* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* This automated bisection report was sent to you on the basis *
* that you may be involved with the breaking commit it has *
* found. No manual investigation has been done to verify it, *
* and the root cause of the problem may be somewhere else. *
* *
* If you do send a fix, please include this trailer: *
* Reported-by: "kernelci.org bot" <[email protected]> *
* *
* Hope this helps! *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
rmk/for-next bisection: boot on ox820-cloudengines-pogoplug-series-3
Summary:
Start: b6c3c42cfda0 ARM: 8938/1: kernel: initialize broadcast hrtimer based clock event device
Details: https://kernelci.org/boot/id/5dcf3f0359b514dc84cf54c8
Plain log: https://storage.kernelci.org//rmk/for-next/v5.4-rc5-26-gb6c3c42cfda0/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/boot-ox820-cloudengines-pogoplug-series-3.txt
HTML log: https://storage.kernelci.org//rmk/for-next/v5.4-rc5-26-gb6c3c42cfda0/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/boot-ox820-cloudengines-pogoplug-series-3.html
Result: ea70bf6e92c5 ARM: 8935/1: decompressor: avoid CP15 barrier instructions in v7 cache setup code
Checks:
revert: PASS
verify: PASS
Parameters:
Tree: rmk
URL: git://git.armlinux.org.uk/~rmk/linux-arm.git
Branch: for-next
Target: ox820-cloudengines-pogoplug-series-3
CPU arch: arm
Lab: lab-baylibre
Compiler: gcc-8
Config: oxnas_v6_defconfig
Test suite: boot
Breaking commit found:
-------------------------------------------------------------------------------
commit ea70bf6e92c5d8cf38c8a077e0eded091c275899
Author: Ard Biesheuvel <[email protected]>
Date: Fri Nov 8 13:46:50 2019 +0100
ARM: 8935/1: decompressor: avoid CP15 barrier instructions in v7 cache setup code
Commit e17b1af96b2afc38e684aa2f1033387e2ed10029
"ARM: 8857/1: efi: enable CP15 DMB instructions before cleaning the cache"
added some explicit handling of the CP15BEN bit in the SCTLR system
register, to ensure that CP15 barrier instructions are enabled, even
if we enter the decompressor via the EFI stub.
However, as it turns out, there are other ways in which we may end up
using CP15 barrier instructions without them being enabled. I.e., when
the decompressor startup code skips the cache_on() initially, we end
up calling cache_clean_flush() with the caches and MMU off, in which
case the CP15BEN bit in SCTLR may not be programmed either. And in
fact, cache_on() itself issues CP15 barrier instructions before actually
enabling them by programming the new SCTLR value (and issuing an ISB)
Since all these routines are specific to v7, let's clean this up by
using the ordinary v7 barrier instructions in the v7 specific cache
handling routines, so that we never rely on the CP15 ones. This also
avoids the issue where a barrier is required between programming SCTLR
and using the CP15 barrier instructions, which would result in two
different kinds of barriers being used in the same function.
Acked-by: Marc Zyngier <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Russell King <[email protected]>
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 95238146b7f2..fe279816b298 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -656,6 +656,21 @@ params: ldr r0, =0x10000100 @ params_phys for RPC
.align
#endif
+ .macro v7dsb
+ ARM( .inst 0xf57ff04f @ v7+ dsb )
+ THUMB( dsb )
+ .endm
+
+ .macro v7dmb
+ ARM( .inst 0xf57ff05f @ v7+ dmb )
+ THUMB( dmb )
+ .endm
+
+ .macro v7isb
+ ARM( .inst 0xf57ff06f @ v7+ isb )
+ THUMB( isb )
+ .endm
+
/*
* Turn on the cache. We need to setup some page tables so that we
* can have both the I and D caches on.
