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authorZachary Amsden <zach@vmware.com>2006-01-06 00:11:50 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-06 08:33:34 -0800
commitff6e8c0d5e47f0ceeebde86ec2f5919dbd5beb67 (patch)
treef7e50b5962b7b38ca025c0bf9ee48b618424cc6b /include/asm-i386/system.h
parenteb05c3249a8e8a675e79d221f4a0874dc10ec903 (diff)
[PATCH] x86: Cr4 is valid on some 486s
So some 486 processors do have CR4 register. Allow them to present it in register dumps by using the old fault technique rather than testing processor family. Thanks to Maciej for noticing this. Signed-off-by: Zachary Amsden <zach@vmware.com> Cc: "Seth, Rohit" <rohit.seth@intel.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/asm-i386/system.h')
-rw-r--r--include/asm-i386/system.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h
index 772f85da120..88b4d5c6f37 100644
--- a/include/asm-i386/system.h
+++ b/include/asm-i386/system.h
@@ -140,6 +140,19 @@ static inline unsigned long _get_base(char * addr)
:"=r" (__dummy)); \
__dummy; \
})
+
+#define read_cr4_safe() ({ \
+ unsigned int __dummy; \
+ /* This could fault if %cr4 does not exist */ \
+ __asm__("1: movl %%cr4, %0 \n" \
+ "2: \n" \
+ ".section __ex_table,\"a\" \n" \
+ ".long 1b,2b \n" \
+ ".previous \n" \
+ : "=r" (__dummy): "0" (0)); \
+ __dummy; \
+})
+
#define write_cr4(x) \
__asm__ __volatile__("movl %0,%%cr4": :"r" (x));
#define stts() write_cr0(8 | read_cr0())