dirty #633 VP3-596B-DD/VT82C597 EIP: 0060:[] EFLAGS: 00010202 CPU: 0 EIP is at math_error+0x1b4/0x1c8 EAX: 00000003 EBX: cf9be7e0 ECX: 00000000 EDX: cf9c5c00 ESI: cf9d9fb4 EDI: c1372db3 EBP: 00000010 ESP: cf9d9f1c DS: 007b ES: 007b FS: 0000 GS: 00e0 SS: 0068 Process fxsave-32-excep (pid: 1638, ti=cf9d8000 task=cf9be7e0 task.ti=cf9d8000) Stack: 00000000 00000301 00000004 00000000 00000000 cf9d3000 cf9da8f0 00000001 <0> 00000004 cf9b6b60 c1019a6b c1019a79 00000020 00000242 000001b6 cf9c5380 <0> cf806b40 cf791880 00000000 00000282 00000282 c108a213 00000020 cf9c5380 Call Trace: [] ? need_resched+0x11/0x1a [] ? should_resched+0x5/0x1f [] ? do_sys_open+0xbd/0xc7 [] ? do_sys_open+0xbd/0xc7 [] ? do_coprocessor_error+0x0/0x11 [] ? error_code+0x65/0x70 Code: a8 20 74 30 c7 44 24 0c 06 00 03 00 8d 54 24 04 89 d9 b8 08 00 00 00 e8 9b 6d 02 00 eb 16 8b 93 5c 02 00 00 eb 05 e9 04 ff ff ff <9b> dd 32 9b e9 16 ff ff ff 81 c4 84 00 00 00 5b 5e 5f 5d c3 c6 EIP: [] math_error+0x1b4/0x1c8 SS:ESP 0068:cf9d9f1c This usually continues in slight variations until the system is reset. This bug was introduced by commit 58a992b9cbaf449aeebd3575c3695a9eb5d95b5e: x86-32, fpu: Rewrite fpu_save_init() Signed-off-by: Hans Rosenfeld Link: http://lkml.kernel.org/r/1302106003-366952-1-git-send-email-hans.rosenfeld@amd.com Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/i387.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h index ef328901c802..c9e09ea05644 100644 --- a/arch/x86/include/asm/i387.h +++ b/arch/x86/include/asm/i387.h @@ -237,7 +237,7 @@ static inline void fpu_save_init(struct fpu *fpu) } else if (use_fxsr()) { fpu_fxsave(fpu); } else { - asm volatile("fsave %[fx]; fwait" + asm volatile("fnsave %[fx]; fwait" : [fx] "=m" (fpu->state->fsave)); return; } -- cgit v1.2.3