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Groups > linux.kernel > #1284688 > unrolled thread
| Started by | Li Bin <huawei.libin@huawei.com> |
|---|---|
| First post | 2015-12-06 03:10 +0100 |
| Last post | 2015-12-06 03:10 +0100 |
| Articles | 4 — 1 participant |
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[PATCH v2 0/5] ftrace: fix ftrace misleading comments for arch using it Li Bin <huawei.libin@huawei.com> - 2015-12-06 03:10 +0100
[PATCH v2 5/5] x86: ftrace: fix the comments for ftrace_modify_code_direct Li Bin <huawei.libin@huawei.com> - 2015-12-06 03:10 +0100
[PATCH v2 1/5] ia64: ftrace: fix the comments for ftrace_modify_code Li Bin <huawei.libin@huawei.com> - 2015-12-06 03:10 +0100
[PATCH v2 4/5] sh: ftrace: fix the comments for ftrace_modify_code Li Bin <huawei.libin@huawei.com> - 2015-12-06 03:10 +0100
| From | Li Bin <huawei.libin@huawei.com> |
|---|---|
| Date | 2015-12-06 03:10 +0100 |
| Subject | [PATCH v2 0/5] ftrace: fix ftrace misleading comments for arch using it |
| Message-ID | <qCwVY-GI-3@gated-at.bofh.it> |
Fix the following similar misleading comments of ftrace for arch ia64/metag/powerpc/sh/x86: Note: Due to modules and __init, code can disappear and change, we need to protect against faulting as well as code changing. We do this by using the probe_kernel_* functions. No real locking needed, this code is run through kstop_machine, or before SMP starts. Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: linux-ia64@vger.kernel.org Cc: James Hogan <james.hogan@imgtec.com> Cc: linux-metag@vger.kernel.org Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-sh@vger.kernel.org Cc: Thomas Gleixner <tglx@linutronix.de> "Cc: H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Li Bin (5): ia64: ftrace: fix the comments for ftrace_modify_code metag: ftrace: fix the comments for ftrace_modify_code powerpc: ftrace: fix the comments for ftrace_modify_code sh: ftrace: fix the comments for ftrace_modify_code x86: ftrace: fix the comments for ftrace_modify_code_direct arch/ia64/kernel/ftrace.c | 12 +++++------- arch/metag/kernel/ftrace.c | 11 +++++------ arch/powerpc/kernel/ftrace.c | 12 +++++------- arch/sh/kernel/ftrace.c | 12 +++++------- arch/x86/kernel/ftrace.c | 12 +++++------- 5 files changed, 25 insertions(+), 34 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Li Bin <huawei.libin@huawei.com> |
|---|---|
| Date | 2015-12-06 03:10 +0100 |
| Subject | [PATCH v2 5/5] x86: ftrace: fix the comments for ftrace_modify_code_direct |
| Message-ID | <qCwVZ-GI-19@gated-at.bofh.it> |
| In reply to | #1284688 |
There is no need to worry about module and __init text disappearing case, because that ftrace has a module notifier that is called when a module is being unloaded and before the text goes away and this code grabs the ftrace_lock mutex and removes the module functions from the ftrace list, such that it will no longer do any modifications to that module's text, the update to make functions be traced or not is done under the ftrace_lock mutex as well. And by now, __init section codes should not been modified by ftrace, because it is black listed in recordmcount.c and ignored by ftrace. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Li Bin <huawei.libin@huawei.com> --- arch/x86/kernel/ftrace.c | 12 +++++------- 1 files changed, 5 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 311bcf3..db0f6b1 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -106,13 +106,11 @@ ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code, unsigned char replaced[MCOUNT_INSN_SIZE]; /* - * Note: Due to modules and __init, code can - * disappear and change, we need to protect against faulting - * as well as code changing. We do this by using the - * probe_kernel_* functions. - * - * No real locking needed, this code is run through - * kstop_machine, or before SMP starts. + * Note: + * We are paranoid about modifying text, as if a bug was to happen, it + * could cause us to read or write to someplace that could cause harm. + * Carefully read and modify the code with probe_kernel_*(), and make + * sure what we read is what we expected it to be before modifying it. */ /* read the text we want to modify */ -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Li Bin <huawei.libin@huawei.com> |
