From: Naveen N Rao <naveen@kernel.org>
To: <linuxppc-dev@lists.ozlabs.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH 15/17] powerpc/ftrace: Implement ftrace_replace_code()
Date: Mon, 19 Jun 2023 15:17:33 +0530 [thread overview]
Message-ID: <c28f852225646b0561bbf3c1d22d03f041ace8e0.1687166935.git.naveen@kernel.org> (raw)
In-Reply-To: <cover.1687166935.git.naveen@kernel.org>
Implement ftrace_replace_code() to consolidate logic from the different
ftrace patching routines: ftrace_make_nop(), ftrace_make_call() and
ftrace_modify_call(). Note that ftrace_make_call() is still required
primarily to handle patching modules during their load time. The other
two routines should no longer be called.
This lays the groundwork to enable better control in patching ftrace
locations, including the ability to nop-out preceding profiling
instructions when ftrace is disabled.
Signed-off-by: Naveen N Rao <naveen@kernel.org>
---
arch/powerpc/kernel/trace/ftrace.c | 173 ++++++++++++++++-------------
1 file changed, 96 insertions(+), 77 deletions(-)
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index 422dd760fbe013..cf9dce77527920 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -94,104 +94,123 @@ static unsigned long find_ftrace_tramp(unsigned long ip)
return 0;
}
+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)) {
+ /* 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)) {
+ /* 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 {
+ return -EINVAL;
+ }
+
+ *call_inst = ftrace_create_branch_inst(ip, stub, 1);
+ return 0;
+}
+
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
{
- unsigned long tramp, tramp_old, ip = rec->ip;
- ppc_inst_t old, new;
- struct module *mod;
-
- if (is_offset_in_branch_range(old_addr - ip) && is_offset_in_branch_range(addr - ip)) {
- /* Within range */
- old = ftrace_create_branch_inst(ip, old_addr, 1);
- new = ftrace_create_branch_inst(ip, addr, 1);
- return ftrace_modify_code(ip, old, new);
- } else if (core_kernel_text(ip)) {
- /*
- * We always patch out of range locations to go to the regs
- * variant, so there is nothing to do here
- */
- return 0;
- } else if (IS_ENABLED(CONFIG_MODULES)) {
- /* Module code would be going to one of the module stubs */
- mod = rec->arch.mod;
- if (addr == (unsigned long)ftrace_caller) {
- tramp_old = mod->arch.tramp_regs;
- tramp = mod->arch.tramp;
- } else {
- tramp_old = mod->arch.tramp;
- tramp = mod->arch.tramp_regs;
- }
- old = ftrace_create_branch_inst(ip, tramp_old, 1);
- new = ftrace_create_branch_inst(ip, tramp, 1);
- return ftrace_modify_code(ip, old, new);
- }
-
+ /* This should never be called since we override ftrace_replace_code() */
+ WARN_ON(1);
return -EINVAL;
}
#endif
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
- unsigned long tramp, ip = rec->ip;
ppc_inst_t old, new;
- struct module *mod;
+ int ret;
+
+ /* This can only ever be called during module load */
+ if (WARN_ON(!IS_ENABLED(CONFIG_MODULES) || core_kernel_text(rec->ip)))
+ return -EINVAL;
old = ppc_inst(PPC_RAW_NOP());
- if (is_offset_in_branch_range(addr - ip)) {
- /* Within range */
