mm: create generic early_ioremap() support

This patch creates a generic implementation of early_ioremap() support
based on the existing x86 implementation.  early_ioremp() is useful for
early boot code which needs to temporarily map I/O or memory regions
before normal mapping functions such as ioremap() are available.

Some architectures have optional MMU.  In the no-MMU case, the remap
functions simply return the passed in physical address and the unmap
functions do nothing.

Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: Borislav Petkov <borislav.petkov@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/asm-generic/early_ioremap.h b/include/asm-generic/early_ioremap.h
new file mode 100644 (file)
index 0000000..a5de55c
--- /dev/null
+++ b/include/asm-generic/early_ioremap.h
@@ -0,0 +1,42 @@
+#ifndef _ASM_EARLY_IOREMAP_H_
+#define _ASM_EARLY_IOREMAP_H_
+
+#include <linux/types.h>
+
+/*
+ * early_ioremap() and early_iounmap() are for temporary early boot-time
+ * mappings, before the real ioremap() is functional.
+ */
+extern void __iomem *early_ioremap(resource_size_t phys_addr,
+                                  unsigned long size);
+extern void *early_memremap(resource_size_t phys_addr,
+                           unsigned long size);
+extern void early_iounmap(void __iomem *addr, unsigned long size);
+extern void early_memunmap(void *addr, unsigned long size);
+
+/*
+ * Weak function called by early_ioremap_reset(). It does nothing, but
+ * architectures may provide their own version to do any needed cleanups.
+ */
+extern void early_ioremap_shutdown(void);
+
+#if defined(CONFIG_GENERIC_EARLY_IOREMAP) && defined(CONFIG_MMU)
+/* Arch-specific initialization */
+extern void early_ioremap_init(void);
+
+/* Generic initialization called by architecture code */
+extern void early_ioremap_setup(void);
+
+/*
+ * Called as last step in paging_init() so library can act
+ * accordingly for subsequent map/unmap requests.
+ */
+extern void early_ioremap_reset(void);
+
+#else
+static inline void early_ioremap_init(void) { }
+static inline void early_ioremap_setup(void) { }
+static inline void early_ioremap_reset(void) { }
+#endif
+
+#endif /* _ASM_EARLY_IOREMAP_H_ */

diff --git a/mm/Kconfig b/mm/Kconfig
index 37fbe1ef5239714dc8483783334a87b386ef985c..ebe5880c29d6cbe2306054f19bda87ffb3daa59a 100644 (file)
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -578,3 +578,6 @@ config PGTABLE_MAPPING
 
          You can check speed with zsmalloc benchmark:
          https://github.com/spartacus06/zsmapbench
+
+config GENERIC_EARLY_IOREMAP
+       bool

diff --git a/mm/Makefile b/mm/Makefile
index 23a6f7e23019468c7e6313405480a84026f651e9..9e5aaf92197d3fcc7038e86d9769dc0def5bf1c3 100644 (file)
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -61,3 +61,4 @@ obj-$(CONFIG_CLEANCACHE) += cleancache.o
 obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o
 obj-$(CONFIG_ZBUD)     += zbud.o
 obj-$(CONFIG_ZSMALLOC) += zsmalloc.o
+obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o

