When live patching a STRICT_RWX kernel, a mapping is installed at a
"patching address" with temporary write permissions. Provide a
LKDTM-only accessor function for this address in preparation for a LKDTM
test which attempts to "hijack" this mapping by writing to it from
another CPU.
Signed-off-by: Christopher M. Riedl <cmr@xxxxxxxxxxxxxx>
---
arch/powerpc/include/asm/code-patching.h | 4 ++++
arch/powerpc/lib/code-patching.c | 7 +++++++
2 files changed, 11 insertions(+)
diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h
index eacc9102c251..ffc6dfdbbf8e 100644
--- a/arch/powerpc/include/asm/code-patching.h
+++ b/arch/powerpc/include/asm/code-patching.h
@@ -187,4 +187,8 @@ static inline unsigned long ppc_kallsyms_lookup_name(const char *name)
___PPC_RA(__REG_R1) | PPC_LR_STKOFF)
#endif /* CONFIG_PPC64 */
+#ifdef CONFIG_LKDTM
+unsigned long read_cpu_patching_addr(unsigned int cpu);
+#endif
+
#endif /* _ASM_POWERPC_CODE_PATCHING_H */
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 80fe3864f377..a12db2092947 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -51,6 +51,13 @@ int raw_patch_instruction(struct ppc_inst *addr, struct ppc_inst instr)
static struct mm_struct *patching_mm __ro_after_init;
static unsigned long patching_addr __ro_after_init;
+#ifdef CONFIG_LKDTM
+unsigned long read_cpu_patching_addr(unsigned int cpu)
+{
+ return patching_addr;
+}
+#endif
+
void __init poking_init(void)
{
spinlock_t *ptl; /* for protecting pte table */
--
2.27.0
