Re: [PATCH v5.18] powerpc/ftrace: Remove ftrace init tramp once kernel init is complete

[Greg KH]

On Mon, Jun 27, 2022 at 11:09:29PM +0530, Naveen N. Rao wrote:
> commit 84ade0a6655bee803d176525ef457175cbf4df22 upstream.
> 
> Stop using the ftrace trampoline for init section once kernel init is
> complete.
> 
> Fixes: 67361cf8071286 ("powerpc/ftrace: Handle large kernel configs")
> Cc: sta...@vger.kernel.org # v4.20+
> Signed-off-by: Naveen N. Rao 
> Signed-off-by: Michael Ellerman 
> Link: 
> https://lore.kernel.org/r/20220516071422.463738-1-naveen.n@linux.vnet.ibm.com
> ---
>  arch/powerpc/include/asm/ftrace.h  |  4 +++-
>  arch/powerpc/kernel/trace/ftrace.c | 15 ---
>  arch/powerpc/mm/mem.c  |  2 ++
>  3 files changed, 17 insertions(+), 4 deletions(-)

All now queued up, thanks.

greg k-h

[PATCH v5.18] powerpc/ftrace: Remove ftrace init tramp once kernel init is complete

[Naveen N. Rao]

commit 84ade0a6655bee803d176525ef457175cbf4df22 upstream.

Stop using the ftrace trampoline for init section once kernel init is
complete.

Fixes: 67361cf8071286 ("powerpc/ftrace: Handle large kernel configs")
Cc: sta...@vger.kernel.org # v4.20+
Signed-off-by: Naveen N. Rao 
Signed-off-by: Michael Ellerman 
Link: 
https://lore.kernel.org/r/20220516071422.463738-1-naveen.n@linux.vnet.ibm.com
---
 arch/powerpc/include/asm/ftrace.h  |  4 +++-
 arch/powerpc/kernel/trace/ftrace.c | 15 ---
 arch/powerpc/mm/mem.c  |  2 ++
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/ftrace.h 
b/arch/powerpc/include/asm/ftrace.h
index d83758acd1c7c3..44a37a2b6a1cfa 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -86,7 +86,7 @@ static inline bool arch_syscall_match_sym_name(const char 
*sym, const char *name
 #endif /* PPC64_ELF_ABI_v1 */
 #endif /* CONFIG_FTRACE_SYSCALLS */
 
-#ifdef CONFIG_PPC64
+#if defined(CONFIG_PPC64) && defined(CONFIG_FUNCTION_TRACER)
 #include 
 
 static inline void this_cpu_disable_ftrace(void)
@@ -110,11 +110,13 @@ static inline u8 this_cpu_get_ftrace_enabled(void)
return get_paca()->ftrace_enabled;
 }
 
+void ftrace_free_init_tramp(void);
 #else /* CONFIG_PPC64 */
 static inline void this_cpu_disable_ftrace(void) { }
 static inline void this_cpu_enable_ftrace(void) { }
 static inline void this_cpu_set_ftrace_enabled(u8 ftrace_enabled) { }
 static inline u8 this_cpu_get_ftrace_enabled(void) { return 1; }
+static inline void ftrace_free_init_tramp(void) { }
 #endif /* CONFIG_PPC64 */
 #endif /* !__ASSEMBLY__ */
 
diff --git a/arch/powerpc/kernel/trace/ftrace.c 
b/arch/powerpc/kernel/trace/ftrace.c
index 4ee04aacf9f13c..a778f2ae1f3f50 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -306,9 +306,7 @@ static int setup_mcount_compiler_tramp(unsigned long tramp)
 
/* Is this a known long jump tramp? */
for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
-   if (!ftrace_tramps[i])
-   break;
-   else if (ftrace_tramps[i] == tramp)
+   if (ftrace_tramps[i] == tramp)
return 0;
 
/* Is this a known plt tramp? */
@@ -863,6 +861,17 @@ void arch_ftrace_update_code(int command)
 
 extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
 
+void ftrace_free_init_tramp(void)
+{
+   int i;
+
+   for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
+   if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
+   ftrace_tramps[i] = 0;
+   return;
+   }
+}
+
 int __init ftrace_dyn_arch_init(void)
 {
int i;
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 4d221d033804ef..149635e5c16534 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -22,6 +22,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 
@@ -312,6 +313,7 @@ void free_initmem(void)
ppc_md.progress = ppc_printk_progress;
mark_initmem_nx();
free_initmem_default(POISON_FREE_INITMEM);
+   ftrace_free_init_tramp();
 }
 
 /*

base-commit: 7afbac05cb1c95e286ce97a40ee1c9f1791446c7
-- 
2.36.1