From: Naveen N Rao <naveen@kernel.org>
To: <linuxppc-dev@lists.ozlabs.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH 08/17] powerpc/ftrace: Refactor ftrace_modify_code()
Date: Mon, 19 Jun 2023 15:17:26 +0530 [thread overview]
Message-ID: <a8daa49712b44ff539e6c22a2ea649a540386798.1687166935.git.naveen@kernel.org> (raw)
In-Reply-To: <cover.1687166935.git.naveen@kernel.org>
Split up ftrace_modify_code() into a few helpers for future use. Also
update error messages accordingly.
Signed-off-by: Naveen N Rao <naveen@kernel.org>
---
arch/powerpc/kernel/trace/ftrace.c | 51 +++++++++++++++++-------------
1 file changed, 29 insertions(+), 22 deletions(-)
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index 913c7aa63d3fa3..ef4e49c2c37781 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -50,32 +50,39 @@ ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
return op;
}
-static inline int
-ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
+static inline int ftrace_read_inst(unsigned long ip, ppc_inst_t *op)
{
- ppc_inst_t replaced;
-
- /*
- * Note:
- * We are paranoid about modifying text, as if a bug was to happen, it
- * could cause us to read or write to someplace that could cause harm.
- * Carefully read and modify the code with probe_kernel_*(), and make
- * sure what we read is what we expected it to be before modifying it.
- */
-
- /* read the text we want to modify */
- if (copy_inst_from_kernel_nofault(&replaced, (void *)ip))
+ if (copy_inst_from_kernel_nofault(op, (void *)ip)) {
+ pr_err("0x%lx: fetching instruction failed\n", ip);
return -EFAULT;
-
- /* Make sure it is what we expect it to be */
- if (!ppc_inst_equal(replaced, old)) {
- pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip,
- ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old));
- return -EINVAL;
}
- /* replace the text with the new text */
- return patch_instruction((u32 *)ip, new);
+ return 0;
+}
+
+static inline int ftrace_validate_inst(unsigned long ip, ppc_inst_t inst)
+{
+ ppc_inst_t op;
+ int ret;
+
+ ret = ftrace_read_inst(ip, &op);
+ if (!ret && !ppc_inst_equal(op, inst)) {
+ pr_err("0x%lx: expected (%08lx) != found (%08lx)\n",
+ ip, ppc_inst_as_ulong(inst), ppc_inst_as_ulong(op));
+ ret = -EINVAL;
+ }
+
+ return ret;
+}
+
+static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
+{
+ int ret = ftrace_validate_inst(ip, old);
+
+ if (!ret)
+ ret = patch_instruction((u32 *)ip, new);
+
+ return ret;
}
/*
--
2.40.1
next prev parent reply other threads:[~2023-06-19 10:02 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 ` Naveen N Rao [this message]
2023-06-23 5:27 ` [PATCH 08/17] powerpc/ftrace: Refactor ftrace_modify_code() 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 ` [PATCH 15/17] powerpc/ftrace: Implement ftrace_replace_code() Naveen N Rao
2023-06-23 5:32 ` 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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