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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2020-10-28 17:15:27 -0400
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2020-11-13 12:15:28 -0500
commit2860cd8a235375df3c8ec8039d9fe5eb2f658b86 (patch)
treefdc9022ea4057f4d410d7b907b158d7cbb8787e8 /kernel/livepatch
parent02a474ca266a47ea8f4d5a11f4ffa120f83730ad (diff)
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 <jpoimboe@redhat.com> Cc: Jiri Kosina <jikos@kernel.org> Cc: live-patching@vger.kernel.org Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/livepatch')
-rw-r--r--kernel/livepatch/Kconfig2
-rw-r--r--kernel/livepatch/patch.c9
2 files changed, 6 insertions, 5 deletions
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;