@@ -827,7 +842,7 @@ __armv7_mmu_cache_on:
movne r6, #CB_BITS | 0x02 @ !XN
blne __setup_mmu
mov r0, #0
- mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
+ v7dsb @ drain write buffer
tst r11, #0xf @ VMSA
mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
#endif
@@ -849,11 +864,11 @@ __armv7_mmu_cache_on:
mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
#endif
- mcr p15, 0, r0, c7, c5, 4 @ ISB
+ v7isb
mcr p15, 0, r0, c1, c0, 0 @ load control register
mrc p15, 0, r0, c1, c0, 0 @ and read it back
mov r0, #0
- mcr p15, 0, r0, c7, c5, 4 @ ISB
+ v7isb
mov pc, r12
__fa526_cache_on:
@@ -1154,8 +1169,8 @@ __armv7_mmu_cache_off:
mcr p15, 0, r0, c8, c7, 0 @ invalidate whole TLB
#endif
mcr p15, 0, r0, c7, c5, 6 @ invalidate BTC
- mcr p15, 0, r0, c7, c10, 4 @ DSB
- mcr p15, 0, r0, c7, c5, 4 @ ISB
+ v7dsb
+ v7isb
mov pc, r12
/*
@@ -1218,7 +1233,7 @@ __armv7_mmu_cache_flush:
mcr p15, 0, r10, c7, c14, 0 @ clean+invalidate D
b iflush
hierarchical:
- mcr p15, 0, r10, c7, c10, 5 @ DMB
+ v7dmb
stmfd sp!, {r0-r7, r9-r11}
mrc p15, 1, r0, c0, c0, 1 @ read clidr
ands r3, r0, #0x7000000 @ extract loc from clidr
@@ -1232,7 +1247,7 @@ loop1:
cmp r1, #2 @ see what cache we have at this level
blt skip @ skip if no cache, or just i-cache
mcr p15, 2, r10, c0, c0, 0 @ select current cache level in cssr
- mcr p15, 0, r10, c7, c5, 4 @ isb to sych the new cssr&csidr
+ v7isb @ isb to sych the new cssr&csidr
mrc p15, 1, r1, c0, c0, 0 @ read the new csidr
and r2, r1, #7 @ extract the length of the cache lines
add r2, r2, #4 @ add 4 (line length offset)
@@ -1264,10 +1279,10 @@ finished:
mov r10, #0 @ switch back to cache level 0
mcr p15, 2, r10, c0, c0, 0 @ select current cache level in cssr
iflush:
- mcr p15, 0, r10, c7, c10, 4 @ DSB
+ v7dsb
mcr p15, 0, r10, c7, c5, 0 @ invalidate I+BTB
- mcr p15, 0, r10, c7, c10, 4 @ DSB
- mcr p15, 0, r10, c7, c5, 4 @ ISB
+ v7dsb
+ v7isb
mov pc, lr
__armv5tej_mmu_cache_flush:
-------------------------------------------------------------------------------
Git bisection log:
-------------------------------------------------------------------------------
git bisect start
# good: [cb73737ea1d27181f5c4bfb1288e97f3e8a4abc7] ARM: 8928/1: ARM_ERRATA_775420: Spelling s/date/data/
git bisect good cb73737ea1d27181f5c4bfb1288e97f3e8a4abc7
# bad: [b6c3c42cfda04b0119a0ac46c2a06006f38522d7] ARM: 8938/1: kernel: initialize broadcast hrtimer based clock event device
git bisect bad b6c3c42cfda04b0119a0ac46c2a06006f38522d7
# good: [052e76a31b4a64d7678e270d498e1bc36c342f88] ARM: 8931/1: Add clock_getres entry point
git bisect good 052e76a31b4a64d7678e270d498e1bc36c342f88
# good: [44700c1ea9afeb9c5093dba7794117fda7c5c955] ARM: 8934/1: Revert "efi: enable CP15 DMB instructions before cleaning the cache"
git bisect good 44700c1ea9afeb9c5093dba7794117fda7c5c955
# bad: [7f586a0a683ec37ac25bee24381e24c66dfe32b8] ARM: 8937/1: spectre-v2: remove Brahma-B53 from hardening
git bisect bad 7f586a0a683ec37ac25bee24381e24c66dfe32b8
# bad: [ea70bf6e92c5d8cf38c8a077e0eded091c275899] ARM: 8935/1: decompressor: avoid CP15 barrier instructions in v7 cache setup code
git bisect bad ea70bf6e92c5d8cf38c8a077e0eded091c275899
# first bad commit: [ea70bf6e92c5d8cf38c8a077e0eded091c275899] ARM: 8935/1: decompressor: avoid CP15 barrier instructions in v7 cache setup code
-------------------------------------------------------------------------------
(+ Arnd)
On Sat, 16 Nov 2019 at 05:54, kernelci.org bot <[email protected]> wrote:
>
> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> * This automated bisection report was sent to you on the basis *
> * that you may be involved with the breaking commit it has *
> * found. No manual investigation has been done to verify it, *
> * and the root cause of the problem may be somewhere else. *
> * *
> * If you do send a fix, please include this trailer: *
> * Reported-by: "kernelci.org bot" <[email protected]> *
> * *
> * Hope this helps! *
> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
>
> rmk/for-next bisection: boot on ox820-cloudengines-pogoplug-series-3
>
> Summary:
> Start: b6c3c42cfda0 ARM: 8938/1: kernel: initialize broadcast hrtimer based clock event device
> Details: https://kernelci.org/boot/id/5dcf3f0359b514dc84cf54c8
> Plain log: https://storage.kernelci.org//rmk/for-next/v5.4-rc5-26-gb6c3c42cfda0/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/boot-ox820-cloudengines-pogoplug-series-3.txt
> HTML log: https://storage.kernelci.org//rmk/for-next/v5.4-rc5-26-gb6c3c42cfda0/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/boot-ox820-cloudengines-pogoplug-series-3.html
> Result: ea70bf6e92c5 ARM: 8935/1: decompressor: avoid CP15 barrier instructions in v7 cache setup code
>
OK, so this regression is caused by the fact that the 'armv7' cache
maintenance routines in the decompressor are also used for ARMv6 cores
if they implement the CPUID extension, which I failed to realise when
I sent this patch.