diff --git a/mm/early_ioremap.c b/mm/early_ioremap.c
new file mode 100644 (file)
index 0000000..e10ccd2
--- /dev/null
+++ b/mm/early_ioremap.c
@@ -0,0 +1,245 @@
+/*
+ * Provide common bits of early_ioremap() support for architectures needing
+ * temporary mappings during boot before ioremap() is available.
+ *
+ * This is mostly a direct copy of the x86 early_ioremap implementation.
+ *
+ * (C) Copyright 1995 1996, 2014 Linus Torvalds
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <asm/fixmap.h>
+
+#ifdef CONFIG_MMU
+static int early_ioremap_debug __initdata;
+
+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 int after_paging_init __initdata;
+
+void __init __weak early_ioremap_shutdown(void)
+{
+}
+
+void __init early_ioremap_reset(void)
+{
+       early_ioremap_shutdown();
+       after_paging_init = 1;
+}
+
+/*
+ * Generally, ioremap() is available after paging_init() has been called.
+ * Architectures wanting to allow early_ioremap after paging_init() can
+ * define __late_set_fixmap and __late_clear_fixmap to do the right thing.
+ */
+#ifndef __late_set_fixmap
+static inline void __init __late_set_fixmap(enum fixed_addresses idx,
+                                           phys_addr_t phys, pgprot_t prot)
+{
+       BUG();
+}
+#endif
+
+#ifndef __late_clear_fixmap
+static inline void __init __late_clear_fixmap(enum fixed_addresses idx)
+{
+       BUG();
+}
+#endif
+
+static void __iomem *prev_map[FIX_BTMAPS_SLOTS] __initdata;
+static unsigned long prev_size[FIX_BTMAPS_SLOTS] __initdata;
+static unsigned long slot_virt[FIX_BTMAPS_SLOTS] __initdata;
+
+void __init early_ioremap_setup(void)
+{
+       int i;
+
+       for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
+               if (WARN_ON(prev_map[i]))
+                       break;
+
+       for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
+               slot_virt[i] = __fix_to_virt(FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*i);
+}
+
+static int __init check_early_ioremap_leak(void)
+{
+       int count = 0;
+       int i;
+
+       for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
+               if (prev_map[i])
+                       count++;
+
+       if (WARN(count, KERN_WARNING
+                "Debug warning: early ioremap leak of %d areas detected.\n"
+                "please boot with early_ioremap_debug and report the dmesg.\n",
+                count))
+               return 1;
+       return 0;
+}
+late_initcall(check_early_ioremap_leak);
+
+static void __init __iomem *
+__early_ioremap(resource_size_t phys_addr, unsigned long size, pgprot_t prot)
+{
+       unsigned long offset;
+       resource_size_t last_addr;
+       unsigned int nrpages;
+       enum fixed_addresses idx;
+       int i, slot;
+
+       WARN_ON(system_state != SYSTEM_BOOTING);
+
+       slot = -1;
+       for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
+               if (!prev_map[i]) {
+                       slot = i;
+                       break;
+               }
+       }
+
+       if (WARN(slot < 0, "%s(%08llx, %08lx) not found slot\n",
+                __func__, (u64)phys_addr, size))
+               return NULL;
+
+       /* Don't allow wraparound or zero size */
+       last_addr = phys_addr + size - 1;
+       if (WARN_ON(!size || last_addr < phys_addr))
+               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 (WARN_ON(nrpages > NR_FIX_BTMAPS))
+               return NULL;
+
+       /*
+        * Ok, go for it..
+        */
+       idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*slot;
+       while (nrpages > 0) {
+               if (after_paging_init)
+                       __late_set_fixmap(idx, phys_addr, prot);
+               else
+                       __early_set_fixmap(idx, phys_addr, prot);
+               phys_addr += PAGE_SIZE;
+               --idx;
+               --nrpages;
+       }
+       WARN(early_ioremap_debug, "%s(%08llx, %08lx) [%d] => %08lx + %08lx\n",
+            __func__, (u64)phys_addr, size, slot, offset, slot_virt[slot]);
+
+       prev_map[slot] = (void __iomem *)(offset + slot_virt[slot]);
+       return prev_map[slot];
+}
+
+void __init early_iounmap(void __iomem *addr, unsigned long size)
+{
+       unsigned long virt_addr;
+       unsigned long offset;
+       unsigned int nrpages;
+       enum fixed_addresses idx;
+       int i, slot;
+
+       slot = -1;
+       for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
+               if (prev_map[i] == addr) {
+                       slot = i;
+                       break;
+               }
+       }
+
+       if (WARN(slot < 0, "early_iounmap(%p, %08lx) not found slot\n",
+                addr, size))
+               return;
+
+       if (WARN(prev_size[slot] != size,
+                "early_iounmap(%p, %08lx) [%d] size not consistent %08lx\n",
+                addr, size, slot, prev_size[slot]))
+               return;
+
+       WARN(early_ioremap_debug, "early_iounmap(%p, %08lx) [%d]\n",
+            addr, size, slot);
+
+       virt_addr = (unsigned long)addr;
+       if (WARN_ON(virt_addr < fix_to_virt(FIX_BTMAP_BEGIN)))
+               return;
+
+       offset = virt_addr & ~PAGE_MASK;
+       nrpages = PAGE_ALIGN(offset + size) >> PAGE_SHIFT;
+
+       idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*slot;
+       while (nrpages > 0) {
+               if (after_paging_init)
+                       __late_clear_fixmap(idx);
+               else
+                       __early_set_fixmap(idx, 0, FIXMAP_PAGE_CLEAR);
+               --idx;
+               --nrpages;
+       }
+       prev_map[slot] = NULL;
+}
+
+/* Remap an IO device */
+void __init __iomem *
+early_ioremap(resource_size_t phys_addr, unsigned long size)
+{
+       return __early_ioremap(phys_addr, size, FIXMAP_PAGE_IO);
+}
+
+/* Remap memory */
+void __init *
+early_memremap(resource_size_t phys_addr, unsigned long size)
+{
+       return (__force void *)__early_ioremap(phys_addr, size,
+                                              FIXMAP_PAGE_NORMAL);
+}
+#else /* CONFIG_MMU */
+
+void __init __iomem *
+early_ioremap(resource_size_t phys_addr, unsigned long size)
+{
+       return (__force void __iomem *)phys_addr;
+}
+
+/* Remap memory */
+void __init *
+early_memremap(resource_size_t phys_addr, unsigned long size)
+{
+       return (void *)phys_addr;
+}
+
+void __init early_iounmap(void __iomem *addr, unsigned long size)
+{
+}
+
+#endif /* CONFIG_MMU */
+
+
+void __init early_memunmap(void *addr, unsigned long size)
+{
+       early_iounmap((__force void __iomem *)addr, size);
+}