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Subject[PATCH -v5mkII 13/17] arm/ftrace: Use __patch_text()
On Tue, Nov 12, 2019 at 11:29:51AM +0000, Will Deacon wrote:
> This fails to compile. I bodged it as below, but maybe this stuff should
> actually live in insn.c. Not fussed either way. I ran the ftrace tests,
> loaded a module and toggled ftrace on/off with this applied and it looks
> like it works to me:
>
> Tested-by: Will Deacon <will@kernel.org>

Thanks, I've folded that and will leave any further cleanup to some ARM
person that is capable of testing :-)

---
Subject: arm/ftrace: Use __patch_text()
From: Peter Zijlstra <peterz@infradead.org>
Date: Tue Oct 15 21:07:35 CEST 2019

Instead of flipping text protection, use the patch_text infrastructure
that uses a fixmap alias where required.

This removes the last user of set_all_modules_text_*().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Will Deacon <will@kernel.org>
Cc: rabin@rab.in
Cc: ard.biesheuvel@linaro.org
Cc: james.morse@arm.com
Cc: Mark Rutland <mark.rutland@arm.com>
---
arch/arm/kernel/Makefile | 4 ++--
arch/arm/kernel/ftrace.c | 10 ++--------
2 files changed, 4 insertions(+), 10 deletions(-)

--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -49,8 +49,8 @@ obj-$(CONFIG_HAVE_ARM_SCU) += smp_scu.o
obj-$(CONFIG_HAVE_ARM_TWD) += smp_twd.o
obj-$(CONFIG_ARM_ARCH_TIMER) += arch_timer.o
obj-$(CONFIG_FUNCTION_TRACER) += entry-ftrace.o
-obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o insn.o
-obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o insn.o
+obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o insn.o patch.o
+obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o insn.o patch.o
obj-$(CONFIG_JUMP_LABEL) += jump_label.o insn.o patch.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
# Main staffs in KPROBES are in arch/arm/probes/ .
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -22,6 +22,7 @@
#include <asm/ftrace.h>
#include <asm/insn.h>
#include <asm/set_memory.h>
+#include <asm/patch.h>

#ifdef CONFIG_THUMB2_KERNEL
#define NOP 0xf85deb04 /* pop.w {lr} */
@@ -35,9 +36,7 @@ static int __ftrace_modify_code(void *da
{
int *command = data;

- set_kernel_text_rw();
ftrace_modify_all_code(*command);
- set_kernel_text_ro();

return 0;
}
@@ -59,13 +58,11 @@ static unsigned long adjust_address(stru

int ftrace_arch_code_modify_prepare(void)
{
- set_all_modules_text_rw();
return 0;
}

int ftrace_arch_code_modify_post_process(void)
{
- set_all_modules_text_ro();
/* Make sure any TLB misses during machine stop are cleared. */
flush_tlb_all();
return 0;
@@ -97,10 +94,7 @@ static int ftrace_modify_code(unsigned l
return -EINVAL;
}

- if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE))
- return -EPERM;
-
- flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
+ __patch_text((void *)pc, new);

return 0;
}
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