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From:   Christophe Leroy <christophe.leroy@csgroup.eu>
To:     "Naveen N . Rao" <naveen.n.rao@linux.vnet.ibm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>
Cc:     Christophe Leroy <christophe.leroy@csgroup.eu>,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v1 08/22] powerpc/ftrace: Make __ftrace_make_{nop/call}() common to PPC32 and PPC64
Date:   Thu, 24 Mar 2022 15:29:58 +0100
Message-Id: <fb60b19f154db8132a00c2df7aca7db3e85603b5.1648131740.git.christophe.leroy@csgroup.eu>
In-Reply-To: <cover.1648131740.git.christophe.leroy@csgroup.eu>
References: <cover.1648131740.git.christophe.leroy@csgroup.eu>
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Since c93d4f6ecf4b ("powerpc/ftrace: Add module_trampoline_target()
for PPC32"), __ftrace_make_nop() for PPC32 is very similar to the
one for PPC64.

Same for __ftrace_make_call().

Make them common.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/kernel/trace/ftrace.c | 108 +++--------------------------
 1 file changed, 8 insertions(+), 100 deletions(-)

diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index 1b05d33f96c6..2c7e42e439bb 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -114,7 +114,6 @@ static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op)
 }
 
 #ifdef CONFIG_MODULES
-#ifdef CONFIG_PPC64
 static int
 __ftrace_make_nop(struct module *mod,
 		  struct dyn_ftrace *rec, unsigned long addr)
@@ -154,10 +153,11 @@ __ftrace_make_nop(struct module *mod,
 		return -EINVAL;
 	}
 
-#ifdef CONFIG_MPROFILE_KERNEL
-	/* When using -mkernel_profile there is no load to jump over */
+	/* When using -mkernel_profile or PPC32 there is no load to jump over */
 	pop = ppc_inst(PPC_RAW_NOP());
 
+#ifdef CONFIG_PPC64
+#ifdef CONFIG_MPROFILE_KERNEL
 	if (copy_inst_from_kernel_nofault(&op, (void *)(ip - 4))) {
 		pr_err("Fetching instruction at %lx failed.\n", ip - 4);
 		return -EFAULT;
@@ -201,6 +201,7 @@ __ftrace_make_nop(struct module *mod,
 		return -EINVAL;
 	}
 #endif /* CONFIG_MPROFILE_KERNEL */
+#endif /* PPC64 */
 
 	if (patch_instruction((u32 *)ip, pop)) {
 		pr_err("Patching NOP failed.\n");
@@ -209,48 +210,6 @@ __ftrace_make_nop(struct module *mod,
 
 	return 0;
 }
-
-#else /* !PPC64 */
-static int
-__ftrace_make_nop(struct module *mod,
-		  struct dyn_ftrace *rec, unsigned long addr)
-{
-	ppc_inst_t op;
-	unsigned long ip = rec->ip;
-	unsigned long tramp, ptr;
-
-	if (copy_from_kernel_nofault(&op, (void *)ip, MCOUNT_INSN_SIZE))
-		return -EFAULT;
-
-	/* Make sure that that this is still a 24bit jump */
-	if (!is_bl_op(op)) {
-		pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
-		return -EINVAL;
-	}
-
-	/* lets find where the pointer goes */
-	tramp = find_bl_target(ip, op);
-
-	/* Find where the trampoline jumps to */
-	if (module_trampoline_target(mod, tramp, &ptr)) {
-		pr_err("Failed to get trampoline target\n");
-		return -EFAULT;
-	}
-
-	if (ptr != addr) {
-		pr_err("Trampoline location %08lx does not match addr\n",
-		       tramp);
-		return -EINVAL;
-	}
-
-	op = ppc_inst(PPC_RAW_NOP());
-
-	if (patch_instruction((u32 *)ip, op))
-		return -EPERM;
-
-	return 0;
-}
-#endif /* PPC64 */
 #endif /* CONFIG_MODULES */
 
 static unsigned long find_ftrace_tramp(unsigned long ip)
@@ -437,13 +396,12 @@ int ftrace_make_nop(struct module *mod,
 }
 
 #ifdef CONFIG_MODULES
-#ifdef CONFIG_PPC64
 /*
  * Examine the existing instructions for __ftrace_make_call.
  * They should effectively be a NOP, and follow formal constraints,
  * depending on the ABI. Return false if they don't.
  */
-#ifndef CONFIG_MPROFILE_KERNEL
+#ifndef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 static int
 expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1)
 {
@@ -465,7 +423,7 @@ expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1)
 static int
 expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1)
 {
-	/* look for patched "NOP" on ppc64 with -mprofile-kernel */
+	/* look for patched "NOP" on ppc64 with -mprofile-kernel or ppc32 */
 	if (!ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP())))
 		return 0;
 	return 1;
@@ -484,8 +442,10 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 	if (copy_inst_from_kernel_nofault(op, ip))
 		return -EFAULT;
 
+#ifndef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 	if (copy_inst_from_kernel_nofault(op + 1, ip + 4))
 		return -EFAULT;
+#endif
 
 	if (!expected_nop_sequence(ip, op[0], op[1])) {
 		pr_err("Unexpected call sequence at %p: %s %s\n",
@@ -531,58 +491,6 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 
 	return 0;
 }
-
-#else  /* !CONFIG_PPC64: */
-static int
-__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
-{
-	int err;
-	ppc_inst_t op;
-	u32 *ip = (u32 *)rec->ip;
-	struct module *mod = rec->arch.mod;
-	unsigned long tramp;
-
-	/* read where this goes */
-	if (copy_inst_from_kernel_nofault(&op, ip))
-		return -EFAULT;
-
-	/* It should be pointing to a nop */
-	if (!ppc_inst_equal(op,  ppc_inst(PPC_RAW_NOP()))) {
-		pr_err("Expected NOP but have %s\n", ppc_inst_as_str(op));
-		return -EINVAL;
-	}
-
-	/* If we never set up a trampoline to ftrace_caller, then bail */
-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
-	if (!mod->arch.tramp || !mod->arch.tramp_regs) {
-#else
-	if (!mod->arch.tramp) {
-#endif
-		pr_err("No ftrace trampoline\n");
-		return -EINVAL;
-	}
-
-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
-	if (rec->flags & FTRACE_FL_REGS)
-		tramp = mod->arch.tramp_regs;
-	else
-#endif
-		tramp = mod->arch.tramp;
-	/* create the branch to the trampoline */
-	err = create_branch(&op, ip, tramp, BRANCH_SET_LINK);
-	if (err) {
-		pr_err("REL24 out of range!\n");
-		return -EINVAL;
-	}
-
-	pr_devel("write to %lx\n", rec->ip);
-
-	if (patch_instruction(ip, op))
-		return -EPERM;
-
-	return 0;
-}
-#endif /* CONFIG_PPC64 */
 #endif /* CONFIG_MODULES */
 
 static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
-- 
2.35.1