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powerpc/watchpoint: Prepare handler to handle more than one watchpoint

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Currently we assume that we have only one watchpoint supported by hw.
Get rid of that assumption and use dynamic loop instead. This should
make supporting more watchpoints very easy.

With more than one watchpoint, exception handler needs to know which
DAWR caused the exception, and hw currently does not provide it. So
we need sw logic for the same. To figure out which DAWR caused the
exception, check all different combinations of user specified range,
DAWR address range, actual access range and DAWRX constrains. For ex,
if user specified range and actual access range overlaps but DAWRX is
configured for readonly watchpoint and the instruction is store, this
DAWR must not have caused exception.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Reviewed-by: Michael Neuling <mikey@neuling.org>
[mpe: Unsplit multi-line printk() strings, fix some sparse warnings]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200514111741.97993-14-ravi.bangoria@linux.ibm.com
This commit is contained in:
Ravi Bangoria
2020-05-14 16:47:38 +05:30
committed by Michael Ellerman
parent e68ef121c1
commit 74c6881019
4 changed files with 312 additions and 94 deletions
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2
arch/powerpc/include/asm/processor.h
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@@ -185,7 +185,7 @@ struct thread_struct {
* Helps identify source of single-step exception and subsequent
* hw-breakpoint enablement
*/
struct perf_event *last_hit_ubp;
struct perf_event *last_hit_ubp[HBP_NUM_MAX];
#endif /* CONFIG_HAVE_HW_BREAKPOINT */
struct arch_hw_breakpoint hw_brk[HBP_NUM_MAX]; /* hardware breakpoint info */
unsigned long trap_nr; /* last trap # on this thread */