Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 updates from Catalin Marinas:

 - arm64 perf: DDR PMU driver for Alibaba's T-Head Yitian 710 SoC, SVE
   vector granule register added to the user regs together with SVE perf
   extensions documentation.

 - SVE updates: add HWCAP for SVE EBF16, update the SVE ABI
   documentation to match the actual kernel behaviour (zeroing the
   registers on syscall rather than "zeroed or preserved" previously).

 - More conversions to automatic system registers generation.

 - vDSO: use self-synchronising virtual counter access in gettimeofday()
   if the architecture supports it.

 - arm64 stacktrace cleanups and improvements.

 - arm64 atomics improvements: always inline assembly, remove LL/SC
   trampolines.

 - Improve the reporting of EL1 exceptions: rework BTI and FPAC
   exception handling, better EL1 undefs reporting.

 - Cortex-A510 erratum 2658417: remove BF16 support due to incorrect
   result.

 - arm64 defconfig updates: build CoreSight as a module, enable options
   necessary for docker, memory hotplug/hotremove, enable all PMUs
   provided by Arm.

 - arm64 ptrace() support for TPIDR2_EL0 (register provided with the SME
   extensions).

 - arm64 ftraces updates/fixes: fix module PLTs with mcount, remove
   unused function.

 - kselftest updates for arm64: simple HWCAP validation, FP stress test
   improvements, validation of ZA regs in signal handlers, include
   larger SVE and SME vector lengths in signal tests, various cleanups.

 - arm64 alternatives (code patching) improvements to robustness and
   consistency: replace cpucap static branches with equivalent
   alternatives, associate callback alternatives with a cpucap.

 - Miscellaneous updates: optimise kprobe performance of patching
   single-step slots, simplify uaccess_mask_ptr(), move MTE registers
   initialisation to C, support huge vmalloc() mappings, run softirqs on
   the per-CPU IRQ stack, compat (arm32) misalignment fixups for
   multiword accesses.

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (126 commits)
  arm64: alternatives: Use vdso/bits.h instead of linux/bits.h
  arm64/kprobe: Optimize the performance of patching single-step slot
  arm64: defconfig: Add Coresight as module
  kselftest/arm64: Handle EINTR while reading data from children
  kselftest/arm64: Flag fp-stress as exiting when we begin finishing up
  kselftest/arm64: Don't repeat termination handler for fp-stress
  ARM64: reloc_test: add __init/__exit annotations to module init/exit funcs
  arm64/mm: fold check for KFENCE into can_set_direct_map()
  arm64: ftrace: fix module PLTs with mcount
  arm64: module: Remove unused plt_entry_is_initialized()
  arm64: module: Make plt_equals_entry() static
  arm64: fix the build with binutils 2.27
  kselftest/arm64: Don't enable v8.5 for MTE selftest builds
  arm64: uaccess: simplify uaccess_mask_ptr()
  arm64: asm/perf_regs.h: Avoid C++-style comment in UAPI header
  kselftest/arm64: Fix typo in hwcap check
  arm64: mte: move register initialization to C
  arm64: mm: handle ARM64_KERNEL_USES_PMD_MAPS in vmemmap_populate()
  arm64: dma: Drop cache invalidation from arch_dma_prep_coherent()
  arm64/sve: Add Perf extensions documentation
  ...

1 files changed, 16 insertions, 1 deletions

diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index 26789865748c..8745175f4a75 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -217,11 +217,26 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 	unsigned long pc = rec->ip;
 	u32 old = 0, new;
 
+	new = aarch64_insn_gen_nop();
+
+	/*
+	 * When using mcount, callsites in modules may have been initalized to
+	 * call an arbitrary module PLT (which redirects to the _mcount stub)
+	 * rather than the ftrace PLT we'll use at runtime (which redirects to
+	 * the ftrace trampoline). We can ignore the old PLT when initializing
+	 * the callsite.
+	 *
+	 * Note: 'mod' is only set at module load time.
+	 */
+	if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) &&
+	    IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) && mod) {
+		return aarch64_insn_patch_text_nosync((void *)pc, new);
+	}
+
 	if (!ftrace_find_callable_addr(rec, mod, &addr))
 		return -EINVAL;
 
 	old = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);
-	new = aarch64_insn_gen_nop();
 
 	return ftrace_modify_code(pc, old, new, true);
 }