Re: [PATCH 1/3] x86_64,entry: Fix RCX for traced syscalls
From: Borislav Petkov
Date: Mon Jan 05 2015 - 07:59:53 EST
On Fri, Nov 07, 2014 at 03:58:17PM -0800, Andy Lutomirski wrote:
> The int_ret_from_sys_call and syscall tracing code disagrees with
> the sysret path as to the value of RCX.
>
> The Intel SDM, the AMD APM, and my laptop all agree that sysret
> returns with RCX == RIP. The syscall tracing code does not respect
> this property.
>
> For example, this program:
>
> int main()
> {
> extern const char syscall_rip[];
> unsigned long rcx = 1;
> unsigned long orig_rcx = rcx;
> asm ("mov $-1, %%eax\n\t"
> "syscall\n\t"
> "syscall_rip:"
> : "+c" (rcx) : : "r11");
> printf("syscall: RCX = %lX RIP = %lX orig RCX = %lx\n",
> rcx, (unsigned long)syscall_rip, orig_rcx);
> return 0;
> }
>
> prints:
> syscall: RCX = 400556 RIP = 400556 orig RCX = 1
>
> Running it under strace gives this instead:
> syscall: RCX = FFFFFFFFFFFFFFFF RIP = 400556 orig RCX = 1
I can trigger the same even without tracing it:
syscall: RCX = FFFFFFFFFFFFFFFF RIP = 40052C orig RCX = 1
> This changes FIXUP_TOP_OF_STACK to match sysret, causing the test to
> show RCX == RIP even under strace.
>
> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
> ---
> arch/x86/kernel/entry_64.S | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
> index df088bb03fb3..3710b8241945 100644
> --- a/arch/x86/kernel/entry_64.S
> +++ b/arch/x86/kernel/entry_64.S
> @@ -143,7 +143,8 @@ ENDPROC(native_usergs_sysret64)
> movq \tmp,RSP+\offset(%rsp)
> movq $__USER_DS,SS+\offset(%rsp)
> movq $__USER_CS,CS+\offset(%rsp)
> - movq $-1,RCX+\offset(%rsp)
> + movq RIP+\offset(%rsp),\tmp /* get rip */
> + movq \tmp,RCX+\offset(%rsp) /* copy it to rcx as sysret would do */
> movq R11+\offset(%rsp),\tmp /* get eflags */
> movq \tmp,EFLAGS+\offset(%rsp)
> .endm
> --
For some reason this patch is causing ata resets on by box, see the
end of this mail. So something's not kosher yet. If I boot the kernel
without it, it all seems ok.
Btw, this change got introduced in 2002 where it used to return rIP in
%rcx before, but it got changed to return -1 for rIP for some reason.
commit af53c7a2c81399b805b6d4eff887401a5e50feef
Author: Andi Kleen <ak@xxxxxx>
Date: Fri Apr 19 20:23:17 2002 -0700
[PATCH] x86-64 architecture specific sync for 2.5.8
This patch brings 2.5.8 in sync with the x86-64 2.4 development tree again
(excluding device drivers)
It has lots of bug fixes and enhancements. It only touches architecture
specific files.
...
diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 6b98b90891f4..16c6e3faf5a7 100644
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -5,7 +5,7 @@
* Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
* Copyright (C) 2000 Pavel Machek <pavel@xxxxxxx>
*
- * $Id: entry.S,v 1.66 2001/11/11 17:47:47 ak Exp $
+ * $Id$
*/
/*
@@ -39,8 +39,7 @@
#include <asm/msr.h>
#include <asm/unistd.h>
#include <asm/thread_info.h>
-
-#define RIP_SYMBOL_NAME(x) x(%rip)
+#include <asm/hw_irq.h>
.code64
@@ -67,8 +66,7 @@
movq \tmp,RSP(%rsp)
movq $__USER_DS,SS(%rsp)
movq $__USER_CS,CS(%rsp)
- movq RCX(%rsp),\tmp /* get return address */
- movq \tmp,RIP(%rsp)
+ movq $-1,RCX(%rsp)
movq R11(%rsp),\tmp /* get eflags */
movq \tmp,EFLAGS(%rsp)
.endm
@@ -76,8 +74,6 @@
.macro RESTORE_TOP_OF_STACK tmp,offset=0
movq RSP-\offset(%rsp),\tmp
movq \tmp,PDAREF(pda_oldrsp)
- movq RIP-\offset(%rsp),\tmp
- movq \tmp,RCX-\offset(%rsp)
movq EFLAGS-\offset(%rsp),\tmp
movq \tmp,R11-\offset(%rsp)
.endm
---
[ 180.059170] ata1.00: exception Emask 0x0 SAct 0x7fffffff SErr 0x0 action 0x6 frozen
[ 180.066873] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.072158] ata1.00: cmd 61/08:00:a8:ac:d9/00:00:23:00:00/40 tag 0 ncq 4096 out
[ 180.072158] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.086912] ata1.00: status: { DRDY }
[ 180.090591] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.095846] ata1.00: cmd 61/08:08:18:ae:d9/00:00:23:00:00/40 tag 1 ncq 4096 out
[ 180.095846] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.110603] ata1.00: status: { DRDY }
[ 180.114283] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.119539] ata1.00: cmd 61/10:10:f0:b1:d9/00:00:23:00:00/40 tag 2 ncq 8192 out
[ 180.119539] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.134292] ata1.00: status: { DRDY }
[ 180.137973] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.143226] ata1.00: cmd 61/08:18:00:98:18/00:00:1d:00:00/40 tag 3 ncq 4096 out
