| Message ID | 20150105125943.GC19655@pd.tnic (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Jan 5, 2015 at 4:59 AM, Borislav Petkov <bp@alien8.de> wrote: > 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 Do you have context tracking on? > >> 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@amacapital.net> >> --- >> 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. Thanks! I assume that's in the historical tree? [...] > > --- > > [ 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) That's really weird. The only thing I can think of is that somehow we returned to user mode without enabling interrupts. This leads me to wonder: why do we save eflags in the R11 pt_regs slot? This seems entirely backwards, not to mention that it accounts for two instructions in each of FIXUP_TOP_OF_STACK and RESTORE_TOP_OF_STACK for no apparently reason whatsoever. Can you send the full output from syscall_exit_regs_64 from here: https://gitorious.org/linux-test-utils/linux-clock-tests/source/34884122b6ebe81d9b96e3e5128b6d6d95082c6e: with the patch applied (assuming it even gets that far for you)? I see results like: [NOTE] syscall ffff: orig RCX = 1 ss = 2b orig_ss = 6b flags = 217 orig_flags = 217 which seems fine. Are you seeing this with the whole series applied or with only this patch? --Andy > [ 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. > --
On Mon, Jan 05, 2015 at 12:31:15PM -0800, Andy Lutomirski wrote: > Do you have context tracking on? Yap, it is enabled for whatever reason: CONFIG_CONTEXT_TRACKING=y CONFIG_CONTEXT_TRACKING_FORCE=y CONFIG_HAVE_CONTEXT_TRACKING=y > I assume that's in the historical tree? Yeah. > > [ 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) > > That's really weird. The only thing I can think of is that somehow we > returned to user mode without enabling interrupts. Right, considering FIXUP_TOP_OF_STACK is used in a bunch of cases in entry_64.S, no wonder it corrupts something. > This leads me to wonder: why do we save eflags in the R11 pt_regs > slot? That: "If executed in 64-bit mode, SYSRET loads the lower-32 RFLAGS bits from R11[31:0] and clears the upper 32 RFLAGS bits." > This seems entirely backwards, not to mention that it accounts for two > instructions in each of FIXUP_TOP_OF_STACK and RESTORE_TOP_OF_STACK > for no apparently reason whatsoever. > Can you send the full output from syscall_exit_regs_64 from here: > > https://gitorious.org/linux-test-utils/linux-clock-tests/source/34884122b6ebe81d9b96e3e5128b6d6d95082c6e: > > with the patch applied (assuming it even gets that far for you)? I > see results like: > > [NOTE] syscall ffff: orig RCX = 1 ss = 2b orig_ss = 6b flags = > 217 orig_flags = 217 > > which seems fine. ./syscall_exit_regs_64 [OK] int80 ffff: AX = ffffffffffffffda [OK] int80 40000000: AX = ffffffffffffffda [OK] syscall ffff: RCX = 400962 RIP = 400962 [OK] syscall ffff: AX = ffffffffffffffda [NOTE] syscall ffff: orig RCX = 1 ss = 2b orig_ss = 6b flags = 217 orig_flags = 217 [OK] syscall 40000000: RCX = 400962 RIP = 400962 [FAIL] syscall 40000000: AX = fffffffffffffff7 [NOTE] syscall 40000000: orig RCX = 1 ss = 2b orig_ss = 6b flags = 217 orig_flags = 217 [OK] syscall(ffff): ret = -1, errno = 38 > Are you seeing this with the whole series applied or with only this patch? I applied this patch only and started seeing those. Then I booted in the previous kernel and tried to repro but it didn't trigger. I'll try hammering on the kernel *without* your patch to see whether I can trigger it somehow...
