From: Andy Chiu <andy.chiu@sifive.com>
To: linux-riscv@lists.infradead.org, palmer@dabbelt.com,
mingo@redhat.com, paul.walmsley@sifive.com,
aou@eecs.berkeley.edu, rostedt@goodmis.org
Cc: guoren@linux.alibaba.com, Andy Chiu <andy.chiu@sifive.com>,
Greentime Hu <greentime.hu@sifive.com>,
Zong Li <zong.li@sifive.com>
Subject: [RFC PATCH riscv/for-next 1/4] riscv: align ftrace to 4 Byte boundary and increase ftrace prologue size
Date: Sun, 29 May 2022 22:33:12 +0800 [thread overview]
Message-ID: <20220529143315.3678563-2-andy.chiu@sifive.com> (raw)
In-Reply-To: <20220529143315.3678563-1-andy.chiu@sifive.com>
We are introducing a new ftrace mechanism in order to phase out
stop_machine() and enable kernel preemption. The new mechanism requires
ftrace patchable function entries to be 24 bytes and aligned to 4 Byte
boundaries.
Before applying this patch, the size of the kernel code, with 43432 of
ftrace entries, was at 12.31 MB. Under the same configuration, the size
has increased to 12.68 MB after applying this patch set.
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Zong Li <zong.li@sifive.com>
---
arch/riscv/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 1f19bdac6767..cb6cfdffc49c 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -11,7 +11,7 @@ LDFLAGS_vmlinux :=
ifeq ($(CONFIG_DYNAMIC_FTRACE),y)
LDFLAGS_vmlinux := --no-relax
KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
- CC_FLAGS_FTRACE := -fpatchable-function-entry=8
+ CC_FLAGS_FTRACE := -fpatchable-function-entry=12 -falign-functions=4
endif
ifeq ($(CONFIG_CMODEL_MEDLOW),y)
--
2.36.0
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next prev parent reply other threads:[~2022-05-29 14:36 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-29 14:33 [RFC PATCH riscv/for-next 0/4] Enable ftrace with kernel preemption for RISC-V Andy Chiu
2022-05-29 14:33 ` Andy Chiu [this message]
2022-07-21 5:40 ` [RFC PATCH riscv/for-next 1/4] riscv: align ftrace to 4 Byte boundary and increase ftrace prologue size Palmer Dabbelt
2022-05-29 14:33 ` [RFC PATCH riscv/for-next 2/4] riscv: export patch_insn_write Andy Chiu
2022-07-21 5:40 ` Palmer Dabbelt
2022-05-29 14:33 ` [RFC PATCH riscv/for-next 3/4] riscv: ftrace: use indirect jump to work with kernel preemption Andy Chiu
2022-07-21 5:40 ` Palmer Dabbelt
2022-05-29 14:33 ` [RFC PATCH riscv/for-next 4/4] riscv: ftrace: do not use stop_machine to update code Andy Chiu
2022-06-05 16:14 ` Steven Rostedt
2022-07-21 5:40 ` Palmer Dabbelt
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