Re: [RFC PATCH kernel] powerpc: Fix early setup to make early_ioremap work

From
Christophe Leroy <hidden>
Date
2021-05-20 06:03:48
Reply to
Alexey Kardashevskiy, 2021-05-20

Le 20/05/2021 à 07:52, Alexey Kardashevskiy a écrit :

On 20/05/2021 15:46, Christophe Leroy wrote:
quoted

Le 20/05/2021 à 05:29, Alexey Kardashevskiy a écrit :
quoted
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
early_init_mmu.
Hum ... Chris tested it on a T2080RDB, that must be a book3e.

So we missed it. I guess your fix is right.

Oh cool.
I forgot, your patch should include Fixes: tags.

Fixes: 265c3491c4bc ("powerpc: Add support for GENERIC_EARLY_IOREMAP")

If you still change the FIXADDR_SIZE, then it must also have:

Fixes: 9ccba66d4d2a ("powerpc/64: Fix the definition of the fixmap area")
quoted
quoted
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.

quoted
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.

quoted
quoted
Signed-off-by: Alexey Kardashevskiy <redacted>
Reviewed-by: Christophe Leroy <redacted>
quoted
---
  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 b/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 b/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)
      apply_feature_fixups();
      setup_feature_keys();
-    early_ioremap_setup();
      /* Initialize the hash table or TLB handling */
      early_init_mmu();
+    early_ioremap_setup();
+
      /*
       * After firmware and early platform setup code has set things up,
       * we note the SPR values for configurable control/performance
Thread (7 messages) 7 messages, 3 authors, last reply 2021-05-21
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