From: "Steven Rostedt (VMware)" <[email protected]> In an effort to enable -Wcast-function-type in the top-level Makefile to support Control Flow Integrity builds, all function casts need to be removed.
This means that ftrace_ops_list_func() can no longer be defined as ftrace_ops_no_ops(). The reason for ftrace_ops_no_ops() is to use that when an architecture calls ftrace_ops_list_func() with only two parameters (called from assembly). And to make sure there's no C side-effects, those archs call ftrace_ops_no_ops() which only has two parameters, as ftrace_ops_list_func() has four parameters. Instead of a typecast, use vmlinux.lds.h to define ftrace_ops_list_func() to arch_ftrace_ops_list_func() that will define the proper set of parameters. Link: https://lore.kernel.org/r/[email protected] Requested-by: Oscar Carter <[email protected]> Signed-off-by: Steven Rostedt (VMware) <[email protected]> --- include/asm-generic/vmlinux.lds.h | 7 ++++++- kernel/trace/ftrace.c | 23 ++++++++++------------- 2 files changed, 16 insertions(+), 14 deletions(-) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index db600ef218d7..120babd9ba44 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -145,13 +145,18 @@ * Need to also make ftrace_stub_graph point to ftrace_stub * so that the same stub location may have different protocols * and not mess up with C verifiers. + * + * ftrace_ops_list_func will be defined as arch_ftrace_ops_list_func + * as some archs will have a different prototype for that function + * but ftrace_ops_list_func() will have a single prototype. */ #define MCOUNT_REC() . = ALIGN(8); \ __start_mcount_loc = .; \ KEEP(*(__mcount_loc)) \ KEEP(*(__patchable_function_entries)) \ __stop_mcount_loc = .; \ - ftrace_stub_graph = ftrace_stub; + ftrace_stub_graph = ftrace_stub; \ + ftrace_ops_list_func = arch_ftrace_ops_list_func; #else # ifdef CONFIG_FUNCTION_TRACER # define MCOUNT_REC() ftrace_stub_graph = ftrace_stub; diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index f060838e9cbb..b775d399026e 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -119,14 +119,9 @@ struct ftrace_ops __rcu *ftrace_ops_list __read_mostly = &ftrace_list_end; ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub; struct ftrace_ops global_ops; -#if ARCH_SUPPORTS_FTRACE_OPS -static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip, - struct ftrace_ops *op, struct pt_regs *regs); -#else -/* See comment below, where ftrace_ops_list_func is defined */ -static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip); -#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops) -#endif +/* Defined by vmlinux.lds.h see the commment above arch_ftrace_ops_list_func for details */ +void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *op, struct pt_regs *regs); static inline void ftrace_ops_init(struct ftrace_ops *ops) { @@ -6859,21 +6854,23 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip, * Note, CONFIG_DYNAMIC_FTRACE_WITH_REGS expects a full regs to be saved. * An architecture can pass partial regs with ftrace_ops and still * set the ARCH_SUPPORTS_FTRACE_OPS. + * + * In vmlinux.lds.h, ftrace_ops_list_func() is defined to be + * arch_ftrace_ops_list_func. */ #if ARCH_SUPPORTS_FTRACE_OPS -static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip, - struct ftrace_ops *op, struct pt_regs *regs) +void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *op, struct pt_regs *regs) { __ftrace_ops_list_func(ip, parent_ip, NULL, regs); } -NOKPROBE_SYMBOL(ftrace_ops_list_func); #else -static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip) +void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip) { __ftrace_ops_list_func(ip, parent_ip, NULL, NULL); } -NOKPROBE_SYMBOL(ftrace_ops_no_ops); #endif +NOKPROBE_SYMBOL(arch_ftrace_ops_list_func); /* * If there's only one function registered but it does not support -- 2.25.4
