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powerpc: Add support for function error injection

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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>
This commit is contained in:
Naveen N. Rao 2018-06-07 15:22:02 +05:30 • committed by Michael Ellerman
parent b4d16ab58c
commit 7cd01b08d3
5 changed files with 37 additions and 0 deletions
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16
arch/powerpc/lib/error-inject.c Normal file
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// SPDX-License-Identifier: GPL-2.0+
#include <linux/error-injection.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
void override_function_with_return(struct pt_regs *regs)
{
/*
* Emulate 'blr'. 'regs' represents the state on entry of a predefined
* function in the kernel/module, captured on a kprobe. We don't need
* to worry about 32-bit userspace on a 64-bit kernel.
*/
regs->nip = regs->link;
}
NOKPROBE_SYMBOL(override_function_with_return);