[PATCH v2 4/5] powerpc/lib: Add LKDTM accessor for patching addr
From: Christopher M. Riedl <hidden>
Date: 2020-07-09 04:26:01
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
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 <redacted> --- 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