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We implement regs_set_return_value() and override_function_with_return() for this purpose. On powerpc, a return from a function (blr) just branches to the location contained in the link register. So, we can just update pt_regs rather than redirecting execution to a dummy function that returns. Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Reviewed-by: Samuel Mendoza-Jonas <sam@mendozajonas.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
17 lines
470 B
C
17 lines
470 B
C
// SPDX-License-Identifier: GPL-2.0+
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#include <linux/error-injection.h>
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#include <linux/kprobes.h>
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#include <linux/uaccess.h>
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void override_function_with_return(struct pt_regs *regs)
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{
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/*
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* Emulate 'blr'. 'regs' represents the state on entry of a predefined
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* function in the kernel/module, captured on a kprobe. We don't need
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* to worry about 32-bit userspace on a 64-bit kernel.
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*/
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regs->nip = regs->link;
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}
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NOKPROBE_SYMBOL(override_function_with_return);
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