There are roughly three ways to deal with this:
1) add a mask/val match pair for ARM11MPcore and ARM1176 that hardwire
them to the ARMv6 routines, even though they implement the CPUID
extension. This would be very easy, but assumes that those two cores
are the only ones that are affected by this.
2) modify the v7 routines to check for the L1Hvd MMFR1 attribute (in
the flush routine) and for the CP15BEN SCTLR bit (in the on/off
routines), and jump to the respective v6 variants if the CPU turns out
not to support the v7 one.
3) revert the patch, and just enable the CP15 barriers (and issue a v7
barrier) in the v7 on() and flush() routines.
I am leaning towards the latter, since it is the most straightforward,
even though it mixes v7 and cp15 barriers in the same function, but
that was mostly a cosmetic concern anyway.
> Checks:
> revert: PASS
> verify: PASS
>
> Parameters:
> Tree: rmk
> URL: git://git.armlinux.org.uk/~rmk/linux-arm.git
> Branch: for-next
> Target: ox820-cloudengines-pogoplug-series-3
> CPU arch: arm
> Lab: lab-baylibre
> Compiler: gcc-8
> Config: oxnas_v6_defconfig
> Test suite: boot
>
> Breaking commit found:
>
> -------------------------------------------------------------------------------
> commit ea70bf6e92c5d8cf38c8a077e0eded091c275899
> Author: Ard Biesheuvel <[email protected]>
> Date: Fri Nov 8 13:46:50 2019 +0100
>
> ARM: 8935/1: decompressor: avoid CP15 barrier instructions in v7 cache setup code
>
> Commit e17b1af96b2afc38e684aa2f1033387e2ed10029
>
> "ARM: 8857/1: efi: enable CP15 DMB instructions before cleaning the cache"
>
> added some explicit handling of the CP15BEN bit in the SCTLR system
> register, to ensure that CP15 barrier instructions are enabled, even
> if we enter the decompressor via the EFI stub.
>
> However, as it turns out, there are other ways in which we may end up
> using CP15 barrier instructions without them being enabled. I.e., when
> the decompressor startup code skips the cache_on() initially, we end
> up calling cache_clean_flush() with the caches and MMU off, in which
> case the CP15BEN bit in SCTLR may not be programmed either. And in
> fact, cache_on() itself issues CP15 barrier instructions before actually
> enabling them by programming the new SCTLR value (and issuing an ISB)
>
> Since all these routines are specific to v7, let's clean this up by
> using the ordinary v7 barrier instructions in the v7 specific cache
> handling routines, so that we never rely on the CP15 ones. This also
> avoids the issue where a barrier is required between programming SCTLR
> and using the CP15 barrier instructions, which would result in two
> different kinds of barriers being used in the same function.
>
> Acked-by: Marc Zyngier <[email protected]>
> Signed-off-by: Ard Biesheuvel <[email protected]>
> Signed-off-by: Russell King <[email protected]>
>
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index 95238146b7f2..fe279816b298 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -656,6 +656,21 @@ params: ldr r0, =0x10000100 @ params_phys for RPC
> .align
> #endif
>
> + .macro v7dsb
> + ARM( .inst 0xf57ff04f @ v7+ dsb )
> + THUMB( dsb )
> + .endm
> +
> + .macro v7dmb
> + ARM( .inst 0xf57ff05f @ v7+ dmb )
> + THUMB( dmb )
> + .endm
> +
> + .macro v7isb
> + ARM( .inst 0xf57ff06f @ v7+ isb )
> + THUMB( isb )
> + .endm
> +
> /*
> * Turn on the cache. We need to setup some page tables so that we
> * can have both the I and D caches on.
