[PATCH v4 6/7] riscv: Kconfig: enable HAVE_RELIABLE_STACKTRACE and HAVE_LIVEPATCH

[Wang Han <wanghan@linux.alibaba.com>]

Now that the metadata frame records, the kunwind state machine and
arch_stack_walk_reliable() are all in place, advertise the capability
to the rest of the kernel:

  * select HAVE_RELIABLE_STACKTRACE under FRAME_POINTER && 64BIT, so
    only the configurations with the tested metadata records and
    FP-based reliable walker enable it.
  * select HAVE_LIVEPATCH under the same condition and source
    kernel/livepatch/Kconfig so the livepatch menu is reachable from
    the RISC-V configuration.

The 64BIT dependency is conservative scoping rather than a hard
technical requirement: the metadata frame record, kunwind state machine
and arch_stack_walk_reliable() also build on RV32, and the IRQ-stack
frame-record adjustment fixes a latent RV32 issue. However, the syscall
livepatch selftest and module relocation path have only been exercised
on RV64 QEMU virt so far. The 64BIT gate can be relaxed in a follow-up
once RV32 has equivalent coverage.

This is split out from the unwinder change so the policy decision and
the implementation can be reviewed and reverted independently.

Reviewed-by: Shuai Xue <xueshuai@linux.alibaba.com>
Signed-off-by: Wang Han <wanghan@linux.alibaba.com>
---
 arch/riscv/Kconfig | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index cb3d85abf595..4d09fab682ac 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -186,6 +186,7 @@ config RISCV
 	select HAVE_KRETPROBES
 	# https://github.com/ClangBuiltLinux/linux/issues/1881
 	select HAVE_LD_DEAD_CODE_DATA_ELIMINATION if !LD_IS_LLD
+	select HAVE_LIVEPATCH if FRAME_POINTER && 64BIT
 	select HAVE_MOVE_PMD
 	select HAVE_MOVE_PUD
 	select HAVE_PAGE_SIZE_4KB
@@ -196,6 +197,7 @@ config RISCV
 	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
 	select HAVE_PREEMPT_DYNAMIC_KEY
 	select HAVE_REGS_AND_STACK_ACCESS_API
+	select HAVE_RELIABLE_STACKTRACE if FRAME_POINTER && 64BIT
 	select HAVE_RETHOOK
 	select HAVE_RSEQ
 	select HAVE_RUST if RUSTC_SUPPORTS_RISCV && CC_IS_CLANG
@@ -1392,3 +1394,5 @@ endmenu # "CPU Power Management"
 source "arch/riscv/kvm/Kconfig"
 
 source "drivers/acpi/Kconfig"
+
+source "kernel/livepatch/Kconfig"
-- 
2.43.0