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Message-Id: <20240613-dev-andyc-dyn-ftrace-v4-v1-6-1a538e12c01e@sifive.com>
Date: Thu, 13 Jun 2024 15:11:11 +0800
From: Andy Chiu <andy.chiu@...ive.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
Alexandre Ghiti <alexghiti@...osinc.com>, Zong Li <zong.li@...ive.com>,
Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>, Mark Rutland <mark.rutland@....com>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>,
Puranjay Mohan <puranjay@...nel.org>
Cc: Palmer Dabbelt <palmer@...osinc.com>, linux-riscv@...ts.infradead.org,
linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
llvm@...ts.linux.dev, Andy Chiu <andy.chiu@...ive.com>
Subject: [PATCH 6/8] riscv: ftrace: do not use stop_machine to update code
Now it is safe to remove dependency from stop_machine() for us to patch
code in ftrace.
Signed-off-by: Andy Chiu <andy.chiu@...ive.com>
---
arch/riscv/kernel/ftrace.c | 53 ++++------------------------------------------
1 file changed, 4 insertions(+), 49 deletions(-)
diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
index f3b09f2d3ecc..9a421e151b1d 100644
--- a/arch/riscv/kernel/ftrace.c
+++ b/arch/riscv/kernel/ftrace.c
@@ -13,23 +13,13 @@
#include <asm/patch.h>
#ifdef CONFIG_DYNAMIC_FTRACE
-void ftrace_arch_code_modify_prepare(void) __acquires(&text_mutex)
+void arch_ftrace_update_code(int command)
{
mutex_lock(&text_mutex);
-
- /*
- * The code sequences we use for ftrace can't be patched while the
- * kernel is running, so we need to use stop_machine() to modify them
- * for now. This doesn't play nice with text_mutex, we use this flag
- * to elide the check.
- */
- riscv_patch_in_stop_machine = true;
-}
-
-void ftrace_arch_code_modify_post_process(void) __releases(&text_mutex)
-{
- riscv_patch_in_stop_machine = false;
+ command |= FTRACE_MAY_SLEEP;
+ ftrace_modify_all_code(command);
mutex_unlock(&text_mutex);
+ flush_icache_all();
}
static int ftrace_check_current_call(unsigned long hook_pos,
@@ -158,41 +148,6 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
return __ftrace_modify_call_site(&ftrace_call_dest, func, true);
}
-struct ftrace_modify_param {
- int command;
- atomic_t cpu_count;
-};
-
-static int __ftrace_modify_code(void *data)
-{
- struct ftrace_modify_param *param = data;
-
- if (atomic_inc_return(¶m->cpu_count) == num_online_cpus()) {
- ftrace_modify_all_code(param->command);
- /*
- * Make sure the patching store is effective *before* we
- * increment the counter which releases all waiting CPUs
- * by using the release variant of atomic increment. The
- * release pairs with the call to local_flush_icache_all()
- * on the waiting CPU.
- */
- atomic_inc_return_release(¶m->cpu_count);
- } else {
- while (atomic_read(¶m->cpu_count) <= num_online_cpus())
- cpu_relax();
- }
-
- local_flush_icache_all();
-
- return 0;
-}
-
-void arch_ftrace_update_code(int command)
-{
- struct ftrace_modify_param param = { command, ATOMIC_INIT(0) };
-
- stop_machine(__ftrace_modify_code, ¶m, cpu_online_mask);
-}
#endif
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
--
2.43.0
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