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Date: Mon, 11 Nov 2019 18:19:55 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Will Deacon <will@...nel.org>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, rostedt@...dmis.org,
mhiramat@...nel.org, bristot@...hat.com, jbaron@...mai.com,
torvalds@...ux-foundation.org, tglx@...utronix.de,
mingo@...nel.org, namit@...are.com, hpa@...or.com, luto@...nel.org,
ard.biesheuvel@...aro.org, jpoimboe@...hat.com, jeyu@...nel.org,
alexei.starovoitov@...il.com, rabin@....in,
Mark Rutland <mark.rutland@....com>, james.morse@....com
Subject: Re: [PATCH -v5 13/17] arm/ftrace: Use __patch_text_real()
On Mon, Nov 11, 2019 at 04:47:03PM +0000, Will Deacon wrote:
> I'd still prefer to pass 'true' unconditionally here, since I don't think
> this is a hot path.
If you can give me a Tested-by, I'll replace it with the below... :-)
--- 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_real((void *)pc, new, true);
return 0;
}
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