> @@ -827,7 +842,7 @@ __armv7_mmu_cache_on:
> movne r6, #CB_BITS | 0x02 @ !XN
> blne __setup_mmu
> mov r0, #0
> - mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
> + v7dsb @ drain write buffer
> tst r11, #0xf @ VMSA
> mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
> #endif
> @@ -849,11 +864,11 @@ __armv7_mmu_cache_on:
> mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
> #endif
> - mcr p15, 0, r0, c7, c5, 4 @ ISB
> + v7isb
> mcr p15, 0, r0, c1, c0, 0 @ load control register
> mrc p15, 0, r0, c1, c0, 0 @ and read it back
> mov r0, #0
> - mcr p15, 0, r0, c7, c5, 4 @ ISB
> + v7isb
> mov pc, r12
>
> __fa526_cache_on:
> @@ -1154,8 +1169,8 @@ __armv7_mmu_cache_off:
> mcr p15, 0, r0, c8, c7, 0 @ invalidate whole TLB
> #endif
> mcr p15, 0, r0, c7, c5, 6 @ invalidate BTC
> - mcr p15, 0, r0, c7, c10, 4 @ DSB
> - mcr p15, 0, r0, c7, c5, 4 @ ISB
> + v7dsb
> + v7isb
> mov pc, r12
>
> /*
> @@ -1218,7 +1233,7 @@ __armv7_mmu_cache_flush:
> mcr p15, 0, r10, c7, c14, 0 @ clean+invalidate D
> b iflush
> hierarchical:
> - mcr p15, 0, r10, c7, c10, 5 @ DMB
> + v7dmb
> stmfd sp!, {r0-r7, r9-r11}
> mrc p15, 1, r0, c0, c0, 1 @ read clidr
> ands r3, r0, #0x7000000 @ extract loc from clidr
> @@ -1232,7 +1247,7 @@ loop1:
> cmp r1, #2 @ see what cache we have at this level
> blt skip @ skip if no cache, or just i-cache
> mcr p15, 2, r10, c0, c0, 0 @ select current cache level in cssr
> - mcr p15, 0, r10, c7, c5, 4 @ isb to sych the new cssr&csidr
> + v7isb @ isb to sych the new cssr&csidr
> mrc p15, 1, r1, c0, c0, 0 @ read the new csidr
> and r2, r1, #7 @ extract the length of the cache lines
> add r2, r2, #4 @ add 4 (line length offset)
> @@ -1264,10 +1279,10 @@ finished:
> mov r10, #0 @ switch back to cache level 0
> mcr p15, 2, r10, c0, c0, 0 @ select current cache level in cssr
> iflush:
> - mcr p15, 0, r10, c7, c10, 4 @ DSB
> + v7dsb
> mcr p15, 0, r10, c7, c5, 0 @ invalidate I+BTB
> - mcr p15, 0, r10, c7, c10, 4 @ DSB
> - mcr p15, 0, r10, c7, c5, 4 @ ISB
> + v7dsb
> + v7isb
> mov pc, lr
>
> __armv5tej_mmu_cache_flush:
> -------------------------------------------------------------------------------
>
>
> Git bisection log:
>
> -------------------------------------------------------------------------------
> git bisect start
> # good: [cb73737ea1d27181f5c4bfb1288e97f3e8a4abc7] ARM: 8928/1: ARM_ERRATA_775420: Spelling s/date/data/
> git bisect good cb73737ea1d27181f5c4bfb1288e97f3e8a4abc7
> # bad: [b6c3c42cfda04b0119a0ac46c2a06006f38522d7] ARM: 8938/1: kernel: initialize broadcast hrtimer based clock event device
> git bisect bad b6c3c42cfda04b0119a0ac46c2a06006f38522d7
> # good: [052e76a31b4a64d7678e270d498e1bc36c342f88] ARM: 8931/1: Add clock_getres entry point
> git bisect good 052e76a31b4a64d7678e270d498e1bc36c342f88
> # good: [44700c1ea9afeb9c5093dba7794117fda7c5c955] ARM: 8934/1: Revert "efi: enable CP15 DMB instructions before cleaning the cache"
> git bisect good 44700c1ea9afeb9c5093dba7794117fda7c5c955
> # bad: [7f586a0a683ec37ac25bee24381e24c66dfe32b8] ARM: 8937/1: spectre-v2: remove Brahma-B53 from hardening
> git bisect bad 7f586a0a683ec37ac25bee24381e24c66dfe32b8
> # bad: [ea70bf6e92c5d8cf38c8a077e0eded091c275899] ARM: 8935/1: decompressor: avoid CP15 barrier instructions in v7 cache setup code
> git bisect bad ea70bf6e92c5d8cf38c8a077e0eded091c275899
> # first bad commit: [ea70bf6e92c5d8cf38c8a077e0eded091c275899] ARM: 8935/1: decompressor: avoid CP15 barrier instructions in v7 cache setup code
> -------------------------------------------------------------------------------
On Sat, Nov 16, 2019 at 10:26:27AM +0000, Ard Biesheuvel wrote:
> (+ Arnd)
>
> On Sat, 16 Nov 2019 at 05:54, kernelci.org bot <[email protected]> wrote:
> >
> > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> > * This automated bisection report was sent to you on the basis *
> > * that you may be involved with the breaking commit it has *
> > * found. No manual investigation has been done to verify it, *
> > * and the root cause of the problem may be somewhere else. *
> > * *
> > * If you do send a fix, please include this trailer: *
> > * Reported-by: "kernelci.org bot" <[email protected]> *
> > * *
> > * Hope this helps! *
> > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> >
> > rmk/for-next bisection: boot on ox820-cloudengines-pogoplug-series-3
> >
> > Summary:
> > Start: b6c3c42cfda0 ARM: 8938/1: kernel: initialize broadcast hrtimer based clock event device
> > Details: https://kernelci.org/boot/id/5dcf3f0359b514dc84cf54c8
> > Plain log: https://storage.kernelci.org//rmk/for-next/v5.4-rc5-26-gb6c3c42cfda0/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/boot-ox820-cloudengines-pogoplug-series-3.txt
> > HTML log: https://storage.kernelci.org//rmk/for-next/v5.4-rc5-26-gb6c3c42cfda0/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/boot-ox820-cloudengines-pogoplug-series-3.html
> > Result: ea70bf6e92c5 ARM: 8935/1: decompressor: avoid CP15 barrier instructions in v7 cache setup code
> >
>
> OK, so this regression is caused by the fact that the 'armv7' cache
> maintenance routines in the decompressor are also used for ARMv6 cores
> if they implement the CPUID extension, which I failed to realise when
> I sent this patch.
