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| author |   Christophe Leroy <christophe.leroy@c-s.fr> | 2017-07-12 12:08:49 +0200 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2017-08-15 22:55:53 +1000 |
| commit | 0eb0d2e77dedcce40674100556f2327d0a4b29db (patch) | |
| tree | 238dad4ea424a53f15aedf80591b3b434d77b41f /arch/powerpc/kernel/entry_32.S | |
| parent | powerpc/8xx: Remove macro that checks kernel address (diff) | |
| download | linux-dev-0eb0d2e77dedcce40674100556f2327d0a4b29db.tar.xz linux-dev-0eb0d2e77dedcce40674100556f2327d0a4b29db.zip | |
powerpc/32: Avoid risk of unrecoverable TLBmiss inside entry_32.S
By default, the 8xx pins an ITLB on the first 8M of memory in order
to avoid any ITLB miss on kernel code.
However, with some debug functions like DEBUG_PAGEALLOC and
DEBUG_RODATA, pinning TLBs is contradictory.
In order to avoid any ITLB miss in a critical section without pinning
TLBs, we have to ensure that there is no page boundary crossed between
the setup of a new value in SRR0/SRR1 and the associated RFI.
The functions modifying srr0/srr1 are all located in setup_32.S.
They are spread over almost 4kbytes.
The patch forces a 12 bits (4kbytes) alignment for those
functions. This garanties that the functions remain in a
single 4k page.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/entry_32.S')
| -rw-r--r-- | arch/powerpc/kernel/entry_32.S | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index b14bf7def2e2..e780e1fbf6c2 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -43,6 +43,13 @@ #define LOAD_MSR_KERNEL(r, x) li r,(x) #endif +/* + * Align to 4k in order to ensure that all functions modyfing srr0/srr1 + * fit into one page in order to not encounter a TLB miss between the + * modification of srr0/srr1 and the associated rfi. + */ + .align 12 + #ifdef CONFIG_BOOKE .globl mcheck_transfer_to_handler mcheck_transfer_to_handler: |