[ 180.143226] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.158105] ata1.00: status: { DRDY }
[ 180.161809] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.167071] ata1.00: cmd 61/10:20:18:98:18/00:00:1d:00:00/40 tag 4 ncq 8192 out
[ 180.167071] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.181822] ata1.00: status: { DRDY }
[ 180.185503] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.190756] ata1.00: cmd 61/a0:28:e0:7c:5d/25:00:1d:00:00/40 tag 5 ncq 4931584 out
[ 180.190756] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.205770] ata1.00: status: { DRDY }
[ 180.209448] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.214692] ata1.00: cmd 61/80:30:80:a2:5d/4a:00:1d:00:00/40 tag 6 ncq 9764864 out
[ 180.214692] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.229701] ata1.00: status: { DRDY }
[ 180.233381] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.238631] ata1.00: cmd 61/08:38:00:ed:5d/22:00:1d:00:00/40 tag 7 ncq 4460544 out
[ 180.238631] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.253647] ata1.00: status: { DRDY }
[ 180.257321] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.262576] ata1.00: cmd 61/08:40:38:b8:18/00:00:1d:00:00/40 tag 8 ncq 4096 out
[ 180.262576] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.277321] ata1.00: status: { DRDY }
[ 180.281007] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.286263] ata1.00: cmd 61/10:48:78:b8:18/00:00:1d:00:00/40 tag 9 ncq 8192 out
[ 180.286263] res 40/00:01:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.301013] ata1.00: status: { DRDY }
[ 180.304693] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.309947] ata1.00: cmd 61/08:50:60:98:d8/00:00:1d:00:00/40 tag 10 ncq 4096 out
[ 180.309947] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.324781] ata1.00: status: { DRDY }
[ 180.328461] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.333713] ata1.00: cmd 61/08:58:18:f8:a1/00:00:20:00:00/40 tag 11 ncq 4096 out
[ 180.333713] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.348550] ata1.00: status: { DRDY }
[ 180.352235] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.357484] ata1.00: cmd 61/08:60:00:88:a0/00:00:20:00:00/40 tag 12 ncq 4096 out
[ 180.357484] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.372318] ata1.00: status: { DRDY }
[ 180.375997] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.381251] ata1.00: cmd 61/48:68:c8:ac:dc/00:00:22:00:00/40 tag 13 ncq 36864 out
[ 180.381251] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.396203] ata1.00: status: { DRDY }
[ 180.399882] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.405134] ata1.00: cmd 61/08:70:40:c8:9d/00:00:20:00:00/40 tag 14 ncq 4096 out
[ 180.405134] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.419993] ata1.00: status: { DRDY }
[ 180.423674] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.428920] ata1.00: cmd 61/08:78:58:a7:9c/00:00:20:00:00/40 tag 15 ncq 4096 out
[ 180.428920] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.443989] ata1.00: status: { DRDY }
[ 180.447892] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.453367] ata1.00: cmd 61/08:80:28:c5:dd/00:00:25:00:00/40 tag 16 ncq 4096 out
[ 180.453367] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.469053] ata1.00: status: { DRDY }
[ 180.472950] ata1.00: failed command: READ FPDMA QUEUED
[ 180.478330] ata1.00: cmd 60/20:88:00:42:3c/00:00:1d:00:00/40 tag 17 ncq 16384 in
[ 180.478330] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.494011] ata1.00: status: { DRDY }
[ 180.497910] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.503378] ata1.00: cmd 61/10:90:80:98:d8/00:00:23:00:00/40 tag 18 ncq 8192 out
[ 180.503378] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.519072] ata1.00: status: { DRDY }
[ 180.522970] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.528434] ata1.00: cmd 61/08:98:88:99:d8/00:00:23:00:00/40 tag 19 ncq 4096 out
[ 180.528434] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.544106] ata1.00: status: { DRDY }
[ 180.547997] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.553462] ata1.00: cmd 61/08:a0:c8:99:d8/00:00:23:00:00/40 tag 20 ncq 4096 out
[ 180.553462] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.569137] ata1.00: status: { DRDY }
[ 180.573030] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.578508] ata1.00: cmd 61/08:a8:e0:9c:d8/00:00:23:00:00/40 tag 21 ncq 4096 out
