This patch makes preempt emulation more strict in differentiating its
own dr0 hardware breakpoint from a singlestep in return from kprobes
pre-handler that will invoke the post-handler through int1 debug TS on
eflags. This avoids GPF when kprobes returns from pre-handler with the
dr7 loaded with preempt emulation.
Signed-off-by: Andrea Arcangeli <[EMAIL PROTECTED]>
--- kvm-userland/kernel/preempt.c 2008-05-06 19:33:40.000000000 +0200
+++ /home/andrea/kernel/qumranet/kvm/kernel/preempt.c 2008-06-05
00:18:06.000000000 +0200
@@ -140,6 +147,11 @@
"cmp $0x701, " TMP " \n\t"
"pop " TMP " \n\t"
"jnz .Lnotme \n\t"
+ "push " TMP " \n\t"
+ "mov %db6, " TMP " \n\t"
+ "test $0x1, " TMP " \n\t"
+ "pop " TMP " \n\t"
+ "jz .Lnotme \n\t"
SAVE_REGS "\n\t"
#ifdef CONFIG_X86_64
"leaq 120(%rsp),%rdi\n\t"
--
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