[PATCH 5.18 5/6] powerpc/ftrace: Remove ftrace init tramp once kernel init is complete

Greg Kroah-Hartman
2022-06-30T14:13:27Z

From: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>

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: stable@vger.kernel.org # v4.20+
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220516071422.463738-1-naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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(-)

--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -86,7 +86,7 @@ static inline bool arch_syscall_match_sy
#endif /* PPC64_ELF_ABI_v1 */
#endif /* CONFIG_FTRACE_SYSCALLS */

-#ifdef CONFIG_PPC64
+#if defined(CONFIG_PPC64) && defined(CONFIG_FUNCTION_TRACER)
#include <asm/paca.h>

static inline void this_cpu_disable_ftrace(void)
@@ -110,11 +110,13 @@ static inline u8 this_cpu_get_ftrace_ena
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__ */

--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -306,9 +306,7 @@ static int setup_mcount_compiler_tramp(u

/* 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;
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -22,6 +22,7 @@
#include <asm/kasan.h>
#include <asm/svm.h>
#include <asm/mmzone.h>
+#include <asm/ftrace.h>

#include <mm/mmu_decl.h>

@@ -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();
}

/*