- new = ftrace_create_branch_inst(ip, addr, 1);
- return ftrace_modify_code(ip, old, new);
- } else if (core_kernel_text(ip)) {
- /* We would be branching to one of our ftrace tramps */
- tramp = find_ftrace_tramp(ip);
- if (!tramp) {
- pr_err("0x%lx: No ftrace trampolines reachable\n", ip);
- return -EINVAL;
- }
- new = ftrace_create_branch_inst(ip, tramp, 1);
- return ftrace_modify_code(ip, old, new);
- } else if (IS_ENABLED(CONFIG_MODULES)) {
- /* Module code would be going to one of the module stubs */
- mod = rec->arch.mod;
- tramp = (addr == (unsigned long)ftrace_caller ? mod->arch.tramp : mod->arch.tramp_regs);
- new = ftrace_create_branch_inst(ip, tramp, 1);
- return ftrace_modify_code(ip, old, new);
- }
+ ret = ftrace_get_call_inst(rec, addr, &new);
+ if (ret)
+ return ret;
- return -EINVAL;
+ return ftrace_modify_code(rec->ip, old, new);
}
int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
{
- unsigned long tramp, ip = rec->ip;
- ppc_inst_t old, new;
+ /*
+ * This should never be called since we override ftrace_replace_code(),
+ * as well as ftrace_init_nop()
+ */
+ WARN_ON(1);
+ return -EINVAL;
+}
- /* Nop-out the ftrace location */
- new = ppc_inst(PPC_RAW_NOP());
- if (is_offset_in_branch_range(addr - ip)) {
- /* Within range */
- old = ftrace_create_branch_inst(ip, addr, 1);
- return ftrace_modify_code(ip, old, new);
- } else if (core_kernel_text(ip)) {
- /* We would be branching to one of our ftrace tramps */
- tramp = find_ftrace_tramp(ip);
- if (!tramp) {
- pr_err("0x%lx: No ftrace trampolines reachable\n", ip);
- return -EINVAL;
+void ftrace_replace_code(int enable)
+{
+ ppc_inst_t old, new, call_inst, new_call_inst;
+ ppc_inst_t nop_inst = ppc_inst(PPC_RAW_NOP());
+ unsigned long ip, new_addr, addr;
+ struct ftrace_rec_iter *iter;
+ struct dyn_ftrace *rec;
+ int ret = 0, update;
+
+ for_ftrace_rec_iter(iter) {
+ rec = ftrace_rec_iter_record(iter);
+ ip = rec->ip;
+
+ if (rec->flags & FTRACE_FL_DISABLED && !(rec->flags & FTRACE_FL_ENABLED))
+ continue;
+
+ addr = ftrace_get_addr_curr(rec);
+ new_addr = ftrace_get_addr_new(rec);
+ update = ftrace_update_record(rec, enable);
+
+ switch (update) {
+ case FTRACE_UPDATE_IGNORE:
+ default:
+ continue;
+ case FTRACE_UPDATE_MODIFY_CALL:
+ ret = ftrace_get_call_inst(rec, new_addr, &new_call_inst);
+ ret |= ftrace_get_call_inst(rec, addr, &call_inst);
+ old = call_inst;
+ new = new_call_inst;
+ break;
+ case FTRACE_UPDATE_MAKE_NOP:
+ ret = ftrace_get_call_inst(rec, addr, &call_inst);
+ old = call_inst;
+ new = nop_inst;
+ break;
+ case FTRACE_UPDATE_MAKE_CALL:
+ ret = ftrace_get_call_inst(rec, new_addr, &call_inst);
+ old = nop_inst;
+ new = call_inst;
+ break;
}
- old = ftrace_create_branch_inst(ip, tramp, 1);
- return ftrace_modify_code(ip, old, new);
- } else if (IS_ENABLED(CONFIG_MODULES)) {
- /* Module code would be going to one of the module stubs */
- if (!mod)
- mod = rec->arch.mod;
- tramp = (addr == (unsigned long)ftrace_caller ? mod->arch.tramp : mod->arch.tramp_regs);
- old = ftrace_create_branch_inst(ip, tramp, 1);
- return ftrace_modify_code(ip, old, new);
+
+ if (!ret)
