arm64: ptrace: avoid using HW_BREAKPOINT_EMPTY for disabled events
Commit 8f34a1da35
("arm64: ptrace: use HW_BREAKPOINT_EMPTY type for
disabled breakpoints") fixed an issue with GDB trying to zero breakpoint
control registers. The problem there is that the arch hw_breakpoint code
will attempt to create a (disabled), execute breakpoint of length 0.
This will fail validation and report unexpected failure to GDB. To avoid
this, we treated disabled breakpoints as HW_BREAKPOINT_EMPTY, but that
seems to have broken with recent kernels, causing watchpoints to be
treated as TYPE_INST in the core code and returning ENOSPC for any
further breakpoints.
This patch fixes the problem by prioritising the `enable' field of the
breakpoint: if it is cleared, we simply update the perf_event_attr to
indicate that the thing is disabled and don't bother changing either the
type or the length. This reinforces the behaviour that the breakpoint
control register is essentially read-only apart from the enable bit
when disabling a breakpoint.
Cc: <stable@vger.kernel.org>
Reported-by: Aaron Liu <liucy214@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
parent
319e2e3f63
commit
cdc27c2784
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@ -214,31 +214,29 @@ static int ptrace_hbp_fill_attr_ctrl(unsigned int note_type,
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{
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int err, len, type, disabled = !ctrl.enabled;
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if (disabled) {
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len = 0;
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type = HW_BREAKPOINT_EMPTY;
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} else {
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err = arch_bp_generic_fields(ctrl, &len, &type);
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if (err)
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return err;
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attr->disabled = disabled;
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if (disabled)
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return 0;
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switch (note_type) {
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case NT_ARM_HW_BREAK:
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if ((type & HW_BREAKPOINT_X) != type)
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return -EINVAL;
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break;
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case NT_ARM_HW_WATCH:
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if ((type & HW_BREAKPOINT_RW) != type)
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return -EINVAL;
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break;
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default:
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err = arch_bp_generic_fields(ctrl, &len, &type);
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if (err)
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return err;
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switch (note_type) {
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case NT_ARM_HW_BREAK:
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if ((type & HW_BREAKPOINT_X) != type)
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return -EINVAL;
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}
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break;
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case NT_ARM_HW_WATCH:
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if ((type & HW_BREAKPOINT_RW) != type)
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return -EINVAL;
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break;
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default:
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return -EINVAL;
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}
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attr->bp_len = len;
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attr->bp_type = type;
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attr->disabled = disabled;
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return 0;
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}
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