linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "tip-bot2 for Naveen N. Rao" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: perf/core] kprobes: Do not increment probe miss count in the fault handler
Date: Fri, 04 Jun 2021 13:38:41 -0000	[thread overview]
Message-ID: <162281392181.29796.17357169645855038512.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20210601120150.672652-1-naveen.n.rao@linux.vnet.ibm.com>

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     2e38eb04c95e5546b71bb86ee699a891c7d212b5
Gitweb:        https://git.kernel.org/tip/2e38eb04c95e5546b71bb86ee699a891c7d212b5
Author:        Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
AuthorDate:    Tue, 01 Jun 2021 17:31:50 +05:30
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 03 Jun 2021 15:47:26 +02:00

kprobes: Do not increment probe miss count in the fault handler

Kprobes has a counter 'nmissed', that is used to count the number of
times a probe handler was not called. This generally happens when we hit
a kprobe while handling another kprobe.

However, if one of the probe handlers causes a fault, we are currently
incrementing 'nmissed'. The comment in fault handler indicates that this
can be used to account faults taken by the probe handlers. But, this has
never been the intention as is evident from the comment above 'nmissed'
in 'struct kprobe':

	/*count the number of times this probe was temporarily disarmed */
	unsigned long nmissed;

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lkml.kernel.org/r/20210601120150.672652-1-naveen.n.rao@linux.vnet.ibm.com
---
 arch/arc/kernel/kprobes.c          |  6 ------
 arch/arm/probes/kprobes/core.c     | 14 --------------
 arch/arm64/kernel/probes/kprobes.c |  7 -------
 arch/csky/kernel/probes/kprobes.c  |  7 -------
 arch/ia64/kernel/kprobes.c         |  7 -------
 arch/powerpc/kernel/kprobes.c      |  7 -------
 arch/riscv/kernel/probes/kprobes.c |  7 -------
 arch/s390/kernel/kprobes.c         |  7 -------
 arch/sh/kernel/kprobes.c           |  7 -------
 arch/sparc/kernel/kprobes.c        |  7 -------
 arch/x86/kernel/kprobes/core.c     |  8 --------
 11 files changed, 84 deletions(-)

diff --git a/arch/arc/kernel/kprobes.c b/arch/arc/kernel/kprobes.c
index 9f5b39f..5f0415f 100644
--- a/arch/arc/kernel/kprobes.c
+++ b/arch/arc/kernel/kprobes.c
@@ -317,12 +317,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned long trapnr)
 		 * caused the fault.
 		 */
 
-		/* We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accounting
-		 * these specific fault cases.
-		 */
-		kprobes_inc_nmissed_count(cur);
-
 		/*
 		 * In case the user-specified fault handler returned zero,
 		 * try to fix up.
diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c
index 7b9b9a5..27e0af7 100644
--- a/arch/arm/probes/kprobes/core.c
+++ b/arch/arm/probes/kprobes/core.c
@@ -348,20 +348,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr)
 			reset_current_kprobe();
 		}
 		break;
-
-	case KPROBE_HIT_ACTIVE:
-	case KPROBE_HIT_SSDONE:
-		/*
-		 * We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accounting
-		 * these specific fault cases.
-		 */
-		kprobes_inc_nmissed_count(cur);
-
-		break;
-
-	default:
-		break;
 	}
 
