From 87051ec120bb9abd9e57aecf2569c00d587b6f33 Mon Sep 17 00:00:00 2001 From: Marcin Nowakowski Date: Tue, 23 May 2017 12:56:43 +0200 Subject: MIPS: ftrace: fix init functions tracing Since introduction of tracing for init functions the in_kernel_space() check is no longer correct, as it ignores the init sections. As a result, when probes are inserted (and disabled) in the init functions, a branch instruction is inserted instead of a nop, which is likely to result in random crashes during boot. Remove the MIPS-specific in_kernel_space() method and replace it with a generic core_kernel_text() that also checks for init sections during system boot stage. Fixes: 42c269c88dc1 ("ftrace: Allow for function tracing to record init functions on boot up") Signed-off-by: Marcin Nowakowski Tested-by: Matt Redfearn Cc: Steven Rostedt Cc: Ingo Molnar Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/16092/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/ftrace.c | 24 +++++------------------- 1 file changed, 5 insertions(+), 19 deletions(-) (limited to 'arch') diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c index 30a3b75e88eb..9d9b8fbae202 100644 --- a/arch/mips/kernel/ftrace.c +++ b/arch/mips/kernel/ftrace.c @@ -38,20 +38,6 @@ void arch_ftrace_update_code(int command) #endif -/* - * Check if the address is in kernel space - * - * Clone core_kernel_text() from kernel/extable.c, but doesn't call - * init_kernel_text() for Ftrace doesn't trace functions in init sections. - */ -static inline int in_kernel_space(unsigned long ip) -{ - if (ip >= (unsigned long)_stext && - ip <= (unsigned long)_etext) - return 1; - return 0; -} - #ifdef CONFIG_DYNAMIC_FTRACE #define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */ @@ -198,7 +184,7 @@ int ftrace_make_nop(struct module *mod, * If ip is in kernel space, no long call, otherwise, long call is * needed. */ - new = in_kernel_space(ip) ? INSN_NOP : INSN_B_1F; + new = core_kernel_text(ip) ? INSN_NOP : INSN_B_1F; #ifdef CONFIG_64BIT return ftrace_modify_code(ip, new); #else @@ -218,12 +204,12 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) unsigned int new; unsigned long ip = rec->ip; - new = in_kernel_space(ip) ? insn_jal_ftrace_caller : insn_la_mcount[0]; + new = core_kernel_text(ip) ? insn_jal_ftrace_caller : insn_la_mcount[0]; #ifdef CONFIG_64BIT return ftrace_modify_code(ip, new); #else - return ftrace_modify_code_2r(ip, new, in_kernel_space(ip) ? + return ftrace_modify_code_2r(ip, new, core_kernel_text(ip) ? INSN_NOP : insn_la_mcount[1]); #endif } @@ -289,7 +275,7 @@ unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long * instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for * kernel, move after the instruction "move ra, at"(offset is 16) */ - ip = self_ra - (in_kernel_space(self_ra) ? 16 : 24); + ip = self_ra - (core_kernel_text(self_ra) ? 16 : 24); /* * search the text until finding the non-store instruction or "s{d,w} @@ -394,7 +380,7 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra, * entries configured through the tracing/set_graph_function interface. */ - insns = in_kernel_space(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1; + insns = core_kernel_text(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1; trace.func = self_ra - (MCOUNT_INSN_SIZE * insns); /* Only trace if the calling function expects to */ -- cgit