>
> There are roughly three ways to deal with this:
> 1) add a mask/val match pair for ARM11MPcore and ARM1176 that hardwire
> them to the ARMv6 routines, even though they implement the CPUID
> extension. This would be very easy, but assumes that those two cores
> are the only ones that are affected by this.
> 2) modify the v7 routines to check for the L1Hvd MMFR1 attribute (in
> the flush routine) and for the CP15BEN SCTLR bit (in the on/off
> routines), and jump to the respective v6 variants if the CPU turns out
> not to support the v7 one.
> 3) revert the patch, and just enable the CP15 barriers (and issue a v7
> barrier) in the v7 on() and flush() routines.
>
> I am leaning towards the latter, since it is the most straightforward,
> even though it mixes v7 and cp15 barriers in the same function, but
> that was mostly a cosmetic concern anyway.
I'm going to drop the patches - if -rc8 is released tomorrow maybe we
can have a go at solving it next week.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up
On Sat, 16 Nov 2019 10:26:27 +0000
Ard Biesheuvel <[email protected]> wrote:
> (+ Arnd)
>
> On Sat, 16 Nov 2019 at 05:54, kernelci.org bot <[email protected]> wrote:
> >
> > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> > * This automated bisection report was sent to you on the basis *
> > * that you may be involved with the breaking commit it has *
> > * found. No manual investigation has been done to verify it, *
> > * and the root cause of the problem may be somewhere else. *
> > * *
> > * If you do send a fix, please include this trailer: *
> > * Reported-by: "kernelci.org bot" <[email protected]> *
> > * *
> > * Hope this helps! *
> > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> >
> > rmk/for-next bisection: boot on ox820-cloudengines-pogoplug-series-3
> >
> > Summary:
> > Start: b6c3c42cfda0 ARM: 8938/1: kernel: initialize broadcast hrtimer based clock event device
> > Details: https://kernelci.org/boot/id/5dcf3f0359b514dc84cf54c8
> > Plain log: https://storage.kernelci.org//rmk/for-next/v5.4-rc5-26-gb6c3c42cfda0/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/boot-ox820-cloudengines-pogoplug-series-3.txt
> > HTML log: https://storage.kernelci.org//rmk/for-next/v5.4-rc5-26-gb6c3c42cfda0/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/boot-ox820-cloudengines-pogoplug-series-3.html
> > Result: ea70bf6e92c5 ARM: 8935/1: decompressor: avoid CP15 barrier instructions in v7 cache setup code
> >
>
> OK, so this regression is caused by the fact that the 'armv7' cache
> maintenance routines in the decompressor are also used for ARMv6 cores
> if they implement the CPUID extension, which I failed to realise when
> I sent this patch.
Nobody expects the 11MPcore... :-(.
> There are roughly three ways to deal with this:
> 1) add a mask/val match pair for ARM11MPcore and ARM1176 that hardwire
> them to the ARMv6 routines, even though they implement the CPUID
> extension. This would be very easy, but assumes that those two cores
> are the only ones that are affected by this.
> 2) modify the v7 routines to check for the L1Hvd MMFR1 attribute (in
> the flush routine) and for the CP15BEN SCTLR bit (in the on/off
> routines), and jump to the respective v6 variants if the CPU turns out
> not to support the v7 one.
> 3) revert the patch, and just enable the CP15 barriers (and issue a v7
> barrier) in the v7 on() and flush() routines.
>
> I am leaning towards the latter, since it is the most straightforward,
> even though it mixes v7 and cp15 barriers in the same function, but
> that was mostly a cosmetic concern anyway.
A potential alternative is to check for the presence of architected
barriers in a macro (see the hack below). I've given it a go as a 32bit
guest on an A72 box, both as ARM and Thumb, and nothing caught fire. Of
course, it remains to be seen whether it works on a v6 machine (I don't
think I have any left in my zoo -- please don't send me any), and more
importantly whether we want to carry this kind of horror...
M.
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index ec14687aea3c..144de4b08547 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -656,19 +656,40 @@ params: ldr r0, =0x10000100 @ params_phys for RPC
.align
#endif
- .macro v7dsb
+ @ Check for architected barrier instructions
+ @ Branch to the tgt label if v7 barriers are
+ @ not available. Corrupts the tmp register
+ @ as well as the flags.
