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authorZachary Amsden <zach@vmware.com>2007-02-13 07:26:21 -0500
committerAndi Kleen <andi@basil.nowhere.org>2007-02-13 07:26:21 -0500
commit7b3552024380f306a6c50d5105d18d9d4258fa4e (patch)
tree904a408768b216be7f759b4a190809f851a914d5 /include/asm-i386/segment.h
parentbbab4f3bb7f528d2b8ccb5de9ae5f6ff3fb29684 (diff)
[PATCH] i386: Profile pc badness
Profile_pc was broken when using paravirtualization because the assumption the kernel was running at CPL 0 was violated, causing bad logic to read a random value off the stack. The only way to be in kernel lock functions is to be in kernel code, so validate that assumption explicitly by checking the CS value. We don't want to be fooled by BIOS / APM segments and try to read those stacks, so only match KERNEL_CS. I moved some stuff in segment.h to make it prettier. Signed-off-by: Zachary Amsden <zach@vmware.com> Signed-off-by: Andi Kleen <ak@suse.de>
Diffstat (limited to 'include/asm-i386/segment.h')
-rw-r--r--include/asm-i386/segment.h19
1 files changed, 13 insertions, 6 deletions
diff --git a/include/asm-i386/segment.h b/include/asm-i386/segment.h
index 3c796af33776..065f10bfa487 100644
--- a/include/asm-i386/segment.h
+++ b/include/asm-i386/segment.h
@@ -83,14 +83,8 @@
83 * The GDT has 32 entries 83 * The GDT has 32 entries
84 */ 84 */
85#define GDT_ENTRIES 32 85#define GDT_ENTRIES 32
86
87#define GDT_SIZE (GDT_ENTRIES * 8) 86#define GDT_SIZE (GDT_ENTRIES * 8)
88 87
89/* Matches __KERNEL_CS and __USER_CS (they must be 2 entries apart) */
90#define SEGMENT_IS_FLAT_CODE(x) (((x) & 0xec) == GDT_ENTRY_KERNEL_CS * 8)
91/* Matches PNP_CS32 and PNP_CS16 (they must be consecutive) */
92#define SEGMENT_IS_PNP_CODE(x) (((x) & 0xf4) == GDT_ENTRY_PNPBIOS_BASE * 8)
93
94/* Simple and small GDT entries for booting only */ 88/* Simple and small GDT entries for booting only */
95 89
96#define GDT_ENTRY_BOOT_CS 2 90#define GDT_ENTRY_BOOT_CS 2
@@ -134,4 +128,17 @@
134#ifndef CONFIG_PARAVIRT 128#ifndef CONFIG_PARAVIRT
135#define get_kernel_rpl() 0 129#define get_kernel_rpl() 0
136#endif 130#endif
131/*
132 * Matching rules for certain types of segments.
133 */
134
135/* Matches only __KERNEL_CS, ignoring PnP / USER / APM segments */
136#define SEGMENT_IS_KERNEL_CODE(x) (((x) & 0xfc) == GDT_ENTRY_KERNEL_CS * 8)
137
138/* Matches __KERNEL_CS and __USER_CS (they must be 2 entries apart) */
139#define SEGMENT_IS_FLAT_CODE(x) (((x) & 0xec) == GDT_ENTRY_KERNEL_CS * 8)
140
141/* Matches PNP_CS32 and PNP_CS16 (they must be consecutive) */
142#define SEGMENT_IS_PNP_CODE(x) (((x) & 0xf4) == GDT_ENTRY_PNPBIOS_BASE * 8)
143
137#endif 144#endif