[PATCH 2/3] arm: add early_ioremap support
Rob Herring
robherring2 at gmail.com
Tue May 6 15:58:06 PDT 2014
From: Mark Salter <msalter at redhat.com>
This patch uses the generic early_ioremap code to implement
early_ioremap for ARM. The ARM-specific bits come mostly from
an earlier patch from Leif Lindholm <leif.lindholm at linaro.org>
here:
https://lkml.org/lkml/2013/10/3/279
Signed-off-by: Mark Salter <msalter at redhat.com>
Tested-by: Leif Lindholm <leif.lindholm at linaro.org>
Acked-by: Catalin Marinas <catalin.marinas at arm.com>
[robh: minor re-work in prep for permanent mappings. Fix bug in page
table allocation size. Rework CONFIG_MMU dependency.]
Signed-off-by: Rob Herring <robh at kernel.org>
---
arch/arm/Kconfig | 11 ++++++
arch/arm/include/asm/Kbuild | 1 +
arch/arm/include/asm/fixmap.h | 21 ++++++++++
arch/arm/include/asm/io.h | 1 +
arch/arm/kernel/setup.c | 2 +
arch/arm/mm/Makefile | 2 +
arch/arm/mm/early_ioremap.c | 90 +++++++++++++++++++++++++++++++++++++++++++
arch/arm/mm/mmu.c | 2 +
8 files changed, 130 insertions(+)
create mode 100644 arch/arm/mm/early_ioremap.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index db3c541..b33c68b 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1891,6 +1891,17 @@ config UACCESS_WITH_MEMCPY
However, if the CPU data cache is using a write-allocate mode,
this option is unlikely to provide any performance gain.
+config EARLY_IOREMAP
+ bool "Provide early_ioremap() support for kernel initialization"
+ depends on MMU
+ select GENERIC_EARLY_IOREMAP
+ help
+ Provide a mechanism for kernel initialisation code to temporarily
+ map, in a highmem-agnostic way, memory pages in before ioremap()
+ and friends are available (before paging_init() has run). It uses
+ the same virtual memory range as kmap so all early mappings must
+ be unmapped before paging_init() is called.
+
config SECCOMP
bool
prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/arm/include/asm/Kbuild b/arch/arm/include/asm/Kbuild
index 23e728e..ec64b55 100644
--- a/arch/arm/include/asm/Kbuild
+++ b/arch/arm/include/asm/Kbuild
@@ -4,6 +4,7 @@ generic-y += auxvec.h
generic-y += bitsperlong.h
generic-y += cputime.h
generic-y += current.h
+generic-y += early_ioremap.h
generic-y += emergency-restart.h
generic-y += errno.h
generic-y += exec.h
diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index 68ea615..e36020c 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -21,8 +21,29 @@ enum fixed_addresses {
FIX_KMAP_BEGIN,
FIX_KMAP_END = (FIXADDR_TOP - FIXADDR_START) >> PAGE_SHIFT,
__end_of_fixed_addresses
+/*
+ * 224 temporary boot-time mappings, used by early_ioremap(),
+ * before ioremap() is functional.
+ *
+ * (P)re-using the FIXADDR region, which is used for highmem
+ * later on, and statically aligned to 1MB.
+ */
+#define NR_FIX_BTMAPS 32
+#define FIX_BTMAPS_SLOTS 7
+#define TOTAL_FIX_BTMAPS (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS - FIX_KMAP_BEGIN)
+#define FIX_BTMAP_END FIX_KMAP_BEGIN
+#define FIX_BTMAP_BEGIN (FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1)
};
+#define FIXMAP_PAGE_COMMON (L_PTE_YOUNG | L_PTE_PRESENT | L_PTE_XN)
+
+#define FIXMAP_PAGE_NORMAL (FIXMAP_PAGE_COMMON | L_PTE_MT_WRITEBACK)
+#define FIXMAP_PAGE_IO (FIXMAP_PAGE_COMMON | L_PTE_MT_DEV_SHARED | L_PTE_SHARED | L_PTE_DIRTY)
+#define FIXMAP_PAGE_NOCACHE FIXMAP_PAGE_IO
+
+extern void __early_set_fixmap(enum fixed_addresses idx,
+ phys_addr_t phys, pgprot_t flags);
+
#include <asm-generic/fixmap.h>
#endif
diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index 8aa4cca..637e0cd 100644
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -28,6 +28,7 @@
#include <asm/byteorder.h>
#include <asm/memory.h>
#include <asm-generic/pci_iomap.h>
+#include <asm/early_ioremap.h>
#include <xen/xen.h>
/*
