From patchwork Thu Jun 20 18:54:07 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Naveen N Rao X-Patchwork-Id: 13706255 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 753DB1B4C52; Thu, 20 Jun 2024 18:57:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718909855; cv=none; b=EaCdqNliRxr1vcMs3n5jM0xxTJI4c/5nIk7Fz6vAfBSMqtzcOQ2r0QfVmKUgkX+8sZpc0A9pEpifMyZf8ErvEWZB5A/xZsIUIFdcTtTXpMe9w4l/wUMhhr0hFp5mZDJ5QNc2N+CQZrmwOmU+k9m8D/o7ttrvRqQr4cPjHFh46lE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718909855; c=relaxed/simple; bh=DZdFrUJ5SilEc1M16PoFhBmiPn8mbq45LmzFEajKIbQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OkU/ggI0P7paI3jJ8WUejB/iauoLEUXU2K9pjQRg/qFcw83B/KnOKeP2qYa1QSiUTOg82DWIVsSBECyLypa0D3vvWCqLIkArAb7Kay9BmDBl9qfudBANCvrE+5IegirP6e9XljZR9X67Moj91a257ZPnkCXunFfNxXr8MWo2N+8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hgkRbjdK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hgkRbjdK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 302C0C2BD10; Thu, 20 Jun 2024 18:57:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1718909854; bh=DZdFrUJ5SilEc1M16PoFhBmiPn8mbq45LmzFEajKIbQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hgkRbjdK0SVOxK230WkJejN50WJA7kNFQjrAUfrhuH0kA88w/flluJ0UD6HlcpJMu 3Jte65/U8gkMYVuJCHg0mcQ8w0HCJbD5gx2zHzSEHXHkzcOqH1JY8S5Z0YFYbNGFT9 XDBFzLLkXwBVLtnsRSSvEeKInPq+79zrAkoLR59Xh/E3n/zRJkpuiFZ58XXK5/LEjG zsnWlIbl71rQy0NXEWf5yOKr+KeWxx8IS/qHcTihM8DGfIvXWBK97KoTsJ2V0hBdgu MJyIOVL27n2G+dBTp3/mIFlwB9FL9Q2HMnEImYj6Ht9YMfxcW80AHwjnMyGiaQjA4x 4kT5cKZD2QzrA== From: Naveen N Rao To: , , Cc: Michael Ellerman , Steven Rostedt , Masami Hiramatsu , Nicholas Piggin , Christophe Leroy , Masahiro Yamada , Mark Rutland , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Song Liu , Jiri Olsa Subject: [RFC PATCH v3 04/11] powerpc/ftrace: Remove pointer to struct module from dyn_arch_ftrace Date: Fri, 21 Jun 2024 00:24:07 +0530 Message-ID: X-Mailer: git-send-email 2.45.2 In-Reply-To: References: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-State: RFC Pointer to struct module is only relevant for ftrace records belonging to kernel modules. Having this field in dyn_arch_ftrace wastes memory for all ftrace records belonging to the kernel. Remove the same in favour of looking up the module from the ftrace record address, similar to other architectures. Signed-off-by: Naveen N Rao Reviewed-by: Nicholas Piggin --- arch/powerpc/include/asm/ftrace.h | 1 - arch/powerpc/kernel/trace/ftrace.c | 54 +++++++++++------- arch/powerpc/kernel/trace/ftrace_64_pg.c | 73 +++++++++++------------- 3 files changed, 65 insertions(+), 63 deletions(-) diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index 107fc5a48456..201f9d15430a 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -26,7 +26,6 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip, struct module; struct dyn_ftrace; struct dyn_arch_ftrace { - struct module *mod; }; #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c index 463bd7531dc8..2cff37b5fd2c 100644 --- a/arch/powerpc/kernel/trace/ftrace.c +++ b/arch/powerpc/kernel/trace/ftrace.c @@ -106,28 +106,48 @@ static unsigned long find_ftrace_tramp(unsigned long ip) return 0; } +#ifdef CONFIG_MODULES +static unsigned long ftrace_lookup_module_stub(unsigned long ip, unsigned long addr) +{ + struct module *mod = NULL; + + /* + * NOTE: __module_text_address() must be called with preemption + * disabled, but we can rely on ftrace_lock to ensure that 'mod' + * retains its validity throughout the remainder of this code. + */ + preempt_disable(); + mod = __module_text_address(ip); + preempt_enable(); + + if (!mod) + pr_err("No module loaded at addr=%lx\n", ip); + + return (addr == (unsigned long)ftrace_caller ? mod->arch.tramp : mod->arch.tramp_regs); +} +#else +static unsigned long ftrace_lookup_module_stub(unsigned long ip, unsigned long addr) +{ + return 0; +} +#endif + static int ftrace_get_call_inst(struct dyn_ftrace *rec, unsigned long addr, ppc_inst_t *call_inst) { unsigned long ip = rec->ip; unsigned long stub; - if (is_offset_in_branch_range(addr - ip)) { + if (is_offset_in_branch_range(addr - ip)) /* Within range */ stub = addr; -#ifdef CONFIG_MODULES - } else if (rec->arch.mod) { - /* Module code would be going to one of the module stubs */ - stub = (addr == (unsigned long)ftrace_caller ? rec->arch.mod->arch.tramp : - rec->arch.mod->arch.tramp_regs); -#endif - } else if (core_kernel_text(ip)) { + else if (core_kernel_text(ip)) /* We would be branching to one of our ftrace stubs */ stub = find_ftrace_tramp(ip); - if (!stub) { - pr_err("0x%lx: No ftrace stubs reachable\n", ip); - return -EINVAL; - } - } else { + else + stub = ftrace_lookup_module_stub(ip, addr); + + if (!stub) { + pr_err("0x%lx: No ftrace stubs reachable\n", ip); return -EINVAL; } @@ -258,14 +278,6 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) if (ret) return ret; - if (!core_kernel_text(ip)) { - if (!mod) { - pr_err("0x%lx: No module provided for non-kernel address\n", ip); - return -EFAULT; - } - rec->arch.mod = mod; - } - /* Nop-out the ftrace location */ new = ppc_inst(PPC_RAW_NOP()); addr = MCOUNT_ADDR; diff --git a/arch/powerpc/kernel/trace/ftrace_64_pg.c b/arch/powerpc/kernel/trace/ftrace_64_pg.c index 12fab1803bcf..a563b9ffcc2b 100644 --- a/arch/powerpc/kernel/trace/ftrace_64_pg.c +++ b/arch/powerpc/kernel/trace/ftrace_64_pg.c @@ -116,6 +116,24 @@ static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op) } #ifdef CONFIG_MODULES +static struct module *ftrace_lookup_module(struct dyn_ftrace *rec) +{ + struct module *mod; + /* + * NOTE: __module_text_address() must be called with preemption + * disabled, but we can rely on ftrace_lock to ensure that 'mod' + * retains its validity throughout the remainder of this code. + */ + preempt_disable(); + mod = __module_text_address(rec->ip); + preempt_enable(); + + if (!mod) + pr_err("No module loaded at addr=%lx\n", rec->ip); + + return mod; +} + static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) @@ -124,6 +142,12 @@ __ftrace_make_nop(struct module *mod, unsigned long ip = rec->ip; ppc_inst_t op, pop; + if (!mod) { + mod = ftrace_lookup_module(rec); + if (!mod) + return -EINVAL; + } + /* read where this goes */ if (copy_inst_from_kernel_nofault(&op, (void *)ip)) { pr_err("Fetching opcode failed.\n"); @@ -366,27 +390,6 @@ int ftrace_make_nop(struct module *mod, return -EINVAL; } - /* - * Out of range jumps are called from modules. - * We should either already have a pointer to the module - * or it has been passed in. - */ - if (!rec->arch.mod) { - if (!mod) { - pr_err("No module loaded addr=%lx\n", addr); - return -EFAULT; - } - rec->arch.mod = mod; - } else if (mod) { - if (mod != rec->arch.mod) { - pr_err("Record mod %p not equal to passed in mod %p\n", - rec->arch.mod, mod); - return -EINVAL; - } - /* nothing to do if mod == rec->arch.mod */ - } else - mod = rec->arch.mod; - return __ftrace_make_nop(mod, rec, addr); } @@ -411,7 +414,10 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) ppc_inst_t op[2]; void *ip = (void *)rec->ip; unsigned long entry, ptr, tramp; - struct module *mod = rec->arch.mod; + struct module *mod = ftrace_lookup_module(rec); + + if (!mod) + return -EINVAL; /* read where this goes */ if (copy_inst_from_kernel_nofault(op, ip)) @@ -533,16 +539,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) return -EINVAL; } - /* - * Out of range jumps are called from modules. - * Being that we are converting from nop, it had better - * already have a module defined. - */ - if (!rec->arch.mod) { - pr_err("No module loaded\n"); - return -EINVAL; - } - return __ftrace_make_call(rec, addr); } @@ -555,7 +551,10 @@ __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, ppc_inst_t op; unsigned long ip = rec->ip; unsigned long entry, ptr, tramp; - struct module *mod = rec->arch.mod; + struct module *mod = ftrace_lookup_module(rec); + + if (!mod) + return -EINVAL; /* If we never set up ftrace trampolines, then bail */ if (!mod->arch.tramp || !mod->arch.tramp_regs) { @@ -668,14 +667,6 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, return -EINVAL; } - /* - * Out of range jumps are called from modules. - */ - if (!rec->arch.mod) { - pr_err("No module loaded\n"); - return -EINVAL; - } - return __ftrace_modify_call(rec, old_addr, addr); } #endif