+ ret = ftrace_modify_code(ip, old, new);
+ if (ret)
+ goto out;
}
- return -EINVAL;
+out:
+ if (ret)
+ ftrace_bug(ret, rec);
+ return;
}
int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
--
2.40.1
next prev parent reply other threads:[~2023-06-19 9:57 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-19 9:47 [PATCH 00/17] powerpc/ftrace: refactor and add support for -fpatchable-function-entry Naveen N Rao
2023-06-19 9:47 ` [PATCH 01/17] powerpc/ftrace: Fix dropping weak symbols with older toolchains Naveen N Rao
2023-06-23 5:10 ` Christophe Leroy
2023-06-19 9:47 ` [PATCH 02/17] powerpc/module: Remove unused .ftrace.tramp section Naveen N Rao
2023-06-23 5:12 ` Christophe Leroy
2023-06-19 9:47 ` [PATCH 03/17] powerpc64/ftrace: Move ELFv1 and -pg support code into a separate file Naveen N Rao
2023-06-23 5:13 ` Christophe Leroy
2023-06-19 9:47 ` [PATCH 04/17] powerpc/ftrace: Simplify function_graph support in ftrace.c Naveen N Rao
2023-06-23 5:14 ` Christophe Leroy
2023-06-19 9:47 ` [PATCH 05/17] powerpc/ftrace: Use FTRACE_REGS_ADDR to identify the correct ftrace trampoline Naveen N Rao
2023-06-23 5:15 ` Christophe Leroy
2023-06-19 9:47 ` [PATCH 06/17] powerpc/ftrace: Extend ftrace support for large kernels to ppc32 Naveen N Rao
2023-06-23 5:21 ` Christophe Leroy
2023-06-19 9:47 ` [PATCH 07/17] powerpc/ftrace: Consolidate ftrace support into fewer files Naveen N Rao
2023-06-23 5:25 ` Christophe Leroy
2023-06-28 7:32 ` Naveen N Rao
2023-06-19 9:47 ` [PATCH 08/17] powerpc/ftrace: Refactor ftrace_modify_code() Naveen N Rao
2023-06-23 5:27 ` Christophe Leroy
2023-06-19 9:47 ` [PATCH 09/17] powerpc/ftrace: Stop re-purposing linker generated long branches for ftrace Naveen N Rao
2023-06-23 5:28 ` Christophe Leroy
2023-06-19 9:47 ` [PATCH 10/17] powerpc/ftrace: Add separate ftrace_init_nop() with additional validation Naveen N Rao
2023-06-23 5:29 ` Christophe Leroy
2023-06-19 9:47 ` [PATCH 11/17] powerpc/ftrace: Simplify ftrace_make_nop() Naveen N Rao
2023-06-23 5:30 ` Christophe Leroy
2023-06-19 9:47 ` [PATCH 12/17] powerpc/ftrace: Simplify ftrace_make_call() Naveen N Rao
2023-06-23 5:30 ` Christophe Leroy
2023-06-19 9:47 ` [PATCH 13/17] powerpc/ftrace: Simplify ftrace_modify_call() Naveen N Rao
2023-06-23 5:31 ` Christophe Leroy
2023-06-19 9:47 ` [PATCH 14/17] powerpc/ftrace: Replace use of ftrace_call_replace() with ftrace_create_branch_inst() Naveen N Rao
2023-06-23 5:32 ` Christophe Leroy
2023-06-19 9:47 ` Naveen N Rao [this message]
2023-06-23 5:32 ` [PATCH 15/17] powerpc/ftrace: Implement ftrace_replace_code() Christophe Leroy
2023-06-19 9:47 ` [PATCH 16/17] powerpc/ftrace: Add support for -fpatchable-function-entry Naveen N Rao
2023-06-23 5:37 ` Christophe Leroy
2023-06-28 7:40 ` Naveen N Rao
2023-06-19 9:47 ` [PATCH 17/17] powerpc/ftrace: Create a dummy stackframe to fix stack unwind Naveen N Rao
2023-06-23 5:40 ` Christophe Leroy
2023-06-28 7:43 ` Naveen N Rao
2023-08-23 11:55 ` [PATCH 00/17] powerpc/ftrace: refactor and add support for -fpatchable-function-entry Michael Ellerman
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