Re: [PATCH v1 3/4] powerpc: Add support for GENERIC_EARLY_IOREMAP

Christophe Leroy Thu, 12 Sep 2019 09:02:49 -0700



Le 12/09/2019 à 17:50, Aneesh Kumar K.V a écrit :

Christophe Leroy <christophe.le...@c-s.fr> writes:

Le 12/09/2019 à 17:37, Aneesh Kumar K.V a écrit :

Christophe Leroy <christophe.le...@c-s.fr> writes:

Add support for GENERIC_EARLY_IOREMAP.

Let's define 16 slots of 256Kbytes each for early ioremap.

Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
   arch/powerpc/Kconfig              |  1 +
   arch/powerpc/include/asm/Kbuild   |  1 +
   arch/powerpc/include/asm/fixmap.h | 12 ++++++++++++
   arch/powerpc/kernel/setup_32.c    |  3 +++
   arch/powerpc/kernel/setup_64.c    |  3 +++
   5 files changed, 20 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 6a7c797fa9d2..8fe252962518 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -161,6 +161,7 @@ config PPC
        select GENERIC_CMOS_UPDATE
        select GENERIC_CPU_AUTOPROBE
        select GENERIC_CPU_VULNERABILITIES      if PPC_BARRIER_NOSPEC
+       select GENERIC_EARLY_IOREMAP
        select GENERIC_IRQ_SHOW
        select GENERIC_IRQ_SHOW_LEVEL
        select GENERIC_PCI_IOMAP                if PCI
diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild
index 9a1d2fc6ceb7..30829120659c 100644
--- a/arch/powerpc/include/asm/Kbuild
+++ b/arch/powerpc/include/asm/Kbuild
@@ -12,3 +12,4 @@ generic-y += preempt.h
   generic-y += vtime.h
   generic-y += msi.h
   generic-y += simd.h
+generic-y += early_ioremap.h
diff --git a/arch/powerpc/include/asm/fixmap.h 
b/arch/powerpc/include/asm/fixmap.h
index 722289a1d000..d5c4d357bd33 100644
--- a/arch/powerpc/include/asm/fixmap.h
+++ b/arch/powerpc/include/asm/fixmap.h
@@ -15,6 +15,7 @@
   #define _ASM_FIXMAP_H

#ifndef __ASSEMBLY__

+#include <linux/sizes.h>
   #include <asm/page.h>
   #include <asm/pgtable.h>
   #ifdef CONFIG_HIGHMEM
@@ -64,6 +65,14 @@ enum fixed_addresses {
                       FIX_IMMR_SIZE,
   #endif
        /* FIX_PCIE_MCFG, */
+       __end_of_permanent_fixed_addresses,
+
+#define NR_FIX_BTMAPS          (SZ_256K / PAGE_SIZE)
+#define FIX_BTMAPS_SLOTS       16
+#define TOTAL_FIX_BTMAPS       (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
+
+       FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
+       FIX_BTMAP_BEGIN = FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1,
        __end_of_fixed_addresses
   };

@@ -71,6 +80,7 @@ enum fixed_addresses {

   #define FIXADDR_START                (FIXADDR_TOP - __FIXADDR_SIZE)

#define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NCG

+#define FIXMAP_PAGE_IO PAGE_KERNEL_NCG

#include <asm-generic/fixmap.h>@@ -85,5 +95,7 @@ static inline void __set_fixmap(enum fixed_addresses idx,

        map_kernel_page(__fix_to_virt(idx), phys, flags);
   }

+#define __early_set_fixmap __set_fixmap

+
   #endif /* !__ASSEMBLY__ */
   #endif
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index a7541edf0cdb..dcffe927f5b9 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -44,6 +44,7 @@
   #include <asm/asm-prototypes.h>
   #include <asm/kdump.h>
   #include <asm/feature-fixups.h>
+#include <asm/early_ioremap.h>

#include "setup.h"@@ -80,6 +81,8 @@ notrace void __init machine_init(u64 dt_ptr)

        /* Configure static keys first, now that we're relocated. */
        setup_feature_keys();

+ early_ioremap_setup();

+
        /* Enable early debugging if any specified (see udbg.h) */
        udbg_early_init();

diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c

index 44b4c432a273..b85f6a1cc3a1 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -65,6 +65,7 @@
   #include <asm/hw_irq.h>
   #include <asm/feature-fixups.h>
   #include <asm/kup.h>
+#include <asm/early_ioremap.h>

#include "setup.h"@@ -338,6 +339,8 @@ 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();


Can we remove early_ioremap_range() after this?


Yes, once all early callers of ioremap functions are converted to using
early_ioremap()


Why can't we switch the early callers to early_ioremap and print a
warning?

ie,
if (!slab_available()) {
    pr_warn("switch to early_ioremap");
    early_ioremap();
}


Because:
- early_iounmap() requires the size of the area to be freed unlike iounmap()

- early_ioremap() is for ephemeral mappings. All early mapping must begone at the end of init (this is verified bylate_initcall(check_early_ioremap_leak))

Second point means another approach has to be taken for installing earlypermanent mapping, for instance by using fixmaps.


Christophe

Re: [PATCH v1 3/4] powerpc: Add support for GENERIC_EARLY_IOREMAP

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