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[133.18.108.210]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-32b747c2d66sm3510656a91.28.2025.09.04.03.01.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Sep 2025 03:01:29 -0700 (PDT) From: ChenMiao To: Linux Kernel , Linux OpenRISC Cc: chenmiao , Jonas Bonn , Stefan Kristiansson , Stafford Horne , Geert Uytterhoeven , Andrew Morton , "Mike Rapoport (Microsoft)" , Luis Chamberlain , Johannes Berg , Nicolas Schier , Sahil Siddiq , Masahiro Yamada , Dave Hansen Subject: [PATCH v4 1/4] openrisc: Add text patching API support Date: Thu, 4 Sep 2025 10:00:49 +0000 Message-ID: <20250904100109.688033-2-chenmiao.ku@gmail.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20250904100109.688033-1-chenmiao.ku@gmail.com> References: <20250904100109.688033-1-chenmiao.ku@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: chenmiao Add text patching api's to use in subsequent jump_label implementation. We= use a new fixmap FIX_TEXT_POKE0 entry to temporarily override MMU mappings to a= llow read only text pages to be written to. Previously, __set_fix was marked with __init as it was only used during the EARLYCON stage. Now that TEXT_POKE mappings require post-init usage (e.g., FIX_TEXT_POKE0), keeping __init would cause runtime bugs whenset_fix= map accesses invalid memory. Thus, we remove the __init flag to ensure __set_fix remains valid beyond initialization. A new function patch_insn_write is exposed to allow single instruction patc= hing. Link: https://lore.kernel.org/openrisc/aJIC8o1WmVHol9RY@antec/T/#t Signed-off-by: chenmiao --- Changes in V4: - Fixed incorrect macro definitions and malformed comments. Changes in V3: - Removed the unimplemented and unsupported is_exit_text, added comments for the set_fixmap modification explaining why __init was removed, and added new comments for patch_insn_write. Changes in V2: - We modify the patch_insn_write(void *addr, const void *insn) API to patch_insn_write(void *addr, u32 insn), derectly support a single u32 instruction write to map memory. - Create a new file named insn-def.h to define the or1k insn macro size and more define in the future. Signed-off-by: chenmiao --- arch/openrisc/include/asm/Kbuild | 1 - arch/openrisc/include/asm/fixmap.h | 1 + arch/openrisc/include/asm/insn-def.h | 12 ++++ arch/openrisc/include/asm/text-patching.h | 13 ++++ arch/openrisc/kernel/Makefile | 1 + arch/openrisc/kernel/patching.c | 79 +++++++++++++++++++++++ arch/openrisc/mm/init.c | 6 +- 7 files changed, 111 insertions(+), 2 deletions(-) create mode 100644 arch/openrisc/include/asm/insn-def.h create mode 100644 arch/openrisc/include/asm/text-patching.h create mode 100644 arch/openrisc/kernel/patching.c diff --git a/arch/openrisc/include/asm/Kbuild b/arch/openrisc/include/asm/K= build index 2b1a6b00cdac..cef49d60d74c 100644 --- a/arch/openrisc/include/asm/Kbuild +++ b/arch/openrisc/include/asm/Kbuild @@ -9,4 +9,3 @@ generic-y +=3D spinlock.h generic-y +=3D qrwlock_types.h generic-y +=3D qrwlock.h generic-y +=3D user.h -generic-y +=3D text-patching.h diff --git a/arch/openrisc/include/asm/fixmap.h b/arch/openrisc/include/asm= /fixmap.h index aaa6a26a3e92..74000215064d 100644 --- a/arch/openrisc/include/asm/fixmap.h +++ b/arch/openrisc/include/asm/fixmap.h @@ -28,6 +28,7 @@ =20 enum fixed_addresses { FIX_EARLYCON_MEM_BASE, + FIX_TEXT_POKE0, __end_of_fixed_addresses }; =20 diff --git a/arch/openrisc/include/asm/insn-def.h b/arch/openrisc/include/a= sm/insn-def.h new file mode 100644 index 000000000000..e28a9a9604fc --- /dev/null +++ b/arch/openrisc/include/asm/insn-def.h @@ -0,0 +1,12 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2025 Chen Miao + */ + +#ifndef __ASM_OPENRISC_INSN_DEF_H +#define __ASM_OPENRISC_INSN_DEF_H + +/* or1k instructions are always 32 bits. */ +#define OPENRISC_INSN_SIZE 4 + +#endif /* __ASM_OPENRISC_INSN_DEF_H */ diff --git a/arch/openrisc/include/asm/text-patching.h b/arch/openrisc/incl= ude/asm/text-patching.h new file mode 100644 index 000000000000..d19098dac0cc --- /dev/null +++ b/arch/openrisc/include/asm/text-patching.h @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2025 Chen Miao + */ + +#ifndef _ASM_OPENRISC_PATCHING_H +#define _ASM_OPENRISC_PATCHING_H + +#include + +int patch_insn_write(void *addr, u32 insn); + +#endif /* _ASM_OPENRISC_PATCHING_H */ diff --git a/arch/openrisc/kernel/Makefile b/arch/openrisc/kernel/Makefile index 58e6a1b525b7..f0957ce16d6b 100644 --- a/arch/openrisc/kernel/Makefile +++ b/arch/openrisc/kernel/Makefile @@ -13,5 +13,6 @@ obj-$(CONFIG_SMP) +=3D smp.o sync-timer.o obj-$(CONFIG_STACKTRACE) +=3D stacktrace.o obj-$(CONFIG_MODULES) +=3D module.o obj-$(CONFIG_OF) +=3D prom.o +obj-y +=3D patching.o =20 clean: diff --git a/arch/openrisc/kernel/patching.c b/arch/openrisc/kernel/patchin= g.c new file mode 100644 index 000000000000..d186172beb33 --- /dev/null +++ b/arch/openrisc/kernel/patching.c @@ -0,0 +1,79 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (C) 2020 SiFive + * Copyright (C) 2025 Chen Miao + */ + +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include + +static DEFINE_RAW_SPINLOCK(patch_lock); + +static __always_inline void *patch_map(void *addr, int fixmap) +{ + uintptr_t uaddr =3D (uintptr_t) addr; + phys_addr_t phys; + + if (core_kernel_text(uaddr)) { + phys =3D __pa_symbol(addr); + } else { + struct page *page =3D vmalloc_to_page(addr); + BUG_ON(!page); + phys =3D page_to_phys(page) + offset_in_page(addr); + } + + return (void *)set_fixmap_offset(fixmap, phys); +} + +static void patch_unmap(int fixmap) +{ + clear_fixmap(fixmap); +} + +static int __patch_insn_write(void *addr, u32 insn) +{ + void *waddr =3D addr; + unsigned long flags =3D 0; + int ret; + + raw_spin_lock_irqsave(&patch_lock, flags); + + waddr =3D patch_map(addr, FIX_TEXT_POKE0); + + ret =3D copy_to_kernel_nofault(waddr, &insn, OPENRISC_INSN_SIZE); + local_icache_range_inv((unsigned long)waddr, + (unsigned long)waddr + OPENRISC_INSN_SIZE); + + patch_unmap(FIX_TEXT_POKE0); + + raw_spin_unlock_irqrestore(&patch_lock, flags); + + return ret; +} + +/* + * patch_insn_write - Write a single instruction to a specified memory loc= ation + * This API provides a single-instruction patching, primarily used for run= time + * code modification. + * By the way, the insn size must be 4 bytes. + */ +int patch_insn_write(void *addr, u32 insn) +{ + u32 *tp =3D addr; + int ret; + + if ((uintptr_t) tp & 0x3) + return -EINVAL; + + ret =3D __patch_insn_write(tp, insn); + + return ret; +} diff --git a/arch/openrisc/mm/init.c b/arch/openrisc/mm/init.c index e4904ca6f0a0..9382d9a0ec78 100644 --- a/arch/openrisc/mm/init.c +++ b/arch/openrisc/mm/init.c @@ -226,7 +226,11 @@ static int __init map_page(unsigned long va, phys_addr= _t pa, pgprot_t prot) return 0; } =20 -void __init __set_fixmap(enum fixed_addresses idx, +/* + * __set_fix must now support both EARLYCON and TEXT_POKE mappings, + * which are used at different stages of kernel execution. + */ +void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot) { unsigned long address =3D __fix_to_virt(idx); --=20 2.45.2