[PATCH v2 2/2] arm: add early_ioremap support
From: Leif Lindholm
Date: Fri Sep 06 2013 - 05:20:50 EST
This patch adds support for early_ioremap and early_memremap, based
on the existing mechanism in x86. Up to 7 regions of up to 128KB each
can be temporarily mapped in before paging_init, regardless of later
highmem status.
Signed-off-by: Leif Lindholm <leif.lindholm@xxxxxxxxxx>
---
arch/arm/Kconfig | 7 ++
arch/arm/include/asm/fixmap.h | 31 ++++-
arch/arm/include/asm/io.h | 17 +++
arch/arm/kernel/setup.c | 5 +
arch/arm/mm/Makefile | 1 +
arch/arm/mm/early_ioremap.c | 271 +++++++++++++++++++++++++++++++++++++++++
arch/arm/mm/mmu.c | 4 +
7 files changed, 334 insertions(+), 2 deletions(-)
create mode 100644 arch/arm/mm/early_ioremap.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 43594d5..53a82da 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1805,6 +1805,13 @@ 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
+ depends on MMU
+ bool "Provide early_ioremap() support for kernel initialization."
+ help
+ Provides a mechanism for kernel initialisation code to temporarily
+ map, in a highmem-agnostic way, memory pages in before paging_init().
+
config SECCOMP
bool
prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index bbae919..a2a5f50 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -1,6 +1,8 @@
#ifndef _ASM_FIXMAP_H
#define _ASM_FIXMAP_H
+#include <linux/bug.h>
+
/*
* Nothing too fancy for now.
*
@@ -20,13 +22,38 @@
#define FIX_KMAP_BEGIN 0
#define FIX_KMAP_END (FIXADDR_SIZE >> PAGE_SHIFT)
+/*
+ * 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)
+#define FIX_BTMAP_BEGIN FIX_KMAP_BEGIN
+#define FIX_BTMAP_END (FIX_KMAP_END - 1)
+
+#define clear_fixmap(idx) \
+ __set_fixmap(idx, 0, __pgprot(0))
+
#define __fix_to_virt(x) (FIXADDR_START + ((x) << PAGE_SHIFT))
#define __virt_to_fix(x) (((x) - FIXADDR_START) >> PAGE_SHIFT)
extern void __this_fixmap_does_not_exist(void);
-static inline unsigned long fix_to_virt(const unsigned int idx)
+static __always_inline unsigned long fix_to_virt(const unsigned int idx)
{
+ /*
+ * this branch gets completely eliminated after inlining,
+ * except when someone tries to use fixaddr indices in an
+ * illegal way. (such as mixing up address types or using
+ * out-of-range indices).
+ *
+ * If it doesn't get removed, the linker will complain
+ * loudly with a reasonably clear error message..
+ */
if (idx >= FIX_KMAP_END)
__this_fixmap_does_not_exist();
return __fix_to_virt(idx);
@@ -38,4 +65,4 @@ static inline unsigned int virt_to_fix(const unsigned long vaddr)
return __virt_to_fix(vaddr);
}
-#endif
+#endif /* _ASM_FIXMAP_H */
diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index d070741..35499d9 100644
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -26,6 +26,7 @@
#include <linux/types.h>
#include <asm/byteorder.h>
#include <asm/memory.h>
+#include <asm/pgtable.h>
#include <asm-generic/pci_iomap.h>
/*
@@ -397,5 +398,21 @@ extern int devmem_is_allowed(unsigned long pfn);
extern void register_isa_ports(unsigned int mmio, unsigned int io,
unsigned int io_shift);
+/*
+ * early_ioremap() and early_iounmap() are for temporary early boot-time
+ * mappings, before the real ioremap() is functional.
+ * A boot-time mapping is currently limited to at most 16 pages.
+ *
+ * This is all squashed by paging_init().
