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Date: Tue, 29 Apr 2008 11:32:37 -0400
From: Rik van Riel <riel@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: akpm@...ux-foundation.org, ajackson@...hat.com, airlied@...hat.com,
benh@...nel.crashing.org
Subject: [PATCH 1/3] make access_process_vm work on device memory
Make access_process_vm work on VM_IO or VM_PFNMAP VMAs. This allows ptrace
and /proc/pid/mem access to work on eg. video card memory mapped by the X
server and lays the groundwork for gdb support for PPC Cell SPU memory.
Signed-off-by: Rik van Riel <riel@...hat.com>
Signed-off-by: Benjamin Herrensmidt <benh@...nel.crashing.org>
---
arch/x86/mm/ioremap.c | 8 ++
include/asm-x86/io_32.h | 3 +
include/asm-x86/io_64.h | 3 +
include/linux/mm.h | 6 ++
mm/memory.c | 134 +++++++++++++++++++++++++++++++++++++++++-------
5 files changed, 136 insertions(+), 18 deletions(-)
Index: linux-2.6.25-mm1/mm/memory.c
===================================================================
--- linux-2.6.25-mm1.orig/mm/memory.c 2008-04-27 11:06:04.000000000 -0400
+++ linux-2.6.25-mm1/mm/memory.c 2008-04-29 00:52:01.000000000 -0400
@@ -2720,6 +2720,86 @@ int in_gate_area_no_task(unsigned long a
#endif /* __HAVE_ARCH_GATE_AREA */
+#ifdef _HAVE_ARCH_IOREMAP_PROT
+static resource_size_t follow_phys(struct vm_area_struct *vma,
+ unsigned long address, unsigned int flags,
+ unsigned long *prot)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *ptep, pte;
+ spinlock_t *ptl;
+ resource_size_t phys_addr = 0;
+ struct mm_struct *mm = vma->vm_mm;
+
+ VM_BUG_ON(!(vma->vm_flags & (VM_IO | VM_PFNMAP)));
+
+ pgd = pgd_offset(mm, address);
+ if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
+ goto no_page_table;
+
+ pud = pud_offset(pgd, address);
+ if (pud_none(*pud) || unlikely(pud_bad(*pud)))
+ goto no_page_table;
+
+ pmd = pmd_offset(pud, address);
+ if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
+ goto no_page_table;
+
+ /* We cannot handle huge page PFN maps. Luckily they don't exist. */
+ if (pmd_huge(*pmd))
+ goto no_page_table;
+
+ ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
+ if (!ptep)
+ goto out;
+
+ pte = *ptep;
+ if (!pte_present(pte))
+ goto unlock;
+ if ((flags & FOLL_WRITE) && !pte_write(pte))
+ goto unlock;
+ phys_addr = pte_pfn(pte);
+ phys_addr <<= PAGE_SHIFT; /* Shift here to avoid overflow on PAE? */
+
+ *prot = pgprot_val(pte_pgprot(pte));
+
+unlock:
+ pte_unmap_unlock(ptep, ptl);
+out:
+ return phys_addr;
+no_page_table:
+ return 0;
+}
+
+int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
+ void *buf, int len, int write)
+{
+ resource_size_t phys_addr;
+ unsigned long prot = 0;
+ void *maddr;
+ int offset = addr & (PAGE_SIZE-1);
+
+ if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+ return -EINVAL;
+
+ phys_addr = follow_phys(vma, addr, write, &prot);
+
+ if (!phys_addr)
+ return -EINVAL;
+
+ maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
+ if (write)
+ memcpy_toio(maddr + offset, buf, len);
+ else
+ memcpy_fromio(buf, maddr + offset, len);
+ iounmap(maddr);
+
+ return len;
+}
+#endif
+
/*
* Access another process' address space.
* Source/target buffer must be kernel space,
@@ -2729,7 +2809,6 @@ int access_process_vm(struct task_struct
{
struct mm_struct *mm;
struct vm_area_struct *vma;
- struct page *page;
void *old_buf = buf;
mm = get_task_mm(tsk);
@@ -2741,28 +2820,47 @@ int access_process_vm(struct task_struct
while (len) {
int bytes, ret, offset;
void *maddr;
+ struct page *page = NULL;
ret = get_user_pages(tsk, mm, addr, 1,
write, 1, &page, &vma);
- if (ret <= 0)
- break;
-
- bytes = len;
- offset = addr & (PAGE_SIZE-1);
- if (bytes > PAGE_SIZE-offset)
- bytes = PAGE_SIZE-offset;
-
- maddr = kmap(page);
- if (write) {
- copy_to_user_page(vma, page, addr,
- maddr + offset, buf, bytes);
- set_page_dirty_lock(page);
+ if (ret <= 0) {
+ /*
+ * Check if this is a VM_IO | VM_PFNMAP VMA, which
+ * we can access using slightly different code.
