From 2f7c68cb55ecb7331f2381deb497c27155f32faf Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Wed, 03 Jan 2024 09:43:39 +0000
Subject: [PATCH] update kernel to 5.10.198
---
kernel/arch/riscv/kernel/patch.c | 28 +++++++++++++++++++++++++---
1 files changed, 25 insertions(+), 3 deletions(-)
diff --git a/kernel/arch/riscv/kernel/patch.c b/kernel/arch/riscv/kernel/patch.c
index 1612e11..c3fced4 100644
--- a/kernel/arch/riscv/kernel/patch.c
+++ b/kernel/arch/riscv/kernel/patch.c
@@ -11,6 +11,7 @@
#include <asm/kprobes.h>
#include <asm/cacheflush.h>
#include <asm/fixmap.h>
+#include <asm/ftrace.h>
#include <asm/patch.h>
struct patch_insn {
@@ -18,6 +19,8 @@
u32 insn;
atomic_t cpu_count;
};
+
+int riscv_patch_in_stop_machine = false;
#ifdef CONFIG_MMU
static void *patch_map(void *addr, int fixmap)
@@ -55,8 +58,15 @@
* Before reaching here, it was expected to lock the text_mutex
* already, so we don't need to give another lock here and could
* ensure that it was safe between each cores.
+ *
+ * We're currently using stop_machine() for ftrace & kprobes, and while
+ * that ensures text_mutex is held before installing the mappings it
+ * does not ensure text_mutex is held by the calling thread. That's
+ * safe but triggers a lockdep failure, so just elide it for that
+ * specific case.
*/
- lockdep_assert_held(&text_mutex);
+ if (!riscv_patch_in_stop_machine)
+ lockdep_assert_held(&text_mutex);
if (across_pages)
patch_map(addr + len, FIX_TEXT_POKE1);
@@ -117,13 +127,25 @@
int patch_text(void *addr, u32 insn)
{
+ int ret;
struct patch_insn patch = {
.addr = addr,
.insn = insn,
.cpu_count = ATOMIC_INIT(0),
};
- return stop_machine_cpuslocked(patch_text_cb,
- &patch, cpu_online_mask);
+ /*
+ * kprobes takes text_mutex, before calling patch_text(), but as we call
+ * calls stop_machine(), the lockdep assertion in patch_insn_write()
+ * gets confused by the context in which the lock is taken.
+ * Instead, ensure the lock is held before calling stop_machine(), and
+ * set riscv_patch_in_stop_machine to skip the check in
+ * patch_insn_write().
+ */
+ lockdep_assert_held(&text_mutex);
+ riscv_patch_in_stop_machine = true;
+ ret = stop_machine_cpuslocked(patch_text_cb, &patch, cpu_online_mask);
+ riscv_patch_in_stop_machine = false;
+ return ret;
}
NOKPROBE_SYMBOL(patch_text);
--
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