From d53d9bc0cf783e93b374de3895145c7375e570ba Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 2 Sep 2020 15:26:02 +0200 Subject: x86/debug: Change thread.debugreg6 to thread.virtual_dr6 Current usage of thread.debugreg6 is convoluted at best. It starts life as a copy of the hardware DR6 value, but then various bits are cleared and set. Replace this with a new variable thread.virtual_dr6 that is initialized to 0 when DR6 is read and only gains bits, at the same time the actual (on stack) dr6 value which is read from the hardware only gets bits cleared. Suggested-by: Andy Lutomirski Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Tested-by: Daniel Thompson Link: https://lore.kernel.org/r/20200902133201.415372940@infradead.org --- arch/x86/kernel/ptrace.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/x86/kernel/ptrace.c') diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 5f982896dc0b..bedca011459c 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -465,7 +465,7 @@ static void ptrace_triggered(struct perf_event *bp, break; } - thread->debugreg6 |= (DR_TRAP0 << i); + thread->virtual_dr6 |= (DR_TRAP0 << i); } /* @@ -601,7 +601,7 @@ static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n) if (bp) val = bp->hw.info.address; } else if (n == 6) { - val = thread->debugreg6 ^ DR6_RESERVED; /* Flip back to arch polarity */ + val = thread->virtual_dr6 ^ DR6_RESERVED; /* Flip back to arch polarity */ } else if (n == 7) { val = thread->ptrace_dr7; } @@ -657,7 +657,7 @@ static int ptrace_set_debugreg(struct task_struct *tsk, int n, if (n < HBP_NUM) { rc = ptrace_set_breakpoint_addr(tsk, n, val); } else if (n == 6) { - thread->debugreg6 = val ^ DR6_RESERVED; /* Flip to positive polarity */ + thread->virtual_dr6 = val ^ DR6_RESERVED; /* Flip to positive polarity */ rc = 0; } else if (n == 7) { rc = ptrace_write_dr7(tsk, val); -- cgit v1.2.3