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powerpc: Change calling convention for create_branch() et. al.

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create_branch(), create_cond_branch() and translate_branch() return the
instruction that they create, or return 0 to signal an error. Separate
these concerns in preparation for an instruction type that is not just
an unsigned int.  Fill the created instruction to a pointer passed as
the first parameter to the function and use a non-zero return value to
signify an error.

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-6-jniethe5@gmail.com
This commit is contained in:
Jordan Niethe
2020-05-06 13:40:25 +10:00
committed by Michael Ellerman
parent 5a7fdcab54
commit 7c95d8893f
6 changed files with 119 additions and 84 deletions
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24
arch/powerpc/kernel/optprobes.c
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@@ -251,15 +251,17 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
goto error;
}
branch_op_callback = create_branch((unsigned int *)buff + TMPL_CALL_HDLR_IDX,
(unsigned long)op_callback_addr,
BRANCH_SET_LINK);
rc = create_branch(&branch_op_callback,
(unsigned int *)buff + TMPL_CALL_HDLR_IDX,
(unsigned long)op_callback_addr,
BRANCH_SET_LINK);
branch_emulate_step = create_branch((unsigned int *)buff + TMPL_EMULATE_IDX,
(unsigned long)emulate_step_addr,
BRANCH_SET_LINK);
rc |= create_branch(&branch_emulate_step,
(unsigned int *)buff + TMPL_EMULATE_IDX,
(unsigned long)emulate_step_addr,
BRANCH_SET_LINK);
if (!branch_op_callback || !branch_emulate_step)
if (rc)
goto error;
patch_instruction(buff + TMPL_CALL_HDLR_IDX, branch_op_callback);
@@ -305,6 +307,7 @@ int arch_check_optimized_kprobe(struct optimized_kprobe *op)
void arch_optimize_kprobes(struct list_head *oplist)
{
unsigned int instr;
struct optimized_kprobe *op;
struct optimized_kprobe *tmp;
@@ -315,9 +318,10 @@ void arch_optimize_kprobes(struct list_head *oplist)
*/
memcpy(op->optinsn.copied_insn, op->kp.addr,
RELATIVEJUMP_SIZE);
patch_instruction(op->kp.addr,
create_branch((unsigned int *)op->kp.addr,
(unsigned long)op->optinsn.insn, 0));
create_branch(&instr,
(unsigned int *)op->kp.addr,
(unsigned long)op->optinsn.insn, 0);
patch_instruction(op->kp.addr, instr);
list_del_init(&op->list);
}
}