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Subject[PATCH v1 3/4] powerpc/code-patching: Use jump_label for testing freed initmem
Date
Once init is done, initmem is freed forever so no need to
test system_state at every call to patch_instruction().

Use jump_label.

This reduces by 2% the time needed to activate ftrace on an 8xx.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/include/asm/code-patching.h | 2 ++
arch/powerpc/lib/code-patching.c | 5 ++++-
arch/powerpc/mm/mem.c | 2 ++
3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h
index 409483b2d0ce..bccc3a538b9f 100644
--- a/arch/powerpc/include/asm/code-patching.h
+++ b/arch/powerpc/include/asm/code-patching.h
@@ -22,6 +22,8 @@
#define BRANCH_SET_LINK 0x1
#define BRANCH_ABSOLUTE 0x2

+DECLARE_STATIC_KEY_FALSE(init_mem_is_free);
+
bool is_offset_in_branch_range(long offset);
bool is_offset_in_cond_branch_range(long offset);
int create_branch(ppc_inst_t *instr, const u32 *addr,
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 62692c6031bc..ab434c3853c9 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -8,6 +8,7 @@
#include <linux/init.h>
#include <linux/cpuhotplug.h>
#include <linux/uaccess.h>
+#include <linux/jump_label.h>

#include <asm/tlbflush.h>
#include <asm/page.h>
@@ -193,10 +194,12 @@ static int do_patch_instruction(u32 *addr, ppc_inst_t instr)

#endif /* CONFIG_STRICT_KERNEL_RWX */

+__ro_after_init DEFINE_STATIC_KEY_FALSE(init_mem_is_free);
+
int patch_instruction(u32 *addr, ppc_inst_t instr)
{
/* Make sure we aren't patching a freed init section */
- if (system_state >= SYSTEM_FREEING_INITMEM && init_section_contains(addr, 4))
+ if (static_branch_likely(&init_mem_is_free) && init_section_contains(addr, 4))
return 0;

return do_patch_instruction(addr, instr);
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 8e301cd8925b..9710d4e0bf08 100644
--- 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/code-patching.h>

#include <mm/mmu_decl.h>

@@ -311,6 +312,7 @@ void free_initmem(void)
{
ppc_md.progress = ppc_printk_progress;
mark_initmem_nx();
+ static_branch_enable(&init_mem_is_free);
free_initmem_default(POISON_FREE_INITMEM);
}

--
2.35.1
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