When live patching with STRICT_KERNEL_RWX 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 <c...@linux.ibm.com>
---
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 a95f63788c6b1..16fbc58a4932f 100644
--- a/arch/powerpc/include/asm/code-patching.h
+++ b/arch/powerpc/include/asm/code-patching.h
@@ -184,4 +184,8 @@ static inline unsigned long ppc_kallsyms_lookup_name(const
char *name)
#define PPC_INST_STD_LR PPC_RAW_STD(_R0, _R1, PPC_LR_STKOFF)
#endif /* CONFIG_PPC64 */
+#if IS_BUILTIN(CONFIG_LKDTM) && IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)
+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 f9a3019e37b43..54b6157d44e95 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -47,6 +47,13 @@ int raw_patch_instruction(u32 *addr, struct ppc_inst instr)
#ifdef CONFIG_STRICT_KERNEL_RWX
static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
+#if IS_BUILTIN(CONFIG_LKDTM)
+unsigned long read_cpu_patching_addr(unsigned int cpu)
+{
+ return (unsigned long)(per_cpu(text_poke_area, cpu))->addr;
+}
+#endif
+
static int text_area_cpu_up(unsigned int cpu)
{
struct vm_struct *area;
--
2.26.1
