From 7b7b8a2c9560efb5874ea1d84d1dce5ba4c8c487 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Thu, 15 Oct 2020 20:10:28 -0700 Subject: kernel/: fix repeated words in comments Fix multiple occurrences of duplicated words in kernel/. Fix one typo/spello on the same line as a duplicate word. Change one instance of "the the" to "that the". Otherwise just drop one of the repeated words. Signed-off-by: Randy Dunlap Signed-off-by: Andrew Morton Link: https://lkml.kernel.org/r/98202fa6-8919-ef63-9efe-c0fad5ca7af1@infradead.org Signed-off-by: Linus Torvalds --- kernel/livepatch/state.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/livepatch') diff --git a/kernel/livepatch/state.c b/kernel/livepatch/state.c index 7ee19476de9d..2565d039ade0 100644 --- a/kernel/livepatch/state.c +++ b/kernel/livepatch/state.c @@ -55,7 +55,7 @@ EXPORT_SYMBOL_GPL(klp_get_state); * * The function can be called only during transition when a new * livepatch is being enabled or when such a transition is reverted. - * It is typically called only from from pre/post (un)patch + * It is typically called only from pre/post (un)patch * callbacks. * * Return: pointer to the latest struct klp_state from already -- cgit v1.2.3 From 13f3ea9a2c829f28610bb8772a8b9c328412930e Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Thu, 5 Nov 2020 21:32:41 -0500 Subject: livepatch/ftrace: Add recursion protection to the ftrace callback If a ftrace callback does not supply its own recursion protection and does not set the RECURSION_SAFE flag in its ftrace_ops, then ftrace will make a helper trampoline to do so before calling the callback instead of just calling the callback directly. The default for ftrace_ops is going to change. It will expect that handlers provide their own recursion protection, unless its ftrace_ops states otherwise. Link: https://lkml.kernel.org/r/20201028115613.291169246@goodmis.org Link: https://lkml.kernel.org/r/20201106023547.122802424@goodmis.org Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Masami Hiramatsu Cc: Andrew Morton Cc: Josh Poimboeuf Cc: Jiri Kosina Cc: Joe Lawrence Cc: live-patching@vger.kernel.org Reviewed-by: Petr Mladek Acked-by: Miroslav Benes Signed-off-by: Steven Rostedt (VMware) --- kernel/livepatch/patch.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'kernel/livepatch') diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c index b552cf2d85f8..6c0164d24bbd 100644 --- a/kernel/livepatch/patch.c +++ b/kernel/livepatch/patch.c @@ -45,9 +45,13 @@ static void notrace klp_ftrace_handler(unsigned long ip, struct klp_ops *ops; struct klp_func *func; int patch_state; + int bit; ops = container_of(fops, struct klp_ops, fops); + bit = ftrace_test_recursion_trylock(); + if (bit < 0) + return; /* * A variant of synchronize_rcu() is used to allow patching functions * where RCU is not watching, see klp_synchronize_transition(). @@ -117,6 +121,7 @@ static void notrace klp_ftrace_handler(unsigned long ip, unlock: preempt_enable_notrace(); + ftrace_test_recursion_unlock(bit); } /* -- cgit v1.2.3 From 4b750b573c5b3ee10e33c1573eaa94a9dad62f19 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Thu, 5 Nov 2020 21:32:42 -0500 Subject: livepatch: Trigger WARNING if livepatch function fails due to recursion If for some reason a function is called that triggers the recursion detection of live patching, trigger a warning. By not executing the live patch code, it is possible that the old unpatched function will be called placing the system into an unknown state. Link: https://lore.kernel.org/r/20201029145709.GD16774@alley Link: https://lkml.kernel.org/r/20201106023547.312639435@goodmis.org Cc: Masami Hiramatsu Cc: Andrew Morton Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Josh Poimboeuf Cc: Jiri Kosina Cc: Joe Lawrence Cc: live-patching@vger.kernel.org Suggested-by: Miroslav Benes Reviewed-by: Petr Mladek Acked-by: Miroslav Benes Signed-off-by: Steven Rostedt (VMware) --- kernel/livepatch/patch.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/livepatch') diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c index 6c0164d24bbd..15480bf3ce88 100644 --- a/kernel/livepatch/patch.c +++ b/kernel/livepatch/patch.c @@ -50,7 +50,7 @@ static void notrace klp_ftrace_handler(unsigned long ip, ops = container_of(fops, struct klp_ops, fops); bit = ftrace_test_recursion_trylock(); - if (bit < 0) + if (WARN_ON_ONCE(bit < 0)) return; /* * A variant of synchronize_rcu() is used to allow patching functions -- cgit v1.2.3 From 773c16705058e9be7b0f4ce124e89cd231c120a2 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Thu, 5 Nov 2020 21:32:46 -0500 Subject: ftrace: Add recording of functions that caused recursion This adds CONFIG_FTRACE_RECORD_RECURSION that will record to a file "recursed_functions" all the functions that caused recursion while a callback to the function tracer was running. Link: https://lkml.kernel.org/r/20201106023548.102375687@goodmis.org Cc: Masami Hiramatsu Cc: Andrew Morton Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Guo Ren Cc: "James E.J. Bottomley" Cc: Helge Deller Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Christian Borntraeger Cc: Thomas Gleixner Cc: Borislav Petkov Cc: x86@kernel.org Cc: "H. Peter Anvin" Cc: Kees Cook Cc: Anton Vorontsov Cc: Colin Cross Cc: Tony Luck Cc: Josh Poimboeuf Cc: Jiri Kosina Cc: Miroslav Benes Cc: Petr Mladek Cc: Joe Lawrence Cc: Kamalesh Babulal Cc: Mauro Carvalho Chehab Cc: Sebastian Andrzej Siewior Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-csky@vger.kernel.org Cc: linux-parisc@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-s390@vger.kernel.org Cc: live-patching@vger.kernel.org Signed-off-by: Steven Rostedt (VMware) --- kernel/livepatch/patch.