Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 fixes from Will Deacon:
"Three arm64 fixes for -rc4.
One of them is just a trivial documentation fix, whereas the other two
address a warning in the kexec code and a crash in ftrace on systems
implementing BTI.
The latter patch has a couple of ugly ifdefs which Mark plans to clean
up separately, but as-is the patch is straightforward for backporting
to stable kernels.
Summary:
- Add missing BTI landing instructions to the ftrace*_caller
trampolines
- Fix kexec() WARN when DEBUG_VIRTUAL is enabled
- Fix PAC documentation by removing stale references to compiler
flags"
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: ftrace: add missing BTIs
arm64: kexec: use __pa_symbol(empty_zero_page)
arm64: update PAC description for kernel
diff --git a/Documentation/arm64/pointer-authentication.rst b/Documentation/arm64/pointer-authentication.rst
index f127666..e5dad2e 100644
--- a/Documentation/arm64/pointer-authentication.rst
+++ b/Documentation/arm64/pointer-authentication.rst
@@ -53,11 +53,10 @@
virtual address size configured by the kernel. For example, with a
virtual address size of 48, the PAC is 7 bits wide.
-Recent versions of GCC can compile code with APIAKey-based return
-address protection when passed the -msign-return-address option. This
-uses instructions in the HINT space (unless -march=armv8.3-a or higher
-is also passed), and such code can run on systems without the pointer
-authentication extension.
+When ARM64_PTR_AUTH_KERNEL is selected, the kernel will be compiled
+with HINT space pointer authentication instructions protecting
+function returns. Kernels built with this option will work on hardware
+with or without pointer authentication support.
In addition to exec(), keys can also be reinitialized to random values
using the PR_PAC_RESET_KEYS prctl. A bitmask of PR_PAC_APIAKEY,
diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S
index b3e4f9a..8cf970d 100644
--- a/arch/arm64/kernel/entry-ftrace.S
+++ b/arch/arm64/kernel/entry-ftrace.S
@@ -77,11 +77,17 @@
.endm
SYM_CODE_START(ftrace_regs_caller)
+#ifdef BTI_C
+ BTI_C
+#endif
ftrace_regs_entry 1
b ftrace_common
SYM_CODE_END(ftrace_regs_caller)
SYM_CODE_START(ftrace_caller)
+#ifdef BTI_C
+ BTI_C
+#endif
ftrace_regs_entry 0
b ftrace_common
SYM_CODE_END(ftrace_caller)
diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index 1038494..6fb31c1 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -147,7 +147,7 @@ int machine_kexec_post_load(struct kimage *kimage)
if (rc)
return rc;
kimage->arch.ttbr1 = __pa(trans_pgd);
- kimage->arch.zero_page = __pa(empty_zero_page);
+ kimage->arch.zero_page = __pa_symbol(empty_zero_page);
reloc_size = __relocate_new_kernel_end - __relocate_new_kernel_start;
memcpy(reloc_code, __relocate_new_kernel_start, reloc_size);
