3c2e2e6816
When the kernel is running in secure boot mode, we lock down the kernel to prevent userspace from modifying the running kernel image. Whilst this includes prohibiting access to things like /dev/mem, it must also prevent access by means of configuring driver modules in such a way as to cause a device to access or modify the kernel image. To this end, annotate module_param* statements that refer to hardware configuration and indicate for future reference what type of parameter they specify. The parameter parser in the core sees this information and can skip such parameters with an error message if the kernel is locked down. The module initialisation then runs as normal, but just sees whatever the default values for those parameters is. Note that we do still need to do the module initialisation because some drivers have viable defaults set in case parameters aren't specified and some drivers support automatic configuration (e.g. PNP or PCI) in addition to manually coded parameters. This patch annotates drivers in arch/x86/mm/. [Note: With respect to testmmiotrace, an additional patch will be added separately that makes the module refuse to load if the kernel is locked down.] Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> cc: Ingo Molnar <mingo@kernel.org> cc: Thomas Gleixner <tglx@linutronix.de> cc: "H. Peter Anvin" <hpa@zytor.com> cc: x86@kernel.org cc: linux-kernel@vger.kernel.org cc: nouveau@lists.freedesktop.org
141 lines
3.1 KiB
C
141 lines
3.1 KiB
C
/*
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* Written by Pekka Paalanen, 2008-2009 <pq@iki.fi>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/io.h>
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#include <linux/mmiotrace.h>
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static unsigned long mmio_address;
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module_param_hw(mmio_address, ulong, iomem, 0);
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MODULE_PARM_DESC(mmio_address, " Start address of the mapping of 16 kB "
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"(or 8 MB if read_far is non-zero).");
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static unsigned long read_far = 0x400100;
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module_param(read_far, ulong, 0);
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MODULE_PARM_DESC(read_far, " Offset of a 32-bit read within 8 MB "
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"(default: 0x400100).");
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static unsigned v16(unsigned i)
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{
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return i * 12 + 7;
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}
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static unsigned v32(unsigned i)
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{
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return i * 212371 + 13;
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}
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static void do_write_test(void __iomem *p)
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{
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unsigned int i;
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pr_info("write test.\n");
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mmiotrace_printk("Write test.\n");
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for (i = 0; i < 256; i++)
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iowrite8(i, p + i);
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for (i = 1024; i < (5 * 1024); i += 2)
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iowrite16(v16(i), p + i);
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for (i = (5 * 1024); i < (16 * 1024); i += 4)
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iowrite32(v32(i), p + i);
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}
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static void do_read_test(void __iomem *p)
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{
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unsigned int i;
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unsigned errs[3] = { 0 };
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pr_info("read test.\n");
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mmiotrace_printk("Read test.\n");
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for (i = 0; i < 256; i++)
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if (ioread8(p + i) != i)
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++errs[0];
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for (i = 1024; i < (5 * 1024); i += 2)
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if (ioread16(p + i) != v16(i))
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++errs[1];
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for (i = (5 * 1024); i < (16 * 1024); i += 4)
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if (ioread32(p + i) != v32(i))
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++errs[2];
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mmiotrace_printk("Read errors: 8-bit %d, 16-bit %d, 32-bit %d.\n",
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errs[0], errs[1], errs[2]);
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}
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static void do_read_far_test(void __iomem *p)
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{
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pr_info("read far test.\n");
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mmiotrace_printk("Read far test.\n");
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ioread32(p + read_far);
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}
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static void do_test(unsigned long size)
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{
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void __iomem *p = ioremap_nocache(mmio_address, size);
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if (!p) {
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pr_err("could not ioremap, aborting.\n");
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return;
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}
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mmiotrace_printk("ioremap returned %p.\n", p);
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do_write_test(p);
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do_read_test(p);
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if (read_far && read_far < size - 4)
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do_read_far_test(p);
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iounmap(p);
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}
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/*
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* Tests how mmiotrace behaves in face of multiple ioremap / iounmaps in
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* a short time. We had a bug in deferred freeing procedure which tried
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* to free this region multiple times (ioremap can reuse the same address
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* for many mappings).
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*/
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static void do_test_bulk_ioremapping(void)
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{
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void __iomem *p;
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int i;
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for (i = 0; i < 10; ++i) {
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p = ioremap_nocache(mmio_address, PAGE_SIZE);
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if (p)
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iounmap(p);
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}
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/* Force freeing. If it will crash we will know why. */
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synchronize_rcu();
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}
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static int __init init(void)
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{
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unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
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if (mmio_address == 0) {
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pr_err("you have to use the module argument mmio_address.\n");
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pr_err("DO NOT LOAD THIS MODULE UNLESS YOU REALLY KNOW WHAT YOU ARE DOING!\n");
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return -ENXIO;
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}
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pr_warning("WARNING: mapping %lu kB @ 0x%08lx in PCI address space, "
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"and writing 16 kB of rubbish in there.\n",
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size >> 10, mmio_address);
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do_test(size);
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do_test_bulk_ioremapping();
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pr_info("All done.\n");
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return 0;
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}
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static void __exit cleanup(void)
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{
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pr_debug("unloaded.\n");
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}
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module_init(init);
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module_exit(cleanup);
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MODULE_LICENSE("GPL");
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