+ */
+extern void early_ioremap_init(void);
+extern void early_ioremap_reset(void);
+extern void __iomem *early_remap(resource_size_t phys_addr,
+ unsigned long size, u32 prot);
+#define early_ioremap(x, y) early_remap(x, y, L_PTE_MT_DEV_NONSHARED)
+#define early_memremap(x, y) early_remap(x, y, L_PTE_MT_UNCACHED)
+
+extern void early_iounmap(void __iomem *addr, unsigned long size);
+
#endif /* __KERNEL__ */
#endif /* __ASM_ARM_IO_H */
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index afc2489..ce913ea 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -36,6 +36,7 @@
#include <asm/cpu.h>
#include <asm/cputype.h>
#include <asm/elf.h>
+#include <asm/io.h>
#include <asm/procinfo.h>
#include <asm/psci.h>
#include <asm/sections.h>
@@ -877,6 +878,10 @@ void __init setup_arch(char **cmdline_p)
parse_early_param();
+#ifdef CONFIG_EARLY_IOREMAP
+ early_ioremap_init();
+#endif
+
sort(&meminfo.bank, meminfo.nr_banks, sizeof(meminfo.bank[0]), meminfo_cmp, NULL);
sanity_check_meminfo();
arm_memblock_init(&meminfo, mdesc);
diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile
index ecfe6e5..fea855e 100644
--- a/arch/arm/mm/Makefile
+++ b/arch/arm/mm/Makefile
@@ -15,6 +15,7 @@ endif
obj-$(CONFIG_MODULES) += proc-syms.o
obj-$(CONFIG_ALIGNMENT_TRAP) += alignment.o
+obj-$(CONFIG_EARLY_IOREMAP) += early_ioremap.o
obj-$(CONFIG_HIGHMEM) += highmem.o
obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
diff --git a/arch/arm/mm/early_ioremap.c b/arch/arm/mm/early_ioremap.c
new file mode 100644
index 0000000..9bb1339
--- /dev/null
+++ b/arch/arm/mm/early_ioremap.c
@@ -0,0 +1,271 @@
+/*
+ * 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 int __initdata early_ioremap_debug;
+
+static int __init early_ioremap_debug_setup(char *str)
+{
+ early_ioremap_debug = 1;
+
+ return 0;
+}
+early_param("early_ioremap_debug", early_ioremap_debug_setup);
+
+static pte_t __initdata bm_pte[PTRS_PER_PTE] __aligned(PTRS_PER_PTE * sizeof(pte_t));
+static __initdata int after_paging_init;
+
+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)];
+}
+
+static unsigned long slot_virt[FIX_BTMAPS_SLOTS] __initdata;
+
+void __init early_ioremap_init(void)
+{
+ pmd_t *pmd;
+ int i;
+ u64 desc;
+
+ if (early_ioremap_debug)
+ pr_info("early_ioremap_init()\n");
+
+ for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
+ slot_virt[i] = __fix_to_virt(FIX_BTMAP_BEGIN + NR_FIX_BTMAPS*i);
+ if (early_ioremap_debug)
+ pr_info(" %lu byte slot @ 0x%08x\n",
+ NR_FIX_BTMAPS * PAGE_SIZE, (u32)slot_virt[i]);
+ }
+
+ pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
+ desc = *pmd;
+ memset(bm_pte, 0, sizeof(bm_pte));
+
+ pmd_populate_kernel(NULL, pmd, bm_pte);
+ desc = *pmd;
+
+ 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: %lu\n", FIX_BTMAP_END);
+ pr_warn("FIX_BTMAP_BEGIN: %d\n", FIX_BTMAP_BEGIN);
+ }
+}
+
+void __init early_ioremap_reset(void)
+{
+ after_paging_init = 1;
+}
+
+static void __init __early_set_fixmap(unsigned long 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, 0xfff00000, pte,
+ pfn_pte(phys >> PAGE_SHIFT, flags));
+ else
+ pte_clear(NULL, addr, pte);
+ flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+ desc = *pte;
+}
+
+static inline void __init early_set_fixmap(unsigned long idx,
+ phys_addr_t phys, pgprot_t prot)
+{
+ __early_set_fixmap(idx, phys, prot);
+}
+
+static inline void __init early_clear_fixmap(unsigned long idx)
+{
+ __early_set_fixmap(idx, 0, __pgprot(0));
+}
+
+static void __iomem *prev_map[FIX_BTMAPS_SLOTS] __initdata;
+static unsigned long prev_size[FIX_BTMAPS_SLOTS] __initdata;
+
+static void __init __iomem *
+__early_remap(resource_size_t phys_addr, unsigned long size, pgprot_t prot)
+{
+ unsigned long offset;
+ resource_size_t last_addr;
+ unsigned int nrpages;
+ unsigned long idx;
+ int i, slot;
+
+ slot = -1;
+ for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
+ if (!prev_map[i]) {
+ slot = i;
+ break;
+ }
+ }
+
+ if (slot < 0) {
+ pr_info("early_iomap(%08llx, %08lx) not found slot\n",
+ (u64)phys_addr, size);
+ WARN_ON(1);
+ return NULL;
+ }
+
+ if (early_ioremap_debug) {
+ pr_info("early_ioremap(%08llx, %08lx) [%d] => ",
+ (u64)phys_addr, size, slot);
+ }
+
+ /* Don't allow wraparound or zero size */
+ last_addr = phys_addr + size - 1;
+ if (!size || last_addr < phys_addr) {
+ WARN_ON(1);
+ return NULL;
+ }
+
+ prev_size[slot] = size;
+ /*
+ * Mappings have to be page-aligned
+ */
+ offset = phys_addr & ~PAGE_MASK;
+ phys_addr &= PAGE_MASK;
+ size = PAGE_ALIGN(last_addr + 1) - phys_addr;
+
+ /*
+ * Mappings have to fit in the FIX_BTMAP area.
