[PATCH 4/9] arm64: alternatives: hoist print out of __apply_alternatives()

Mark Rutland
2022-09-01T15:15:50Z

Printing in the middle of __apply_alternatives() is potentially unsafe
and not all that helpful given these days we practically always patch
*something*.

Hoist the print out of __apply_alternatives(), and add separate prints
to __apply_alternatives() and apply_alternatives_all(), which will make
it easier to spot if either patching call goes wrong.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
---
arch/arm64/kernel/alternative.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
index 9bcaa5eacf16c..d94d97cb4a0bf 100644
--- a/arch/arm64/kernel/alternative.c
+++ b/arch/arm64/kernel/alternative.c
@@ -156,8 +156,6 @@ static void __nocfi __apply_alternatives(struct alt_region *region, bool is_modu
else
BUG_ON(alt->alt_len != alt->orig_len);

- pr_info_once("patching kernel code\n");
-
origptr = ALT_ORIG_PTR(alt);
updptr = is_module ? origptr : lm_alias(origptr);
nr_inst = alt->orig_len / AARCH64_INSN_SIZE;
@@ -225,6 +223,8 @@ static int __apply_alternatives_multi_stop(void *unused)

void __init apply_alternatives_all(void)
{
+ pr_info("applying system-wide alternatives\n");
+
/* better not try code patching on a live SMP system */
stop_machine(__apply_alternatives_multi_stop, NULL, cpu_online_mask);
}
@@ -244,6 +244,8 @@ void __init apply_boot_alternatives(void)
/* If called on non-boot cpu things could go wrong */
WARN_ON(smp_processor_id() != 0);

+ pr_info("applying boot alternatives\n");
+
__apply_alternatives(&region, false, &boot_capabilities[0]);
}