[RFC PATCH kernel] powerpc: Fix early setup to make early_ioremap work
aik at ozlabs.ru
Thu May 20 15:52:38 AEST 2021
On 20/05/2021 15:46, Christophe Leroy wrote:
> Le 20/05/2021 à 05:29, Alexey Kardashevskiy a écrit :
>> The immediate problem is that after
>> 0bd3f9e953bd ("powerpc/legacy_serial: Use early_ioremap()")
>> the kernel silently reboots. The reason is that early_ioremap() returns
>> broken addresses as it uses slot_virt array which initialized with
>> offsets from FIXADDR_TOP == IOREMAP_END+FIXADDR_SIZE ==
>> KERN_IO_END- FIXADDR_SIZ + FIXADDR_SIZE == __kernel_io_end which is 0
>> when early_ioremap_setup() is called. __kernel_io_end is initialized
>> little bit later in early_init_mmu().
>> This fixes the initialization by swapping early_ioremap_setup and
> Hum ... Chris tested it on a T2080RDB, that must be a book3e.
> So we missed it. I guess your fix is right.
>> This also fixes IOREMAP_END to use FIXADDR_SIZE defined just next to it,
>> seems to make sense, unless there is some weird logic with redefining
>> FIXADDR_SIZE as the compiling goes.
> Well, I don't think the order of defines matters, the change should be
> kept out of the fix.
When I see this:
#define IOREMAP_END (KERN_IO_END - FIXADDR_SIZE)
#define FIXADDR_SIZE SZ_32M
... I have to think harder what FIXADDR_SIZE was in the first macro and
in what order the preprocessor expands them.
> But if you want it anyway, then I'd suggest to move it before
> IOREMAP_BASE in order to keep the 3 IOREMAP_xxx together.
Up to Michael, I guess.
>> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> Reviewed-by: Christophe Leroy <christophe.leroy at csgroup.eu>
>> arch/powerpc/include/asm/book3s/64/pgtable.h | 2 +-
>> arch/powerpc/kernel/setup_64.c | 3 ++-
>> 2 files changed, 3 insertions(+), 2 deletions(-)
>> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h
>> index a666d561b44d..54a06129794b 100644
>> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
>> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
>> @@ -325,8 +325,8 @@ extern unsigned long pci_io_base;
>> #define PHB_IO_END (KERN_IO_START + FULL_IO_SIZE)
>> #define IOREMAP_BASE (PHB_IO_END)
>> #define IOREMAP_START (ioremap_bot)
>> -#define IOREMAP_END (KERN_IO_END - FIXADDR_SIZE)
>> #define FIXADDR_SIZE SZ_32M
>> +#define IOREMAP_END (KERN_IO_END - FIXADDR_SIZE)
>> /* Advertise special mapping type for AGP */
>> #define HAVE_PAGE_AGP
>> diff --git a/arch/powerpc/kernel/setup_64.c
>> index b779d25761cf..ce09fe5debf4 100644
>> --- a/arch/powerpc/kernel/setup_64.c
>> +++ b/arch/powerpc/kernel/setup_64.c
>> @@ -369,11 +369,12 @@ void __init early_setup(unsigned long dt_ptr)
>> - early_ioremap_setup();
>> /* Initialize the hash table or TLB handling */
>> + early_ioremap_setup();
>> * After firmware and early platform setup code has set things up,
>> * we note the SPR values for configurable control/performance
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