+ */
+ nrpages = size >> PAGE_SHIFT;
+ if (nrpages > NR_FIX_BTMAPS) {
+ WARN_ON(1);
+ return NULL;
+ }
+
+ /*
+ * Ok, go for it..
+ */
+ idx = FIX_BTMAP_BEGIN + slot * NR_FIX_BTMAPS;
+ while (nrpages > 0) {
+ early_set_fixmap(idx, phys_addr, prot);
+ phys_addr += PAGE_SIZE;
+ idx++;
+ --nrpages;
+ }
+ if (early_ioremap_debug)
+ pr_cont("%08lx + %08lx\n", offset, slot_virt[slot]);
+
+ prev_map[slot] = (void __iomem *)(offset + slot_virt[slot]);
+ return prev_map[slot];
+}
+
+/* Remap an IO device */
+void __init __iomem *
+early_remap(resource_size_t phys_addr, unsigned long size, u32 prot)
+{
+ if (after_paging_init) {
+ WARN_ON(1);
+ return NULL;
+ }
+
+ /*
+ * PAGE_KERNEL depends on not-yet-initialised variables.
+ * We don't care about coherency or executability of early_ioremap
+ * pages anyway.
+ */
+ prot |= L_PTE_YOUNG | L_PTE_PRESENT;
+ return __early_remap(phys_addr, size, prot);
+}
+
+
+void __init early_iounmap(void __iomem *addr, unsigned long size)
+{
+ unsigned long virt_addr;
+ unsigned long offset;
+ unsigned int nrpages;
+ unsigned long idx;
+ int i, slot;
+
+ if (after_paging_init) {
+ WARN_ON(1);
+ return;
+ }
+
+ slot = -1;
+ for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
+ if (prev_map[i] == addr) {
+ slot = i;
+ break;
+ }
+ }
+
+ if (slot < 0) {
+ pr_info("early_iounmap(%p, %08lx) not found slot\n",
+ addr, size);
+ WARN_ON(1);
+ return;
+ }
+
+ if (prev_size[slot] != size) {
+ pr_info("early_iounmap(%p, %08lx) [%d] size not consistent %08lx\n",
+ addr, size, slot, prev_size[slot]);
+ WARN_ON(1);
+ return;
+ }
+
+ if (early_ioremap_debug)
+ pr_info("early_iounmap(%p, %08lx) [%d]\n", addr, size, slot);
+
+ virt_addr = (unsigned long)addr;
+ if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN)) {
+ WARN_ON(1);
+ return;
+ }
+ offset = virt_addr & ~PAGE_MASK;
+ nrpages = PAGE_ALIGN(offset + size) >> PAGE_SHIFT;
+
+ idx = FIX_BTMAP_BEGIN + slot * NR_FIX_BTMAPS;
+ while (nrpages > 0) {
+ early_clear_fixmap(idx);
+ idx++;
+ --nrpages;
+ }
+ prev_map[slot] = NULL;
+}
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 53cdbd3..f4adb41 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -28,6 +28,7 @@
#include <asm/highmem.h>
#include <asm/system_info.h>
#include <asm/traps.h>
+#include <asm/io.h>
#include <asm/mach/arch.h>
#include <asm/mach/map.h>
@@ -1340,4 +1341,7 @@ void __init paging_init(struct machine_desc *mdesc)
empty_zero_page = virt_to_page(zero_page);
__flush_dcache_page(NULL, empty_zero_page);
+#ifdef CONFIG_EARLY_IOREMAP
+ early_ioremap_reset();
+#endif
}
--
1.7.10.4
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