[ 180.578508] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.594221] ata1.00: status: { DRDY }
[ 180.598126] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.603591] ata1.00: cmd 61/10:b0:18:9f:d8/00:00:23:00:00/40 tag 22 ncq 8192 out
[ 180.603591] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.619266] ata1.00: status: { DRDY }
[ 180.623157] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.628614] ata1.00: cmd 61/08:b8:78:b2:d8/00:00:23:00:00/40 tag 23 ncq 4096 out
[ 180.628614] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.644286] ata1.00: status: { DRDY }
[ 180.648178] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.653642] ata1.00: cmd 61/08:c0:b8:a3:d9/00:00:23:00:00/40 tag 24 ncq 4096 out
[ 180.653642] res 40/00:01:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.669316] ata1.00: status: { DRDY }
[ 180.673205] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.678667] ata1.00: cmd 61/08:c8:00:a5:d9/00:00:23:00:00/40 tag 25 ncq 4096 out
[ 180.678667] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.694340] ata1.00: status: { DRDY }
[ 180.698231] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.703690] ata1.00: cmd 61/08:d0:78:a9:d9/00:00:23:00:00/40 tag 26 ncq 4096 out
[ 180.703690] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.719368] ata1.00: status: { DRDY }
[ 180.723258] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.728720] ata1.00: cmd 61/08:d8:10:aa:d9/00:00:23:00:00/40 tag 27 ncq 4096 out
[ 180.728720] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.744390] ata1.00: status: { DRDY }
[ 180.748276] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.753737] ata1.00: cmd 61/08:e0:20:aa:d9/00:00:23:00:00/40 tag 28 ncq 4096 out
[ 180.753737] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.769414] ata1.00: status: { DRDY }
[ 180.773303] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.778760] ata1.00: cmd 61/10:e8:20:ab:d9/00:00:23:00:00/40 tag 29 ncq 8192 out
[ 180.778760] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.794433] ata1.00: status: { DRDY }
[ 180.798323] ata1.00: failed command: WRITE FPDMA QUEUED
[ 180.803785] ata1.00: cmd 61/08:f0:90:ac:d9/00:00:23:00:00/40 tag 30 ncq 4096 out
[ 180.803785] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 180.819455] ata1.00: status: { DRDY }
[ 180.823358] ata1: hard resetting link
[ 181.131630] ata1: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[ 181.140035] ata1.00: configured for UDMA/133
[ 181.144549] ata1.00: device reported invalid CHS sector 0
[ 181.150207] ata1.00: device reported invalid CHS sector 0
[ 181.155843] ata1.00: device reported invalid CHS sector 0
[ 181.161481] ata1.00: device reported invalid CHS sector 0
[ 181.167147] ata1.00: device reported invalid CHS sector 0
[ 181.172782] ata1.00: device reported invalid CHS sector 0
[ 181.178407] ata1.00: device reported invalid CHS sector 0
[ 181.184033] ata1.00: device reported invalid CHS sector 0
[ 181.189655] ata1.00: device reported invalid CHS sector 0
[ 181.195267] ata1.00: device reported invalid CHS sector 0
[ 181.200882] ata1.00: device reported invalid CHS sector 0
[ 181.206489] ata1.00: device reported invalid CHS sector 0
[ 181.212107] ata1.00: device reported invalid CHS sector 0
[ 181.217720] ata1.00: device reported invalid CHS sector 0
[ 181.223326] ata1.00: device reported invalid CHS sector 0
[ 181.228936] ata1.00: device reported invalid CHS sector 0
[ 181.234533] ata1.00: device reported invalid CHS sector 0
[ 181.240134] ata1.00: device reported invalid CHS sector 0
[ 181.245726] ata1.00: device reported invalid CHS sector 0
[ 181.251323] ata1.00: device reported invalid CHS sector 0
[ 181.256913] ata1.00: device reported invalid CHS sector 0
[ 181.262505] ata1.00: device reported invalid CHS sector 0
[ 181.268087] ata1.00: device reported invalid CHS sector 0
[ 181.273672] ata1.00: device reported invalid CHS sector 0
[ 181.279257] ata1.00: device reported invalid CHS sector 0
[ 181.284836] ata1.00: device reported invalid CHS sector 0
[ 181.290416] ata1.00: device reported invalid CHS sector 0
[ 181.295988] ata1.00: device reported invalid CHS sector 0
[ 181.301571] ata1.00: device reported invalid CHS sector 0
[ 181.307139] ata1.00: device reported invalid CHS sector 0
[ 181.312708] ata1.00: device reported invalid CHS sector 0
[ 181.318426] ata1: EH complete
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
--
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