|---|---|
| Date | 2015-12-06 03:10 +0100 |
| Subject | [PATCH v2 1/5] ia64: ftrace: fix the comments for ftrace_modify_code |
| Message-ID | <qCwVZ-GI-23@gated-at.bofh.it> |
| In reply to | #1284688 |
There is no need to worry about module and __init text disappearing case, because that ftrace has a module notifier that is called when a module is being unloaded and before the text goes away and this code grabs the ftrace_lock mutex and removes the module functions from the ftrace list, such that it will no longer do any modifications to that module's text, the update to make functions be traced or not is done under the ftrace_lock mutex as well. And by now, __init section codes should not been modified by ftrace, because it is black listed in recordmcount.c and ignored by ftrace. Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: linux-ia64@vger.kernel.org Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Li Bin <huawei.libin@huawei.com> --- arch/ia64/kernel/ftrace.c | 12 +++++------- 1 files changed, 5 insertions(+), 7 deletions(-) diff --git a/arch/ia64/kernel/ftrace.c b/arch/ia64/kernel/ftrace.c index 3b0c2aa..cee411e 100644 --- a/arch/ia64/kernel/ftrace.c +++ b/arch/ia64/kernel/ftrace.c @@ -97,13 +97,11 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code, unsigned char replaced[MCOUNT_INSN_SIZE]; /* - * Note: Due to modules and __init, code can - * disappear and change, we need to protect against faulting - * as well as code changing. We do this by using the - * probe_kernel_* functions. - * - * No real locking needed, this code is run through - * kstop_machine, or before SMP starts. + * Note: + * We are paranoid about modifying text, as if a bug was to happen, it + * could cause us to read or write to someplace that could cause harm. + * Carefully read and modify the code with probe_kernel_*(), and make + * sure what we read is what we expected it to be before modifying it. */ if (!do_check) -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Li Bin <huawei.libin@huawei.com> |
|---|---|
| Date | 2015-12-06 03:10 +0100 |
| Subject | [PATCH v2 4/5] sh: ftrace: fix the comments for ftrace_modify_code |
| Message-ID | <qCwVY-GI-17@gated-at.bofh.it> |
| In reply to | #1284688 |
There is no need to worry about module and __init text disappearing case, because that ftrace has a module notifier that is called when a module is being unloaded and before the text goes away and this code grabs the ftrace_lock mutex and removes the module functions from the ftrace list, such that it will no longer do any modifications to that module's text, the update to make functions be traced or not is done under the ftrace_lock mutex as well. And by now, __init section codes should not been modified by ftrace, because it is black listed in recordmcount.c and ignored by ftrace. Cc: linux-sh@vger.kernel.org Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Li Bin <huawei.libin@huawei.com> --- arch/sh/kernel/ftrace.c | 12 +++++------- 1 files changed, 5 insertions(+), 7 deletions(-) diff --git a/arch/sh/kernel/ftrace.c b/arch/sh/kernel/ftrace.c index 079d70e..38993e0 100644 --- a/arch/sh/kernel/ftrace.c +++ b/arch/sh/kernel/ftrace.c @@ -212,13 +212,11 @@ static int ftrace_modify_code(unsigned long ip, unsigned char *old_code, unsigned char replaced[MCOUNT_INSN_SIZE]; /* - * Note: Due to modules and __init, code can - * disappear and change, we need to protect against faulting - * as well as code changing. We do this by using the - * probe_kernel_* functions. - * - * No real locking needed, this code is run through - * kstop_machine, or before SMP starts. + * Note: + * We are paranoid about modifying text, as if a bug was to happen, it + * could cause us to read or write to someplace that could cause harm. + * Carefully read and modify the code with probe_kernel_*(), and make + * sure what we read is what we expected it to be before modifying it. */ /* read the text we want to modify */ -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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