+ */
+#ifdef _HAVE_ARCH_IOREMAP_PROT
+ vma = find_vma(mm, addr);
+ if (!vma)
+ break;
+ if (vma->vm_ops && vma->vm_ops->access)
+ ret = vma->vm_ops->access(vma, addr, buf,
+ len, write);
+ else
+ ret = generic_access_phys(vma, addr, buf,
+ len, write);
+ if (ret <= 0)
+#endif
+ break;
+ bytes = ret;
} else {
- copy_from_user_page(vma, page, addr,
- buf, maddr + offset, bytes);
+ bytes = len;
+ offset = addr & (PAGE_SIZE-1);
+ if (bytes > PAGE_SIZE-offset)
+ bytes = PAGE_SIZE-offset;
+
+ maddr = kmap(page);
+ if (write) {
+ copy_to_user_page(vma, page, addr,
+ maddr + offset, buf, bytes);
+ set_page_dirty_lock(page);
+ } else {
+ copy_from_user_page(vma, page, addr,
+ buf, maddr + offset, bytes);
+ }
+ kunmap(page);
+ page_cache_release(page);
}
- kunmap(page);
- page_cache_release(page);
len -= bytes;
buf += bytes;
addr += bytes;
Index: linux-2.6.25-mm1/arch/x86/mm/ioremap.c
===================================================================
--- linux-2.6.25-mm1.orig/arch/x86/mm/ioremap.c 2008-04-22 10:33:42.000000000 -0400
+++ linux-2.6.25-mm1/arch/x86/mm/ioremap.c 2008-04-28 22:06:08.000000000 -0400
@@ -287,6 +287,14 @@ void __iomem *ioremap_cache(resource_siz
}
EXPORT_SYMBOL(ioremap_cache);
+void __iomem *ioremap_prot(resource_size_t phys_addr, unsigned long size,
+ unsigned long prot_val)
+{
+ return __ioremap_caller(phys_addr, size, (prot_val & _PAGE_CACHE_MASK),
+ __builtin_return_address(0));
+}
+EXPORT_SYMBOL(ioremap_prot);
+
/**
* iounmap - Free a IO remapping
* @addr: virtual address from ioremap_*
Index: linux-2.6.25-mm1/include/asm-x86/io_32.h
===================================================================
--- linux-2.6.25-mm1.orig/include/asm-x86/io_32.h 2008-04-22 10:33:44.000000000 -0400
+++ linux-2.6.25-mm1/include/asm-x86/io_32.h 2008-04-28 21:38:03.000000000 -0400
@@ -110,6 +110,9 @@ static inline void *phys_to_virt(unsigne
*/
extern void __iomem *ioremap_nocache(resource_size_t offset, unsigned long size);
extern void __iomem *ioremap_cache(resource_size_t offset, unsigned long size);
+extern void __iomem *ioremap_prot(resource_size_t offset, unsigned long size,
+ unsigned long prot_val);
+#define _HAVE_ARCH_IOREMAP_PROT
/*
* The default ioremap() behavior is non-cached:
Index: linux-2.6.25-mm1/include/asm-x86/io_64.h
===================================================================
--- linux-2.6.25-mm1.orig/include/asm-x86/io_64.h 2008-04-22 10:33:44.000000000 -0400
+++ linux-2.6.25-mm1/include/asm-x86/io_64.h 2008-04-28 21:37:42.000000000 -0400
@@ -175,6 +175,9 @@ extern void early_iounmap(void *addr, un
*/
extern void __iomem *ioremap_nocache(resource_size_t offset, unsigned long size);
extern void __iomem *ioremap_cache(resource_size_t offset, unsigned long size);
+extern void __iomem *ioremap_prot(resource_size_t offset, unsigned long size,
+ unsigned long prot_val);
+#define _HAVE_ARCH_IOREMAP_PROT
/*
* The default ioremap() behavior is non-cached:
Index: linux-2.6.25-mm1/include/linux/mm.h
===================================================================
--- linux-2.6.25-mm1.orig/include/linux/mm.h 2008-04-27 11:06:04.000000000 -0400
+++ linux-2.6.25-mm1/include/linux/mm.h 2008-04-28 22:01:26.000000000 -0400
@@ -171,6 +171,12 @@ struct vm_operations_struct {
/* notification that a previously read-only page is about to become
* writable, if an error is returned it will cause a SIGBUS */
int (*page_mkwrite)(struct vm_area_struct *vma, struct page *page);
+
+ /* called by access_process_vm when get_user_pages() fails, typically
+ * for use by special VMAs that can switch between memory and hardware
+ */
+ int (*access)(struct vm_area_struct *vma, unsigned long addr,
+ void *buf, int len, int write);
#ifdef CONFIG_NUMA
/*
* set_policy() op must add a reference to any non-NULL @new mempolicy
--
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