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/livepatch') diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c index 15480bf3ce88..875c5dbbdd33 100644 --- a/kernel/livepatch/patch.c +++ b/kernel/livepatch/patch.c @@ -49,7 +49,7 @@ static void notrace klp_ftrace_handler(unsigned long ip, ops = container_of(fops, struct klp_ops, fops); - bit = ftrace_test_recursion_trylock(); + bit = ftrace_test_recursion_trylock(ip, parent_ip); if (WARN_ON_ONCE(bit < 0)) return; /* -- cgit v1.2.3 From d19ad0775dcd64b49eecf4fa79c17959ebfbd26b Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Wed, 28 Oct 2020 17:42:17 -0400 Subject: ftrace: Have the callbacks receive a struct ftrace_regs instead of pt_regs In preparation to have arguments of a function passed to callbacks attached to functions as default, change the default callback prototype to receive a struct ftrace_regs as the forth parameter instead of a pt_regs. For callbacks that set the FL_SAVE_REGS flag in their ftrace_ops flags, they will now need to get the pt_regs via a ftrace_get_regs() helper call. If this is called by a callback that their ftrace_ops did not have a FL_SAVE_REGS flag set, it that helper function will return NULL. This will allow the ftrace_regs to hold enough just to get the parameters and stack pointer, but without the worry that callbacks may have a pt_regs that is not completely filled. Acked-by: Peter Zijlstra (Intel) Reviewed-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- kernel/livepatch/patch.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel/livepatch') diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c index 875c5dbbdd33..f89f9e7e9b07 100644 --- a/kernel/livepatch/patch.c +++ b/kernel/livepatch/patch.c @@ -40,8 +40,9 @@ struct klp_ops *klp_find_ops(void *old_func) static void notrace klp_ftrace_handler(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *fops, - struct pt_regs *regs) + struct ftrace_regs *fregs) { + struct pt_regs *regs = ftrace_get_regs(fregs); struct klp_ops *ops; struct klp_func *func; int patch_state; -- cgit v1.2.3 From 2860cd8a235375df3c8ec8039d9fe5eb2f658b86 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Wed, 28 Oct 2020 17:15:27 -0400 Subject: livepatch: Use the default ftrace_ops instead of REGS when ARGS is available When CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS is available, the ftrace call will be able to set the ip of the calling function. This will improve the performance of live kernel patching where it does not need all the regs to be stored just to change the instruction pointer. If all archs that support live kernel patching also support HAVE_DYNAMIC_FTRACE_WITH_ARGS, then the architecture specific function klp_arch_set_pc() could be made generic. It is possible that an arch can support HAVE_DYNAMIC_FTRACE_WITH_ARGS but not HAVE_DYNAMIC_FTRACE_WITH_REGS and then have access to live patching. Cc: Josh Poimboeuf Cc: Jiri Kosina Cc: live-patching@vger.kernel.org Acked-by: Peter Zijlstra (Intel) Acked-by: Miroslav Benes Signed-off-by: Steven Rostedt (VMware) --- kernel/livepatch/Kconfig | 2 +- kernel/livepatch/patch.c | 9 +++++---- 2 files changed, 6 insertions(+), 5 deletions(-) (limited to 'kernel/livepatch') diff --git a/kernel/livepatch/Kconfig b/kernel/livepatch/Kconfig index 54102deb50ba..53d51ed619a3 100644 --- a/kernel/livepatch/Kconfig +++ b/kernel/livepatch/Kconfig @@ -6,7 +6,7 @@ config HAVE_LIVEPATCH config LIVEPATCH bool "Kernel Live Patching" - depends on DYNAMIC_FTRACE_WITH_REGS + depends on DYNAMIC_FTRACE_WITH_REGS || DYNAMIC_FTRACE_WITH_ARGS depends on MODULES depends on SYSFS depends on KALLSYMS_ALL diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c index f89f9e7e9b07..e8029aea67f1 100644 --- a/kernel/livepatch/patch.c +++ b/kernel/livepatch/patch.c @@ -42,7 +42,6 @@ static void notrace klp_ftrace_handler(unsigned long ip, struct ftrace_ops *fops, struct ftrace_regs *fregs) { - struct pt_regs *regs = ftrace_get_regs(fregs); struct klp_ops *ops; struct klp_func *func; int patch_state; @@ -118,7 +117,7 @@ static void notrace klp_ftrace_handler(unsigned long ip, if (func->nop) goto unlock; - klp_arch_set_pc(regs, (unsigned long)func->new_func); + klp_arch_set_pc(fregs, (unsigned long)func->new_func); unlock: preempt_enable_notrace(); @@ -200,8 +199,10 @@ static int klp_patch_func(struct klp_func *func) return -ENOMEM; ops->fops.func = klp_ftrace_handler; - ops->fops.flags = FTRACE_OPS_FL_SAVE_REGS | - FTRACE_OPS_FL_DYNAMIC | + ops->fops.flags = FTRACE_OPS_FL_DYNAMIC | +#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS + FTRACE_OPS_FL_SAVE_REGS | +#endif FTRACE_OPS_FL_IPMODIFY | FTRACE_OPS_FL_PERMANENT; -- cgit v1.2.3