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[59.124.168.89]) by smtp.gmail.com with ESMTPSA id q1-20020a17090311c100b001cfc9c926b7sm6134629plh.75.2023.12.05.01.00.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Dec 2023 01:00:04 -0800 (PST) From: Zong Li To: palmer@dabbelt.com, paul.walmsley@sifive.com, aou@eecs.berkeley.edu, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Zong Li Subject: [PATCH] riscv: add CALLER_ADDRx support Date: Tue, 5 Dec 2023 08:59:59 +0000 Message-Id: <20231205085959.32177-1-zong.li@sifive.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" CALLER_ADDRx returns caller's address at specified level, they are used for several tracers. These macros eventually use __builtin_return_address(n) to get the caller's address if arch doesn't define their own implementation. In RISC-V, __builtin_return_address(n) only works when n =3D=3D 0, we need to walk the stack frame to get the caller's address at specified level. data.level started from 'level + 3' due to the call flow of getting caller's address in RISC-V implementation. If we don't have additional three iteration, the level is corresponding to follows: callsite -> return_address -> arch_stack_walk -> walk_stackframe | | | | level 3 level 2 level 1 level 0 Signed-off-by: Zong Li Reviewed-by: Alexandre Ghiti --- arch/riscv/include/asm/ftrace.h | 5 ++++ arch/riscv/kernel/Makefile | 2 ++ arch/riscv/kernel/return_address.c | 48 ++++++++++++++++++++++++++++++ 3 files changed, 55 insertions(+) create mode 100644 arch/riscv/kernel/return_address.c diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrac= e.h index 2b2f5df7ef2c..42777f91a9c5 100644 --- a/arch/riscv/include/asm/ftrace.h +++ b/arch/riscv/include/asm/ftrace.h @@ -25,6 +25,11 @@ =20 #define ARCH_SUPPORTS_FTRACE_OPS 1 #ifndef __ASSEMBLY__ + +extern void *return_address(unsigned int level); + +#define ftrace_return_address(n) return_address(n) + void MCOUNT_NAME(void); static inline unsigned long ftrace_call_adjust(unsigned long addr) { diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index fee22a3d1b53..40d054939ae2 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -7,6 +7,7 @@ ifdef CONFIG_FTRACE CFLAGS_REMOVE_ftrace.o =3D $(CC_FLAGS_FTRACE) CFLAGS_REMOVE_patch.o =3D $(CC_FLAGS_FTRACE) CFLAGS_REMOVE_sbi.o =3D $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_return_address.o =3D $(CC_FLAGS_FTRACE) endif CFLAGS_syscall_table.o +=3D $(call cc-option,-Wno-override-init,) CFLAGS_compat_syscall_table.o +=3D $(call cc-option,-Wno-override-init,) @@ -46,6 +47,7 @@ obj-y +=3D irq.o obj-y +=3D process.o obj-y +=3D ptrace.o obj-y +=3D reset.o +obj-y +=3D return_address.o obj-y +=3D setup.o obj-y +=3D signal.o obj-y +=3D syscall_table.o diff --git a/arch/riscv/kernel/return_address.c b/arch/riscv/kernel/return_= address.c new file mode 100644 index 000000000000..c2008d4aa6e5 --- /dev/null +++ b/arch/riscv/kernel/return_address.c @@ -0,0 +1,48 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * This code come from arch/arm64/kernel/return_address.c + * + * Copyright (C) 2023 SiFive. + */ + +#include +#include +#include + +struct return_address_data { + unsigned int level; + void *addr; +}; + +static bool save_return_addr(void *d, unsigned long pc) +{ + struct return_address_data *data =3D d; + + if (!data->level) { + data->addr =3D (void *)pc; + return false; + } + + --data->level; + + return true; +} +NOKPROBE_SYMBOL(save_return_addr); + +void *return_address(unsigned int level) +{ + struct return_address_data data; + + data.level =3D level + 3; + data.addr =3D NULL; + + arch_stack_walk(save_return_addr, &data, current, NULL); + + if (!data.level) + return data.addr; + else + return NULL; + +} +EXPORT_SYMBOL_GPL(return_address); +NOKPROBE_SYMBOL(return_address); --=20 2.17.1