From 5bef80a4b826b9cee1c6aec7ecc371ec395260cc Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Thu, 26 Aug 2010 13:57:58 -0400 Subject: [PATCH] x86, iommu: Add proper dependency sort routine (and sanity check). We are using a very simple sort routine which sorts the .iommu_table array in the order of dependencies. Specifically each structure of iommu_table_entry has a field 'depend' which contains the function pointer to the IOMMU that MUST be run before us. We sort the array of structures so that the struct iommu_table_entry with no 'depend' field are first, and then the subsequent ones are the ones for which the 'depend' function has been already invoked (in other words, precede us). Using the kernel's version 'sort', which is a mergeheap is feasible, but would require making the comparison operator scan recursivly the array to satisfy the "heapify" process: setting the levels properly. The end result would much more complex than it should be an it is just much simpler to utilize this simple sort routine. Signed-off-by: Konrad Rzeszutek Wilk LKML-Reference: <1282845485-8991-4-git-send-email-konrad.wilk@oracle.com> CC: H. Peter Anvin CC: Fujita Tomonori Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/iommu_table.h | 6 ++ arch/x86/kernel/Makefile | 1 + arch/x86/kernel/pci-iommu_table.c | 89 ++++++++++++++++++++++++++++++ 3 files changed, 96 insertions(+) create mode 100644 arch/x86/kernel/pci-iommu_table.c diff --git a/arch/x86/include/asm/iommu_table.h b/arch/x86/include/asm/iommu_table.h index 435176f96a56..2124e3ef6f98 100644 --- a/arch/x86/include/asm/iommu_table.h +++ b/arch/x86/include/asm/iommu_table.h @@ -92,4 +92,10 @@ struct iommu_table_entry { #define IOMMU_INIT(_detect, _depend, _init, _late_init) \ __IOMMU_INIT(_detect, _depend, _init, _late_init, 0) +void sort_iommu_table(struct iommu_table_entry *start, + struct iommu_table_entry *finish); + +void check_iommu_entries(struct iommu_table_entry *start, + struct iommu_table_entry *finish); + #endif /* _ASM_X86_IOMMU_TABLE_H */ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 0925676266bd..6817546595ef 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -42,6 +42,7 @@ obj-y += bootflag.o e820.o obj-y += pci-dma.o quirks.o i8237.o topology.o kdebugfs.o obj-y += alternative.o i8253.o pci-nommu.o hw_breakpoint.o obj-y += tsc.o io_delay.o rtc.o +obj-y += pci-iommu_table.o obj-$(CONFIG_X86_TRAMPOLINE) += trampoline.o obj-y += process.o diff --git a/arch/x86/kernel/pci-iommu_table.c b/arch/x86/kernel/pci-iommu_table.c new file mode 100644 index 000000000000..55d745ec1181 --- /dev/null +++ b/arch/x86/kernel/pci-iommu_table.c @@ -0,0 +1,89 @@ +#include +#include +#include +#include + + +#define DEBUG 1 + +static struct iommu_table_entry * __init +find_dependents_of(struct iommu_table_entry *start, + struct iommu_table_entry *finish, + struct iommu_table_entry *q) +{ + struct iommu_table_entry *p; + + if (!q) + return NULL; + + for (p = start; p < finish; p++) + if (p->detect == q->depend) + return p; + + return NULL; +} + + +void __init sort_iommu_table(struct iommu_table_entry *start, + struct iommu_table_entry *finish) { + + struct iommu_table_entry *p, *q, tmp; + + for (p = start; p < finish; p++) { +again: + q = find_dependents_of(start, finish, p); + /* We are bit sneaky here. We use the memory address to figure + * out if the node we depend on is past our point, if so, swap. + */ + if (q > p) { + tmp = *p; + memmove(p, q, sizeof(*p)); + *q = tmp; + goto again; + } + } + +} + +#ifdef DEBUG +void __init check_iommu_entries(struct iommu_table_entry *start, + struct iommu_table_entry *finish) +{ + struct iommu_table_entry *p, *q, *x; + char sym_p[KSYM_SYMBOL_LEN]; + char sym_q[KSYM_SYMBOL_LEN]; + + /* Simple cyclic dependency checker. */ + for (p = start; p < finish; p++) { + q = find_dependents_of(start, finish, p); + x = find_dependents_of(start, finish, q); + if (p == x) { + sprint_symbol(sym_p, (unsigned long)p->detect); + sprint_symbol(sym_q, (unsigned long)q->detect); + + printk(KERN_ERR "CYCLIC DEPENDENCY FOUND! %s depends" \ + " on %s and vice-versa. BREAKING IT.\n", + sym_p, sym_q); + /* Heavy handed way..*/ + x->depend = 0; + } + } + + for (p = start; p < finish; p++) { + q = find_dependents_of(p, finish, p); + if (q && q > p) { + sprint_symbol(sym_p, (unsigned long)p->detect); + sprint_symbol(sym_q, (unsigned long)q->detect); + + printk(KERN_ERR "EXECUTION ORDER INVALID! %s "\ + "should be called before %s!\n", + sym_p, sym_q); + } + } +} +#else +inline void check_iommu_entries(struct iommu_table_entry *start, + struct iommu_table_entry *finish) +{ +} +#endif -- 2.39.2