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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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a25b931684
The KVM code has some repeated bugs in it around use of __pa() on per-cpu data. Those data are not in an area on which using __pa() is valid. However, they are also called early enough in boot that __vmalloc_start_set is not set, and thus the CONFIG_DEBUG_VIRTUAL debugging does not catch them. This adds a check to also verify __pa() calls against max_low_pfn, which we can use earler in boot than is_vmalloc_addr(). However, if we are super-early in boot, max_low_pfn=0 and this will trip on every call, so also make sure that max_low_pfn is set before we try to use it. With this patch applied, CONFIG_DEBUG_VIRTUAL will actually catch the bug I was chasing (and fix later in this series). I'd love to find a generic way so that any __pa() call on percpu areas could do a BUG_ON(), but there don't appear to be any nice and easy ways to check if an address is a percpu one. Anybody have ideas on a way to do this? Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/20130122212430.F46F8159@kernel.stglabs.ibm.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
99 lines
2.2 KiB
C
99 lines
2.2 KiB
C
#include <linux/bootmem.h>
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#include <linux/mmdebug.h>
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#include <linux/module.h>
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#include <linux/mm.h>
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#include <asm/page.h>
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#include "physaddr.h"
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#ifdef CONFIG_X86_64
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#ifdef CONFIG_DEBUG_VIRTUAL
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unsigned long __phys_addr(unsigned long x)
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{
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unsigned long y = x - __START_KERNEL_map;
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/* use the carry flag to determine if x was < __START_KERNEL_map */
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if (unlikely(x > y)) {
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x = y + phys_base;
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VIRTUAL_BUG_ON(y >= KERNEL_IMAGE_SIZE);
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} else {
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x = y + (__START_KERNEL_map - PAGE_OFFSET);
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/* carry flag will be set if starting x was >= PAGE_OFFSET */
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VIRTUAL_BUG_ON((x > y) || !phys_addr_valid(x));
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}
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return x;
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}
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EXPORT_SYMBOL(__phys_addr);
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unsigned long __phys_addr_symbol(unsigned long x)
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{
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unsigned long y = x - __START_KERNEL_map;
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/* only check upper bounds since lower bounds will trigger carry */
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VIRTUAL_BUG_ON(y >= KERNEL_IMAGE_SIZE);
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return y + phys_base;
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}
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EXPORT_SYMBOL(__phys_addr_symbol);
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#endif
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bool __virt_addr_valid(unsigned long x)
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{
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unsigned long y = x - __START_KERNEL_map;
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/* use the carry flag to determine if x was < __START_KERNEL_map */
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if (unlikely(x > y)) {
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x = y + phys_base;
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if (y >= KERNEL_IMAGE_SIZE)
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return false;
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} else {
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x = y + (__START_KERNEL_map - PAGE_OFFSET);
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/* carry flag will be set if starting x was >= PAGE_OFFSET */
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if ((x > y) || !phys_addr_valid(x))
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return false;
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}
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return pfn_valid(x >> PAGE_SHIFT);
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}
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EXPORT_SYMBOL(__virt_addr_valid);
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#else
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#ifdef CONFIG_DEBUG_VIRTUAL
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unsigned long __phys_addr(unsigned long x)
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{
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unsigned long phys_addr = x - PAGE_OFFSET;
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/* VMALLOC_* aren't constants */
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VIRTUAL_BUG_ON(x < PAGE_OFFSET);
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VIRTUAL_BUG_ON(__vmalloc_start_set && is_vmalloc_addr((void *) x));
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/* max_low_pfn is set early, but not _that_ early */
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if (max_low_pfn) {
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VIRTUAL_BUG_ON((phys_addr >> PAGE_SHIFT) > max_low_pfn);
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BUG_ON(slow_virt_to_phys((void *)x) != phys_addr);
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}
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return phys_addr;
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}
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EXPORT_SYMBOL(__phys_addr);
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#endif
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bool __virt_addr_valid(unsigned long x)
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{
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if (x < PAGE_OFFSET)
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return false;
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if (__vmalloc_start_set && is_vmalloc_addr((void *) x))
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return false;
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if (x >= FIXADDR_START)
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return false;
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return pfn_valid((x - PAGE_OFFSET) >> PAGE_SHIFT);
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}
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EXPORT_SYMBOL(__virt_addr_valid);
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#endif /* CONFIG_X86_64 */
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