+ .macro no_v7_barrier, tmp, tgt
+ mrc p15, 0, \tmp, c0, c2, 4 @ ID_ISAR4
+ tst \tmp, #0xf << 16
+ beq \tgt
+ .endm
+
+ @ The following macros will use zreg as a temp
+ @ register, and will zero it after use.
+ .macro __dsb, zreg
+ no_v7_barrier \zreg, .L__dsb\@
ARM( .inst 0xf57ff04f @ v7+ dsb )
THUMB( dsb )
+ mov \zreg, #0
+.L__dsb\@: mcreq p15, 0, \zreg, c7, c10, 4 @ dsb
.endm
- .macro v7dmb
+ .macro __dmb, zreg
+ no_v7_barrier \zreg, .L__dmb\@
ARM( .inst 0xf57ff05f @ v7+ dmb )
THUMB( dmb )
+ mov \zreg, #0
+.L__dmb\@: mcreq p15, 0, \zreg, c7, c10, 5 @ dmb
.endm
- .macro v7isb
+ .macro __isb, zreg
+ no_v7_barrier \zreg, .L__isb\@
ARM( .inst 0xf57ff06f @ v7+ isb )
THUMB( isb )
+ mov \zreg, #0
+.L__isb\@: mcreq p15, 0, \zreg, c7, c5, 4 @ isb
.endm
/*
@@ -841,8 +862,7 @@ __armv7_mmu_cache_on:
tst r11, #0xf @ VMSA
movne r6, #CB_BITS | 0x02 @ !XN
blne __setup_mmu
- mov r0, #0
- v7dsb @ drain write buffer
+ __dsb r0 @ drain write buffer
tst r11, #0xf @ VMSA
mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
#endif
@@ -864,11 +884,10 @@ __armv7_mmu_cache_on:
mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
#endif
- v7isb
+ __isb lr
mcr p15, 0, r0, c1, c0, 0 @ load control register
mrc p15, 0, r0, c1, c0, 0 @ and read it back
- mov r0, #0
- v7isb
+ __isb r0
mov pc, r12
__fa526_cache_on:
@@ -1169,8 +1188,8 @@ __armv7_mmu_cache_off:
mcr p15, 0, r0, c8, c7, 0 @ invalidate whole TLB
#endif
mcr p15, 0, r0, c7, c5, 6 @ invalidate BTC
- v7dsb
- v7isb
+ __dsb r0
+ __isb r0
mov pc, r12
/*
@@ -1233,7 +1252,7 @@ __armv7_mmu_cache_flush:
mcr p15, 0, r10, c7, c14, 0 @ clean+invalidate D
b iflush
hierarchical:
- v7dmb
+ __dmb r10
stmfd sp!, {r0-r7, r9-r11}
mrc p15, 1, r0, c0, c0, 1 @ read clidr
ands r3, r0, #0x7000000 @ extract loc from clidr
@@ -1247,7 +1266,7 @@ loop1:
cmp r1, #2 @ see what cache we have at this level
blt skip @ skip if no cache, or just i-cache
mcr p15, 2, r10, c0, c0, 0 @ select current cache level in cssr
- v7isb @ isb to sych the new cssr&csidr
+ __isb r1 @ isb to sych the new cssr&csidr
mrc p15, 1, r1, c0, c0, 0 @ read the new csidr
and r2, r1, #7 @ extract the length of the cache lines
add r2, r2, #4 @ add 4 (line length offset)
@@ -1279,10 +1298,10 @@ finished:
mov r10, #0 @ switch back to cache level 0
mcr p15, 2, r10, c0, c0, 0 @ select current cache level in cssr
iflush:
- v7dsb
+ __dsb r10
mcr p15, 0, r10, c7, c5, 0 @ invalidate I+BTB
- v7dsb
- v7isb
+ __dsb r10
+ __isb r10
mov pc, lr
__armv5tej_mmu_cache_flush:
--
Jazz is not dead. It just smells funny...
On Sat, 16 Nov 2019 at 13:32, Marc Zyngier <[email protected]> wrote:
>
> On Sat, 16 Nov 2019 10:26:27 +0000
> Ard Biesheuvel <[email protected]> wrote:
>
> > (+ Arnd)
> >
> > On Sat, 16 Nov 2019 at 05:54, kernelci.org bot <[email protected]> wrote:
> > >
> > > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> > > * This automated bisection report was sent to you on the basis *
> > > * that you may be involved with the breaking commit it has *
> > > * found. No manual investigation has been done to verify it, *
> > > * and the root cause of the problem may be somewhere else. *
> > > * *
> > > * If you do send a fix, please include this trailer: *
> > > * Reported-by: "kernelci.org bot" <[email protected]> *
> > > * *
> > > * Hope this helps! *
> > > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> > >
> > > rmk/for-next bisection: boot on ox820-cloudengines-pogoplug-series-3
> > >
> > > Summary:
> > > Start: b6c3c42cfda0 ARM: 8938/1: kernel: initialize broadcast hrtimer based clock event device
> > > Details: https://kernelci.org/boot/id/5dcf3f0359b514dc84cf54c8
> > > Plain log: https://storage.kernelci.org//rmk/for-next/v5.4-rc5-26-gb6c3c42cfda0/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/boot-ox820-cloudengines-pogoplug-series-3.txt
> > > HTML log: https://storage.kernelci.org//rmk/for-next/v5.4-rc5-26-gb6c3c42cfda0/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/boot-ox820-cloudengines-pogoplug-series-3.html
> > > Result: ea70bf6e92c5 ARM: 8935/1: decompressor: avoid CP15 barrier instructions in v7 cache setup code
> > >
> >
> > OK, so this regression is caused by the fact that the 'armv7' cache
> > maintenance routines in the decompressor are also used for ARMv6 cores
> > if they implement the CPUID extension, which I failed to realise when
> > I sent this patch.
