Re: [RFC 1/3] mmiotrace full patch, preview 3

From: Pekka Paalanen
Date: Mon Apr 28 2008 - 14:59:41 EST


On Mon, 28 Apr 2008 21:45:04 +0300
Pekka Paalanen <pq@xxxxxx> wrote:

> Hi all,
>
> this is the third full mmiotrace patch set for review (a bit late, sorry).
> These patches do not apply to any git tree that I know of, but after Ingo
> pushes a new version of his sched-devel/latest tree, these patches should
> be subtractable from there.
...
> This first patch adds the bulk of the new code, only introducing new files.
> The second patch establishes the interfaces to the ftrace framework, and
> the third patch hooks everything up into the Kbuild system, page fault
> handler, and ioremap functions.

arch/x86/Kconfig.debug | 28 ++++++++++++++++++++++++++++
arch/x86/mm/Makefile | 5 +++++
arch/x86/mm/fault.c | 13 +++++++++++++
arch/x86/mm/ioremap.c | 9 ++++++++-
arch/x86/mm/pageattr.c | 1 +
5 files changed, 55 insertions(+), 1 deletions(-)

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 1f237d2..fb0794e 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -170,6 +170,34 @@ config IOMMU_LEAK
Add a simple leak tracer to the IOMMU code. This is useful when you
are debugging a buggy device driver that leaks IOMMU mappings.

+config MMIOTRACE_HOOKS
+ bool
+
+config MMIOTRACE
+ bool "Memory mapped IO tracing"
+ depends on DEBUG_KERNEL && PCI
+ select TRACING
+ select MMIOTRACE_HOOKS
+ default y
+ help
+ Mmiotrace traces Memory Mapped I/O access and is meant for
+ debugging and reverse engineering. It is called from the ioremap
+ implementation and works via page faults. Tracing is disabled by
+ default and can be enabled at run-time.
+
+ See Documentation/tracers/mmiotrace.txt.
+ If you are not helping to develop drivers, say N.
+
+config MMIOTRACE_TEST
+ tristate "Test module for mmiotrace"
+ depends on MMIOTRACE && m
+ help
+ This is a dumb module for testing mmiotrace. It is very dangerous
+ as it will write garbage to IO memory starting at a given address.
+ However, it should be safe to use on e.g. unused portion of VRAM.
+
+ Say N, unless you absolutely know what you are doing.
+
#
# IO delay types:
#
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index b7b3e4c..07dab50 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -8,6 +8,11 @@ obj-$(CONFIG_X86_PTDUMP) += dump_pagetables.o

obj-$(CONFIG_HIGHMEM) += highmem_32.o

+obj-$(CONFIG_MMIOTRACE_HOOKS) += kmmio.o
+obj-$(CONFIG_MMIOTRACE) += mmiotrace.o
+mmiotrace-y := pf_in.o mmio-mod.o
+obj-$(CONFIG_MMIOTRACE_TEST) += testmmiotrace.o
+
ifeq ($(CONFIG_X86_32),y)
obj-$(CONFIG_NUMA) += discontig_32.o
else
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 4145597..0440dce 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -26,6 +26,7 @@
#include <linux/uaccess.h>
#include <linux/kdebug.h>
#include <linux/magic.h>
+#include <linux/mmiotrace.h>

#include <asm/system.h>
#include <asm/desc.h>
@@ -51,6 +52,16 @@
#define PF_RSVD (1<<3)
#define PF_INSTR (1<<4)

+static inline int kmmio_fault(struct pt_regs *regs, unsigned long addr)
+{
+#ifdef CONFIG_MMIOTRACE_HOOKS
+ if (unlikely(is_kmmio_active()))
+ if (kmmio_handler(regs, addr) == 1)
+ return -1;
+#endif
+ return 0;
+}
+
static inline int notify_page_fault(struct pt_regs *regs)
{
#ifdef CONFIG_KPROBES
@@ -623,6 +634,8 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)

if (notify_page_fault(regs))
return;
+ if (unlikely(kmmio_fault(regs, address)))
+ return;

/*
* We fault-in kernel-space virtual memory on-demand. The
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index d176b23..68b287d 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -12,6 +12,7 @@
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
+#include <linux/mmiotrace.h>

#include <asm/cacheflush.h>
#include <asm/e820.h>
@@ -126,6 +127,7 @@ static void __iomem *__ioremap(resource_size_t phys_addr, unsigned long size,
unsigned long new_prot_val;
pgprot_t prot;
int retval;
+ void __iomem *ret_addr;

/* Don't allow wraparound or zero size */
last_addr = phys_addr + size - 1;
@@ -229,7 +231,10 @@ static void __iomem *__ioremap(resource_size_t phys_addr, unsigned long size,
return NULL;
}

- return (void __iomem *) (vaddr + offset);
+ ret_addr = (void __iomem *) (vaddr + offset);
+ mmiotrace_ioremap(phys_addr, size, ret_addr);
+
+ return ret_addr;
}

/**
@@ -306,6 +311,8 @@ void iounmap(volatile void __iomem *addr)
addr < phys_to_virt(ISA_END_ADDRESS))
return;

+ mmiotrace_iounmap(addr);
+
addr = (volatile void __iomem *)
(PAGE_MASK & (unsigned long __force)addr);

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index bd5e05c..099374b 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -227,6 +227,7 @@ pte_t *lookup_address(unsigned long address, unsigned int *level)

return pte_offset_kernel(pmd, address);
}
+EXPORT_SYMBOL_GPL(lookup_address);

/*
* Set the new pmd in all the pgds we know about:
--
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