Allthough kernel text is always mapped with BATs, we still have inittext mapped with pages, so TLB miss handling is required when CONFIG_DEBUG_PAGEALLOC or CONFIG_KFENCE is set.
The final solution should be to set a BAT that also maps inittext but that BAT then needs to be cleared at end of init, and it will require more changes to be able to do it properly.
As DEBUG_PAGEALLOC or KFENCE are debugging, performance is not a big deal so let's fix it simply for now to enable easy stable application.
Reported-by: Maxime Bizon mbizon@freebox.fr Fixes: 035b19a15a98 ("powerpc/32s: Always map kernel text and rodata with BATs") Cc: stable@vger.kernel.org Signed-off-by: Christophe Leroy christophe.leroy@csgroup.eu --- arch/powerpc/kernel/head_book3s_32.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S index 68e5c0a7e99d..2e2a8211b17b 100644 --- a/arch/powerpc/kernel/head_book3s_32.S +++ b/arch/powerpc/kernel/head_book3s_32.S @@ -421,14 +421,14 @@ InstructionTLBMiss: */ /* Get PTE (linux-style) and check access */ mfspr r3,SPRN_IMISS -#ifdef CONFIG_MODULES +#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE) lis r1, TASK_SIZE@h /* check if kernel address */ cmplw 0,r1,r3 #endif mfspr r2, SPRN_SDR1 li r1,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC | _PAGE_USER rlwinm r2, r2, 28, 0xfffff000 -#ifdef CONFIG_MODULES +#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE) bgt- 112f lis r2, (swapper_pg_dir - PAGE_OFFSET)@ha /* if kernel address, use */ li r1,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC
On Tue, 2021-12-07 at 06:10 +0000, Christophe Leroy wrote:
Hello,
With the patch applied and
CONFIG_DEBUG_PAGEALLOC=y CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT=y CONFIG_DEBUG_VM=y
I get tons of this during boot:
[ 0.000000] Dentry cache hash table entries: 262144 (order: 8, 1048576 bytes, linear) [ 0.000000] Inode-cache hash table entries: 131072 (order: 7, 524288 bytes, linear) [ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off [ 0.000000] ------------[ cut here ]------------ [ 0.000000] WARNING: CPU: 0 PID: 0 at arch/powerpc/mm/pgtable.c:194 set_pte_at+0x18/0x160 [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.15.0+ #442 [ 0.000000] NIP: 80015ebc LR: 80016728 CTR: 800166e4 [ 0.000000] REGS: 80751dd0 TRAP: 0700 Not tainted (5.15.0+) [ 0.000000] MSR: 00021032 <ME,IR,DR,RI> CR: 42228882 XER: 20000000 [ 0.000000] [ 0.000000] GPR00: 800b8dc8 80751e80 806c6300 807311d8 807a1000 8ffffe84 80751ea8 00000000 [ 0.000000] GPR08: 007a1591 00000001 007a1180 00000000 42224882 00000000 3ff9c608 3fffd79c [ 0.000000] GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 800166e4 807a2000 [ 0.000000] GPR24: 807a1fff 807311d8 807311d8 807a2000 80768804 00000000 807a1000 007a1180 [ 0.000000] NIP [80015ebc] set_pte_at+0x18/0x160 [ 0.000000] LR [80016728] set_page_attr+0x44/0xc0 [ 0.000000] Call Trace: [ 0.000000] [80751e80] [80058570] console_unlock+0x340/0x428 (unreliable) [ 0.000000] [80751ea0] [00000000] 0x0 [ 0.000000] [80751ec0] [800b8dc8] __apply_to_page_range+0x144/0x2a8 [ 0.000000] [80751f00] [80016918] __kernel_map_pages+0x54/0x64 [ 0.000000] [80751f10] [800cfeb0] __free_pages_ok+0x1b0/0x440 [ 0.000000] [80751f50] [805cfc8c] memblock_free_all+0x1d8/0x274 [ 0.000000] [80751f90] [805c5e0c] mem_init+0x3c/0xd0 [ 0.000000] [80751fb0] [805c0bdc] start_kernel+0x404/0x5c4 [ 0.000000] [80751ff0] [000033f0] 0x33f0 [ 0.000000] Instruction dump: [ 0.000000] 7c630034 83e1000c 5463d97e 7c0803a6 38210010 4e800020 9421ffe0 93e1001c [ 0.000000] 83e60000 81250000 71290001 41820014 <0fe00000> 7c0802a6 93c10018 90010024
Michael, ping.
Le 07/12/2021 à 07:10, Christophe Leroy a écrit :
Allthough kernel text is always mapped with BATs, we still have inittext mapped with pages, so TLB miss handling is required when CONFIG_DEBUG_PAGEALLOC or CONFIG_KFENCE is set.
The final solution should be to set a BAT that also maps inittext but that BAT then needs to be cleared at end of init, and it will require more changes to be able to do it properly.
As DEBUG_PAGEALLOC or KFENCE are debugging, performance is not a big deal so let's fix it simply for now to enable easy stable application.
Reported-by: Maxime Bizon mbizon@freebox.fr Fixes: 035b19a15a98 ("powerpc/32s: Always map kernel text and rodata with BATs") Cc: stable@vger.kernel.org Signed-off-by: Christophe Leroy christophe.leroy@csgroup.eu
arch/powerpc/kernel/head_book3s_32.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S index 68e5c0a7e99d..2e2a8211b17b 100644 --- a/arch/powerpc/kernel/head_book3s_32.S +++ b/arch/powerpc/kernel/head_book3s_32.S @@ -421,14 +421,14 @@ InstructionTLBMiss: */ /* Get PTE (linux-style) and check access */ mfspr r3,SPRN_IMISS -#ifdef CONFIG_MODULES +#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE) lis r1, TASK_SIZE@h /* check if kernel address */ cmplw 0,r1,r3 #endif mfspr r2, SPRN_SDR1 li r1,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC | _PAGE_USER rlwinm r2, r2, 28, 0xfffff000 -#ifdef CONFIG_MODULES +#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE) bgt- 112f lis r2, (swapper_pg_dir - PAGE_OFFSET)@ha /* if kernel address, use */ li r1,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC
On Tue, 7 Dec 2021 06:10:05 +0000, Christophe Leroy wrote:
Allthough kernel text is always mapped with BATs, we still have inittext mapped with pages, so TLB miss handling is required when CONFIG_DEBUG_PAGEALLOC or CONFIG_KFENCE is set.
The final solution should be to set a BAT that also maps inittext but that BAT then needs to be cleared at end of init, and it will require more changes to be able to do it properly.
[...]
Applied to powerpc/fixes.
[1/1] powerpc/603: Fix boot failure with DEBUG_PAGEALLOC and KFENCE https://git.kernel.org/powerpc/c/9bb162fa26ed76031ed0e7dbc77ccea0bf977758
cheers
linux-stable-mirror@lists.linaro.org
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Christophe Leroy -
Maxime Bizon -
Michael Ellerman