2011-04-05 17:26:53

by Hans Rosenfeld

Subject: [PATCH] x86-32, fpu: unbreak FPU exceptions on systems without SSE

On 32bit systems without SSE, FPU exceptions in user mode cause Oopses,
BUGs, recursive faults and other nasty things.

This was caused by commit 58a992b9cbaf449aeebd3575c3695a9eb5d95b5e:
x86-32, fpu: Rewrite fpu_save_init()
---
arch/x86/include/asm/i387.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index ef32890..c9e09ea 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;
}
--
1.5.6.5

2011-04-06 16:07:07

by Hans Rosenfeld

Subject: [PATCH] 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:[<c1003527>] 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:
[<c1019a6b>] ? need_resched+0x11/0x1a
[<c1019a79>] ? should_resched+0x5/0x1f
[<c108a213>] ? do_sys_open+0xbd/0xc7
[<c108a213>] ? do_sys_open+0xbd/0xc7
[<c100353b>] ? do_coprocessor_error+0x0/0x11
[<c12d5965>] ? 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: [<c1003527>] 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 <[email protected]>
---
arch/x86/include/asm/i387.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index ef32890..c9e09ea 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;
}
--
1.5.6.5

2011-04-07 00:46:13

by Hans Rosenfeld

Subject: [tip:x86/urgent] x86-32, fpu: Fix FPU exception handling on non-SSE systems

Commit-ID: f994d99cf140dbb637e49882891c89b3fd84becd
Gitweb: http://git.kernel.org/tip/f994d99cf140dbb637e49882891c89b3fd84becd
Author: Hans Rosenfeld <[email protected]>
AuthorDate: Wed, 6 Apr 2011 18:06:43 +0200
Committer: H. Peter Anvin <[email protected]>
CommitDate: Wed, 6 Apr 2011 16:53:01 -0700

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:[<c1003527>] 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:
[<c1019a6b>] ? need_resched+0x11/0x1a
[<c1019a79>] ? should_resched+0x5/0x1f
[<c108a213>] ? do_sys_open+0xbd/0xc7
[<c108a213>] ? do_sys_open+0xbd/0xc7
[<c100353b>] ? do_coprocessor_error+0x0/0x11
[<c12d5965>] ? 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: [<c1003527>] 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 <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: H. Peter Anvin <[email protected]>
---
arch/x86/include/asm/i387.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index ef32890..c9e09ea 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;
}