On Jan 6, 2015 7:34 AM, "Borislav Petkov" <bp@alien8.de> wrote: > > On Mon, Jan 05, 2015 at 12:31:15PM -0800, Andy Lutomirski wrote: > > Do you have context tracking on? > > Yap, it is enabled for whatever reason: > CONFIG_CONTEXT_TRACKING=y > CONFIG_CONTEXT_TRACKING_FORCE=y > CONFIG_HAVE_CONTEXT_TRACKING=y I'll boot a kernel like this on bare metal and see what shakes loose. > > > I assume that's in the historical tree? > > Yeah. > > > > [ 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) > > > > That's really weird. The only thing I can think of is that somehow we > > returned to user mode without enabling interrupts. > > Right, considering FIXUP_TOP_OF_STACK is used in a bunch of cases in > entry_64.S, no wonder it corrupts something. > > > This leads me to wonder: why do we save eflags in the R11 pt_regs > > slot? > > That: "If executed in 64-bit mode, SYSRET loads the lower-32 RFLAGS bits > from R11[31:0] and clears the upper 32 RFLAGS bits." Sure, but the code would be simpler if we shoved that value in the EFLAGS slot. > > > This seems entirely backwards, not to mention that it accounts for two > > instructions in each of FIXUP_TOP_OF_STACK and RESTORE_TOP_OF_STACK > > for no apparently reason whatsoever. > > > Can you send the full output from syscall_exit_regs_64 from here: > > > > https://gitorious.org/linux-test-utils/linux-clock-tests/source/34884122b6ebe81d9b96e3e5128b6d6d95082c6e: > > > > with the patch applied (assuming it even gets that far for you)? I > > see results like: > > > > [NOTE] syscall ffff: orig RCX = 1 ss = 2b orig_ss = 6b flags = > > 217 orig_flags = 217 > > > > which seems fine. > > ./syscall_exit_regs_64 > [OK] int80 ffff: AX = ffffffffffffffda > [OK] int80 40000000: AX = ffffffffffffffda > [OK] syscall ffff: RCX = 400962 RIP = 400962 > [OK] syscall ffff: AX = ffffffffffffffda > [NOTE] syscall ffff: orig RCX = 1 ss = 2b orig_ss = 6b flags = 217 orig_flags = 217 > [OK] syscall 40000000: RCX = 400962 RIP = 400962 > [FAIL] syscall 40000000: AX = fffffffffffffff7 > [NOTE] syscall 40000000: orig RCX = 1 ss = 2b orig_ss = 6b flags = 217 orig_flags = 217 > [OK] syscall(ffff): ret = -1, errno = 38 > > > Are you seeing this with the whole series applied or with only this patch? > > I applied this patch only and started seeing those. Then I booted in the > previous kernel and tried to repro but it didn't trigger. > > I'll try hammering on the kernel *without* your patch to see whether I > can trigger it somehow... Hmm. I added and pushed a test for fork, but that didn't turn anything up. And I don't see any bugs in the code. I booted 3.18 plus this patch with context tracking forced on on my laptop, and something seems to have gone wrong. --Andy > > -- > Regards/Gruss, > Boris. > > Sent from a fat crate under my desk. Formatting is fine. > -- -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jan 06, 2015 at 10:43:57AM -0800, Andy Lutomirski wrote: > Sure, but the code would be simpler if we shoved that value in the > EFLAGS slot. There probably is some reason for that but it's not like we can change it :-) > Hmm. I added and pushed a test for fork, but that didn't turn > anything up. And I don't see any bugs in the code. > > I booted 3.18 plus this patch with context tracking forced on on my > laptop, and something seems to have gone wrong. Well, I ran it on -rc2 + tip/master and it did trigger sporadically yesterday but was unable to trigger something today. I'll redo the whole games tomorrow.
On Tue, Jan 06, 2015 at 08:00:41PM +0100, Borislav Petkov wrote:
> I'll redo the whole games tomorrow.
Ok I can't reproduce today either. Let's ascribe it to this particular
test box being funny or something in 3.19-rcs.
We can look at it if it happens again.
Thanks.
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@suse.cz> * - * $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