 	return 0;
diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
index f6b088e..004b86e 100644
--- a/arch/arm64/kernel/probes/kprobes.c
+++ b/arch/arm64/kernel/probes/kprobes.c
@@ -277,13 +277,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr)
 	case KPROBE_HIT_ACTIVE:
 	case KPROBE_HIT_SSDONE:
 		/*
-		 * We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accounting
-		 * these specific fault cases.
-		 */
-		kprobes_inc_nmissed_count(cur);
-
-		/*
 		 * In case the user-specified fault handler returned
 		 * zero, try to fix up.
 		 */
diff --git a/arch/csky/kernel/probes/kprobes.c b/arch/csky/kernel/probes/kprobes.c
index e0e973e..68b22b4 100644
--- a/arch/csky/kernel/probes/kprobes.c
+++ b/arch/csky/kernel/probes/kprobes.c
@@ -295,13 +295,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr)
 	case KPROBE_HIT_ACTIVE:
 	case KPROBE_HIT_SSDONE:
 		/*
-		 * We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accounting
-		 * these specific fault cases.
-		 */
-		kprobes_inc_nmissed_count(cur);
-
-		/*
 		 * In case the user-specified fault handler returned
 		 * zero, try to fix up.
 		 */
diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index 6efed4e..441ed04 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -844,13 +844,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 	case KPROBE_HIT_ACTIVE:
 	case KPROBE_HIT_SSDONE:
 		/*
-		 * We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accounting
-		 * these specific fault cases.
-		 */
-		kprobes_inc_nmissed_count(cur);
-
-		/*
 		 * In case the user-specified fault handler returned
 		 * zero, try to fix up.
 		 */
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 75b4e87..3f70083 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -502,13 +502,6 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 	case KPROBE_HIT_ACTIVE:
 	case KPROBE_HIT_SSDONE:
 		/*
-		 * We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accounting
-		 * these specific fault cases.
-		 */
-		kprobes_inc_nmissed_count(cur);
-
-		/*
 		 * In case the user-specified fault handler returned
 		 * zero, try to fix up.
 		 */
diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/kprobes.c
index 923b5ea..9b71a63 100644
--- a/arch/riscv/kernel/probes/kprobes.c
+++ b/arch/riscv/kernel/probes/kprobes.c
@@ -277,13 +277,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr)
 	case KPROBE_HIT_ACTIVE:
 	case KPROBE_HIT_SSDONE:
 		/*
-		 * We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accounting
-		 * these specific fault cases.
-		 */
-		kprobes_inc_nmissed_count(cur);
-
-		/*
 		 * In case the user-specified fault handler returned
 		 * zero, try to fix up.
 		 */
diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index ad631e3..74b0bd2 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -446,13 +446,6 @@ static int kprobe_trap_handler(struct pt_regs *regs, int trapnr)
 	case KPROBE_HIT_ACTIVE:
 	case KPROBE_HIT_SSDONE:
 		/*
-		 * We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accounting
-		 * these specific fault cases.
-		 */
-		kprobes_inc_nmissed_count(p);
-
-		/*
 		 * In case the user-specified fault handler returned
 		 * zero, try to fix up.
 		 */
diff --git a/arch/sh/kernel/kprobes.c b/arch/sh/kernel/kprobes.c
index 5826342..1c7f358 100644
--- a/arch/sh/kernel/kprobes.c
+++ b/arch/sh/kernel/kprobes.c
@@ -383,13 +383,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 	case KPROBE_HIT_ACTIVE:
 	case KPROBE_HIT_SSDONE:
 		/*
-		 * We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accounting
-		 * these specific fault cases.
-		 */
-		kprobes_inc_nmissed_count(cur);
-
-		/*
 		 * In case the user-specified fault handler returned
 		 * zero, try to fix up.
 		 */
diff --git a/arch/sparc/kernel/kprobes.c b/arch/sparc/kernel/kprobes.c
index db4e341..4c05a4e 100644
--- a/arch/sparc/kernel/kprobes.c
+++ b/arch/sparc/kernel/kprobes.c
@@ -346,13 +346,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 	case KPROBE_HIT_ACTIVE:
 	case KPROBE_HIT_SSDONE:
 		/*
-		 * We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accounting
-		 * these specific fault cases.
-		 */
-		kprobes_inc_nmissed_count(cur);
-
-		/*
 		 * In case the user-specified fault handler returned
 		 * zero, try to fix up.
 		 */
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index cfcdf4b..1b3fe0e 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -1102,14 +1102,6 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 			restore_previous_kprobe(kcb);
 		else
 			reset_current_kprobe();
-	} else if (kcb->kprobe_status == KPROBE_HIT_ACTIVE ||
-		   kcb->kprobe_status == KPROBE_HIT_SSDONE) {
-		/*
-		 * We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accounting
-		 * these specific fault cases.
-		 */
-		kprobes_inc_nmissed_count(cur);
 	}
 
 	return 0;

  parent reply	other threads:[~2021-06-04 13:38 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-25  7:25 [PATCH 0/2] kprobes: Remove kprobe::fault_handler Peter Zijlstra
2021-05-25  7:25 ` [PATCH 1/2] " Peter Zijlstra
2021-05-25 14:06   ` Masami Hiramatsu
2021-05-26 10:50   ` Naveen N. Rao
2021-05-26 13:51     ` Masami Hiramatsu
2021-06-01 12:01   ` [PATCH] kprobes: Do not increment probe miss count in the fault handler Naveen N. Rao
2021-06-01 13:20     ` Peter Zijlstra
2021-06-01 23:48       ` Masami Hiramatsu
2021-06-04 13:38     ` tip-bot2 for Naveen N. Rao [this message]
2021-06-01 14:04   ` [tip: perf/core] kprobes: Remove kprobe::fault_handler tip-bot2 for Peter Zijlstra
2021-05-25  7:25 ` [PATCH 2/2] x86,kprobes: WARN if kprobes tries to handle a fault Peter Zijlstra
2021-05-25 14:21   ` Masami Hiramatsu
2021-06-01 14:04   ` [tip: perf/core] " tip-bot2 for Peter Zijlstra

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=162281392181.29796.17357169645855038512.tip-bot2@tip-bot2 \
    --to=tip-bot2@linutronix.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-tip-commits@vger.kernel.org \
    --cc=mhiramat@kernel.org \
    --cc=naveen.n.rao@linux.vnet.ibm.com \
    --cc=peterz@infradead.org \
    --cc=x86@kernel.org \
    --subject='Re: [tip: perf/core] kprobes: Do not increment probe miss count in the fault handler' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).