>
> Nobody expects the 11MPcore... :-(.
>
Yeah :-)
> > There are roughly three ways to deal with this:
> > 1) add a mask/val match pair for ARM11MPcore and ARM1176 that hardwire
> > them to the ARMv6 routines, even though they implement the CPUID
> > extension. This would be very easy, but assumes that those two cores
> > are the only ones that are affected by this.
> > 2) modify the v7 routines to check for the L1Hvd MMFR1 attribute (in
> > the flush routine) and for the CP15BEN SCTLR bit (in the on/off
> > routines), and jump to the respective v6 variants if the CPU turns out
> > not to support the v7 one.
> > 3) revert the patch, and just enable the CP15 barriers (and issue a v7
> > barrier) in the v7 on() and flush() routines.
> >
> > I am leaning towards the latter, since it is the most straightforward,
> > even though it mixes v7 and cp15 barriers in the same function, but
> > that was mostly a cosmetic concern anyway.
>
> A potential alternative is to check for the presence of architected
> barriers in a macro (see the hack below). I've given it a go as a 32bit
> guest on an A72 box, both as ARM and Thumb, and nothing caught fire. Of
> course, it remains to be seen whether it works on a v6 machine (I don't
> think I have any left in my zoo -- please don't send me any), and more
> importantly whether we want to carry this kind of horror...
>
Thanks.
But as I said, it might be better just to enable the CP15 barriers.
They haven't been removed from the architecture yet, so they are
always supported - we just have to enable them.
>
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index ec14687aea3c..144de4b08547 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -656,19 +656,40 @@ params: ldr r0, =0x10000100 @ params_phys for RPC
> .align
> #endif
>
> - .macro v7dsb
> + @ Check for architected barrier instructions
> + @ Branch to the tgt label if v7 barriers are
> + @ not available. Corrupts the tmp register
> + @ as well as the flags.
> + .macro no_v7_barrier, tmp, tgt
> + mrc p15, 0, \tmp, c0, c2, 4 @ ID_ISAR4
> + tst \tmp, #0xf << 16
> + beq \tgt
> + .endm
> +
> + @ The following macros will use zreg as a temp
> + @ register, and will zero it after use.
> + .macro __dsb, zreg
> + no_v7_barrier \zreg, .L__dsb\@
> ARM( .inst 0xf57ff04f @ v7+ dsb )
> THUMB( dsb )
> + mov \zreg, #0
> +.L__dsb\@: mcreq p15, 0, \zreg, c7, c10, 4 @ dsb
> .endm
>
> - .macro v7dmb
> + .macro __dmb, zreg
> + no_v7_barrier \zreg, .L__dmb\@
> ARM( .inst 0xf57ff05f @ v7+ dmb )
> THUMB( dmb )
> + mov \zreg, #0
> +.L__dmb\@: mcreq p15, 0, \zreg, c7, c10, 5 @ dmb
> .endm
>
> - .macro v7isb
> + .macro __isb, zreg
> + no_v7_barrier \zreg, .L__isb\@
> ARM( .inst 0xf57ff06f @ v7+ isb )
> THUMB( isb )
> + mov \zreg, #0
> +.L__isb\@: mcreq p15, 0, \zreg, c7, c5, 4 @ isb
> .endm
>
> /*
> @@ -841,8 +862,7 @@ __armv7_mmu_cache_on:
> tst r11, #0xf @ VMSA
> movne r6, #CB_BITS | 0x02 @ !XN
> blne __setup_mmu
> - mov r0, #0
> - v7dsb @ drain write buffer
> + __dsb r0 @ drain write buffer
> tst r11, #0xf @ VMSA
> mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
> #endif
> @@ -864,11 +884,10 @@ __armv7_mmu_cache_on:
> mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
> mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
> #endif
> - v7isb
> + __isb lr
> mcr p15, 0, r0, c1, c0, 0 @ load control register
> mrc p15, 0, r0, c1, c0, 0 @ and read it back
> - mov r0, #0
> - v7isb
> + __isb r0
> mov pc, r12
>
> __fa526_cache_on:
> @@ -1169,8 +1188,8 @@ __armv7_mmu_cache_off:
> mcr p15, 0, r0, c8, c7, 0 @ invalidate whole TLB
> #endif
> mcr p15, 0, r0, c7, c5, 6 @ invalidate BTC
> - v7dsb
> - v7isb
> + __dsb r0
> + __isb r0
> mov pc, r12
>
> /*
> @@ -1233,7 +1252,7 @@ __armv7_mmu_cache_flush:
> mcr p15, 0, r10, c7, c14, 0 @ clean+invalidate D
> b iflush
> hierarchical:
> - v7dmb
> + __dmb r10
> stmfd sp!, {r0-r7, r9-r11}
> mrc p15, 1, r0, c0, c0, 1 @ read clidr
> ands r3, r0, #0x7000000 @ extract loc from clidr
> @@ -1247,7 +1266,7 @@ loop1:
> cmp r1, #2 @ see what cache we have at this level
> blt skip @ skip if no cache, or just i-cache
> mcr p15, 2, r10, c0, c0, 0 @ select current cache level in cssr
> - v7isb @ isb to sych the new cssr&csidr
> + __isb r1 @ isb to sych the new cssr&csidr
> mrc p15, 1, r1, c0, c0, 0 @ read the new csidr
> and r2, r1, #7 @ extract the length of the cache lines
> add r2, r2, #4 @ add 4 (line length offset)
> @@ -1279,10 +1298,10 @@ finished:
> mov r10, #0 @ switch back to cache level 0
> mcr p15, 2, r10, c0, c0, 0 @ select current cache level in cssr
> iflush:
> - v7dsb
> + __dsb r10
> mcr p15, 0, r10, c7, c5, 0 @ invalidate I+BTB
> - v7dsb
> - v7isb
> + __dsb r10
> + __isb r10
> mov pc, lr
>
> __armv5tej_mmu_cache_flush:
>
> --
> Jazz is not dead. It just smells funny...
On Sat, 16 Nov 2019 at 11:49, Russell King - ARM Linux admin
<[email protected]> wrote:
>
> On Sat, Nov 16, 2019 at 10:26:27AM +0000, Ard Biesheuvel wrote:
> > (+ Arnd)
> >
> > On Sat, 16 Nov 2019 at 05:54, kernelci.org bot <[email protected]> wrote:
> > >
> > > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> > > * This automated bisection report was sent to you on the basis *
> > > * that you may be involved with the breaking commit it has *
> > > * found. No manual investigation has been done to verify it, *
> > > * and the root cause of the problem may be somewhere else. *
> > > * *
> > > * If you do send a fix, please include this trailer: *
> > > * Reported-by: "kernelci.org bot" <[email protected]> *
> > > * *
> > > * Hope this helps! *
> > > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> > >
> > > rmk/for-next bisection: boot on ox820-cloudengines-pogoplug-series-3
> > >
> > > Summary:
> > > Start: b6c3c42cfda0 ARM: 8938/1: kernel: initialize broadcast hrtimer based clock event device
> > > Details: https://kernelci.org/boot/id/5dcf3f0359b514dc84cf54c8
> > > Plain log: https://storage.kernelci.org//rmk/for-next/v5.4-rc5-26-gb6c3c42cfda0/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/boot-ox820-cloudengines-pogoplug-series-3.txt
> > > HTML log: https://storage.kernelci.org//rmk/for-next/v5.4-rc5-26-gb6c3c42cfda0/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/boot-ox820-cloudengines-pogoplug-series-3.html
> > > Result: ea70bf6e92c5 ARM: 8935/1: decompressor: avoid CP15 barrier instructions in v7 cache setup code
> > >
> >
> > OK, so this regression is caused by the fact that the 'armv7' cache
> > maintenance routines in the decompressor are also used for ARMv6 cores
> > if they implement the CPUID extension, which I failed to realise when
> > I sent this patch.
> >
> > There are roughly three ways to deal with this:
> > 1) add a mask/val match pair for ARM11MPcore and ARM1176 that hardwire
> > them to the ARMv6 routines, even though they implement the CPUID
> > extension. This would be very easy, but assumes that those two cores
> > are the only ones that are affected by this.
> > 2) modify the v7 routines to check for the L1Hvd MMFR1 attribute (in
> > the flush routine) and for the CP15BEN SCTLR bit (in the on/off
> > routines), and jump to the respective v6 variants if the CPU turns out
> > not to support the v7 one.
> > 3) revert the patch, and just enable the CP15 barriers (and issue a v7
> > barrier) in the v7 on() and flush() routines.
> >
> > I am leaning towards the latter, since it is the most straightforward,
> > even though it mixes v7 and cp15 barriers in the same function, but
> > that was mostly a cosmetic concern anyway.
>
> I'm going to drop the patches - if -rc8 is released tomorrow maybe we
> can have a go at solving it next week.
>
Fair enough.