From 5f7fb89a115d53b4a10bf7ba2733e78df281e98d Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Date: Mon, 10 Jun 2024 23:09:36 -0400
Subject: [PATCH] function_graph: Everyone uses
HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, remove it
All architectures that implement function graph also implements
HAVE_FUNCTION_GRAPH_RET_ADDR_PTR. Remove it, as it is no longer a
differentiator.
Link: https://lore.kernel.org/linux-trace-kernel/20240611031737.982047614@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
Documentation/trace/ftrace-design.rst | 12 ---------
arch/arm64/include/asm/ftrace.h | 11 ---------
arch/csky/include/asm/ftrace.h | 2 --
arch/loongarch/include/asm/ftrace.h | 1 -
arch/powerpc/include/asm/ftrace.h | 2 --
arch/riscv/include/asm/ftrace.h | 1 -
arch/s390/include/asm/ftrace.h | 1 -
arch/x86/include/asm/ftrace.h | 2 --
include/linux/ftrace.h | 2 --
kernel/trace/fgraph.c | 35 +--------------------------
10 files changed, 1 insertion(+), 68 deletions(-)
diff --git a/Documentation/trace/ftrace-design.rst b/Documentation/trace/ftrace-design.rst
index 6893399157f0b..dc82d64b3a44b 100644
--- a/Documentation/trace/ftrace-design.rst
+++ b/Documentation/trace/ftrace-design.rst
@@ -217,18 +217,6 @@ along to ftrace_push_return_trace() instead of a stub value of 0.
Similarly, when you call ftrace_return_to_handler(), pass it the frame pointer.
-HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
---------------------------------
-
-An arch may pass in a pointer to the return address on the stack. This
-prevents potential stack unwinding issues where the unwinder gets out of
-sync with ret_stack and the wrong addresses are reported by
-ftrace_graph_ret_addr().
-
-Adding support for it is easy: just define the macro in asm/ftrace.h and
-pass the return address pointer as the 'retp' argument to
-ftrace_push_return_trace().
-
HAVE_SYSCALL_TRACEPOINTS
------------------------
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index ab158196480c3..dc9cf0bd2a4cb 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -12,17 +12,6 @@
#define HAVE_FUNCTION_GRAPH_FP_TEST
-/*
- * HAVE_FUNCTION_GRAPH_RET_ADDR_PTR means that the architecture can provide a
- * "return address pointer" which can be used to uniquely identify a return
- * address which has been overwritten.
- *
- * On arm64 we use the address of the caller's frame record, which remains the
- * same for the lifetime of the instrumented function, unlike the return
- * address in the LR.
- */
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
-
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
#define ARCH_SUPPORTS_FTRACE_OPS 1
#else
diff --git a/arch/csky/include/asm/ftrace.h b/arch/csky/include/asm/ftrace.h
index fd215c38ef277..00f9f7647e3f3 100644
--- a/arch/csky/include/asm/ftrace.h
+++ b/arch/csky/include/asm/ftrace.h
@@ -7,8 +7,6 @@
#define HAVE_FUNCTION_GRAPH_FP_TEST
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
-
#define ARCH_SUPPORTS_FTRACE_OPS 1
#define MCOUNT_ADDR ((unsigned long)_mcount)
diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
index de891c2c83d4a..c0a682808e070 100644
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -28,7 +28,6 @@ struct dyn_ftrace;
struct dyn_arch_ftrace { };
#define ARCH_SUPPORTS_FTRACE_OPS 1
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
#define ftrace_init_nop ftrace_init_nop
int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index 107fc5a484569..559560286e6d0 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -8,8 +8,6 @@
#define MCOUNT_ADDR ((unsigned long)(_mcount))
#define MCOUNT_INSN_SIZE 4 /* sizeof mcount call */
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
-
/* Ignore unused weak functions which will have larger offsets */
#if defined(CONFIG_MPROFILE_KERNEL) || defined(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)
#define FTRACE_MCOUNT_MAX_OFFSET 16
diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index 9eb31a7ea0aa8..2cddd79ff21b1 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -11,7 +11,6 @@
#if defined(CONFIG_FUNCTION_GRAPH_TRACER) && defined(CONFIG_FRAME_POINTER)
#define HAVE_FUNCTION_GRAPH_FP_TEST
#endif
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
#define ARCH_SUPPORTS_FTRACE_OPS 1
#ifndef __ASSEMBLY__
diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h
index 77e479d44f1e3..fbadca645af79 100644
--- a/arch/s390/include/asm/ftrace.h
+++ b/arch/s390/include/asm/ftrace.h
@@ -2,7 +2,6 @@
#ifndef _ASM_S390_FTRACE_H
#define _ASM_S390_FTRACE_H
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
#define ARCH_SUPPORTS_FTRACE_OPS 1
#define MCOUNT_INSN_SIZE 6
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 897cf02c20b1b..0152a81d9b4a2 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -20,8 +20,6 @@
#define ARCH_SUPPORTS_FTRACE_OPS 1
#endif
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
-
#ifndef __ASSEMBLY__
extern void __fentry__(void);
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 4135dc171447a..845c2ab0bc1c9 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1071,9 +1071,7 @@ struct ftrace_ret_stack {
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
unsigned long fp;
#endif
-#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
unsigned long *retp;
-#endif
};
/*
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 91f1eef256af8..8317d1a7f43a7 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -593,9 +593,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
ret_stack->fp = frame_pointer;
#endif
-#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
ret_stack->retp = retp;
-#endif
return offset;
}
@@ -887,10 +885,8 @@ ftrace_graph_get_ret_stack(struct task_struct *task, int idx)
* will be assigned that location so that if called again, it will continue
* where it left off.
*
- * @retp is a pointer to the return address on the stack. It's ignored if
- * the arch doesn't have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR defined.
+ * @retp is a pointer to the return address on the stack.
*/
-#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
unsigned long ret, unsigned long *retp)
{
@@ -926,35 +922,6 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
return ret;
}
-#else /* !HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
-unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
- unsigned long ret, unsigned long *retp)
-{
- struct ftrace_ret_stack *ret_stack;
- unsigned long return_handler = (unsigned long)dereference_kernel_function_descriptor(return_to_handler);
- int offset = task->curr_ret_stack;
- int i;
-
- if (ret != return_handler)
- return ret;
-
- if (!idx)
- return ret;
-
- i = *idx;
- do {
- ret_stack = get_ret_stack(task, offset, &offset);
- if (ret_stack && ret_stack->ret == return_handler)
- continue;
- i--;
- } while (i >= 0 && ret_stack);
-
- if (ret_stack)
- return ret_stack->ret;
-
- return ret;
-}
-#endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
static struct ftrace_ops graph_ops = {
.func = ftrace_graph_func,
--
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