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powerpc/xmon: Don't allow breakpoints on suffixes

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Do not allow placing xmon breakpoints on the suffix of a prefix
instruction.

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
[mpe: Don't split printf strings across lines]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-27-jniethe5@gmail.com
This commit is contained in:
Jordan Niethe 2020-05-06 13:40:46 +10:00 committed by Michael Ellerman
parent 785b79d1e0
commit c9c831aebd
1 changed files with 25 additions and 2 deletions
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27
arch/powerpc/xmon/xmon.c
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@ -889,8 +889,8 @@ static struct bpt *new_breakpoint(unsigned long a)
static void insert_bpts(void) static void insert_bpts(void)
{ {
int i; int i;
struct ppc_inst instr; struct ppc_inst instr, instr2;
struct bpt *bp; struct bpt *bp, *bp2;
bp = bpts; bp = bpts;
for (i = 0; i < NBPTS; ++i, ++bp) { for (i = 0; i < NBPTS; ++i, ++bp) {
@ -908,6 +908,29 @@ static void insert_bpts(void)
bp->enabled = 0; bp->enabled = 0;
continue; continue;
} }
/*
* Check the address is not a suffix by looking for a prefix in
* front of it.
*/
if (mread_instr(bp->address - 4, &instr2) == 8) {
printf("Breakpoint at %lx is on the second word of a prefixed instruction, disabling it\n",
bp->address);
bp->enabled = 0;
continue;
}
/*
* We might still be a suffix - if the prefix has already been
* replaced by a breakpoint we won't catch it with the above
* test.
*/
bp2 = at_breakpoint(bp->address - 4);
if (bp2 && ppc_inst_prefixed(ppc_inst_read(bp2->instr))) {
printf("Breakpoint at %lx is on the second word of a prefixed instruction, disabling it\n",
bp->address);
bp->enabled = 0;
continue;
}
patch_instruction(bp->instr, instr); patch_instruction(bp->instr, instr);
patch_instruction((void *)bp->instr + ppc_inst_len(instr), patch_instruction((void *)bp->instr + ppc_inst_len(instr),
ppc_inst(bpinstr)); ppc_inst(bpinstr));