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 50e198c..7882f04 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -30,6 +30,7 @@
#include <linux/bug.h>
#include <linux/compiler.h>
#include <linux/sort.h>
+#include <linux/io.h>
#include <asm/unified.h>
#include <asm/cp15.h>
@@ -883,6 +884,7 @@ void __init setup_arch(char **cmdline_p)
const struct machine_desc *mdesc;
setup_processor();
+ early_ioremap_init();
mdesc = setup_machine_fdt(__atags_pointer);
if (!mdesc)
mdesc = setup_machine_tags(__atags_pointer, __machine_arch_type);
diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile
index 7f39ce2..c6b7b5e 100644
--- a/arch/arm/mm/Makefile
+++ b/arch/arm/mm/Makefile
@@ -12,6 +12,8 @@ ifneq ($(CONFIG_MMU),y)
obj-y += nommu.o
endif
+obj-$(CONFIG_EARLY_IOREMAP) += early_ioremap.o
+
obj-$(CONFIG_ARM_PTDUMP) += dump.o
obj-$(CONFIG_MODULES) += proc-syms.o
diff --git a/arch/arm/mm/early_ioremap.c b/arch/arm/mm/early_ioremap.c
new file mode 100644
index 0000000..0258a20
--- /dev/null
+++ b/arch/arm/mm/early_ioremap.c
@@ -0,0 +1,90 @@
+/*
+ * early_ioremap() support for ARM
+ *
+ * Based on existing support in arch/x86/mm/ioremap.c
+ *
+ * Restrictions: currently only functional before paging_init()
+ */
+
+#include <linux/init.h>
+#include <linux/io.h>
+
+#include <asm/fixmap.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+
+#include <asm/mach/map.h>
+
+static pte_t bm_pte[PTRS_PER_PTE + PTE_HWTABLE_PTRS]
+ __aligned(PTE_HWTABLE_OFF + PTE_HWTABLE_SIZE) __initdata;
+
+static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)
+{
+ unsigned int index = pgd_index(addr);
+ pgd_t *pgd = cpu_get_pgd() + index;
+ pud_t *pud = pud_offset(pgd, addr);
+ pmd_t *pmd = pmd_offset(pud, addr);
+
+ return pmd;
+}
+
+static inline pte_t * __init early_ioremap_pte(unsigned long addr)
+{
+ return &bm_pte[pte_index(addr)];
+}
+
+void __init early_ioremap_init(void)
+{
+ pmd_t *pmd;
+
+ pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
+
+ pmd_populate_kernel(NULL, pmd, bm_pte);
+
+ /*
+ * Make sure we don't span multiple pmds.
+ */
+ BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT)
+ != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT));
+
+ if (pmd != early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END))) {
+ WARN_ON(1);
+ pr_warn("pmd %p != %p\n",
+ pmd, early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END)));
+ pr_warn("fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n",
+ fix_to_virt(FIX_BTMAP_BEGIN));
+ pr_warn("fix_to_virt(FIX_BTMAP_END): %08lx\n",
+ fix_to_virt(FIX_BTMAP_END));
+ pr_warn("FIX_BTMAP_END: %d\n", FIX_BTMAP_END);
+ pr_warn("FIX_BTMAP_BEGIN: %d\n", FIX_BTMAP_BEGIN);
+ }
+
+ early_ioremap_setup();
+}
+
+void __init __early_set_fixmap(enum fixed_addresses idx,
+ phys_addr_t phys, pgprot_t flags)
+{
+ unsigned long addr = __fix_to_virt(idx);
+ pte_t *pte;
+ u64 desc;
+
+ if (idx > FIX_KMAP_END) {
+ BUG();
+ return;
+ }
+ pte = early_ioremap_pte(addr);
+
+ if (pgprot_val(flags))
+ set_pte_at(NULL, addr, pte, pfn_pte(phys >> PAGE_SHIFT, flags));
+ else
+ pte_clear(NULL, addr, pte);
+ flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+ desc = *pte;
+}
+
+void __init early_ioremap_shutdown(void)
+{
+ pmd_clear(early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN)));
+}
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index b68c6b2..9576f87 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -35,6 +35,7 @@
#include <asm/mach/arch.h>
#include <asm/mach/map.h>
#include <asm/mach/pci.h>
+#include <asm/early_ioremap.h>
#include "mm.h"
#include "tcm.h"
@@ -1508,6 +1509,7 @@ void __init paging_init(const struct machine_desc *mdesc)
prepare_page_table();
map_lowmem();
dma_contiguous_remap();
+ early_ioremap_reset();
devicemaps_init(mdesc);
kmap_init();
tcm_init();
--
1.9.1
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