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[54.170.241.106]) by smtp.gmail.com with ESMTPSA id a28-20020a5d457c000000b00317f70240afsm2206607wrc.27.2023.08.31.06.12.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 31 Aug 2023 06:12:32 -0700 (PDT) From: Puranjay Mohan To: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, pulehui@huawei.com, conor.dooley@microchip.com, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, kpsingh@kernel.org, bjorn@kernel.org, bpf@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Cc: puranjay12@gmail.com Subject: [PATCH bpf-next v4 2/4] riscv: extend patch_text_nosync() for multiple pages Date: Thu, 31 Aug 2023 13:12:27 +0000 Message-Id: <20230831131229.497941-3-puranjay12@gmail.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230831131229.497941-1-puranjay12@gmail.com> References: <20230831131229.497941-1-puranjay12@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The patch_insn_write() function currently doesn't work for multiple pages of instructions, therefore patch_text_nosync() will fail with a page fault if called with lengths spanning multiple pages. This commit extends the patch_insn_write() function to support multiple pages by copying at max 2 pages at a time in a loop. This implementation is similar to text_poke_copy() function of x86. Signed-off-by: Puranjay Mohan Reviewed-by: Pu Lehui Reviewed-by: Bj=C3=B6rn T=C3=B6pel Tested-by: Bj=C3=B6rn T=C3=B6pel --- arch/riscv/kernel/patch.c | 37 ++++++++++++++++++++++++++++++++----- 1 file changed, 32 insertions(+), 5 deletions(-) diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c index 575e71d6c8ae..2c97e246f4dc 100644 --- a/arch/riscv/kernel/patch.c +++ b/arch/riscv/kernel/patch.c @@ -53,12 +53,18 @@ static void patch_unmap(int fixmap) } NOKPROBE_SYMBOL(patch_unmap); =20 -static int patch_insn_write(void *addr, const void *insn, size_t len) +static int __patch_insn_write(void *addr, const void *insn, size_t len) { void *waddr =3D addr; bool across_pages =3D (((uintptr_t) addr & ~PAGE_MASK) + len) > PAGE_SIZE; int ret; =20 + /* + * Only two pages can be mapped at a time for writing. + */ + if (len + offset_in_page(addr) > 2 * PAGE_SIZE) + return -EINVAL; + /* * Before reaching here, it was expected to lock the text_mutex * already, so we don't need to give another lock here and could @@ -74,7 +80,7 @@ static int patch_insn_write(void *addr, const void *insn,= size_t len) lockdep_assert_held(&text_mutex); =20 if (across_pages) - patch_map(addr + len, FIX_TEXT_POKE1); + patch_map(addr + PAGE_SIZE, FIX_TEXT_POKE1); =20 waddr =3D patch_map(addr, FIX_TEXT_POKE0); =20 @@ -87,15 +93,36 @@ static int patch_insn_write(void *addr, const void *ins= n, size_t len) =20 return ret; } -NOKPROBE_SYMBOL(patch_insn_write); +NOKPROBE_SYMBOL(__patch_insn_write); #else -static int patch_insn_write(void *addr, const void *insn, size_t len) +static int __patch_insn_write(void *addr, const void *insn, size_t len) { return copy_to_kernel_nofault(addr, insn, len); } -NOKPROBE_SYMBOL(patch_insn_write); +NOKPROBE_SYMBOL(__patch_insn_write); #endif /* CONFIG_MMU */ =20 +static int patch_insn_write(void *addr, const void *insn, size_t len) +{ + size_t patched =3D 0; + size_t size; + int ret =3D 0; + + /* + * Copy the instructions to the destination address, two pages at a time + * because __patch_insn_write() can only handle len <=3D 2 * PAGE_SIZE. + */ + while (patched < len && !ret) { + size =3D min_t(size_t, PAGE_SIZE * 2 - offset_in_page(addr + patched), l= en - patched); + ret =3D __patch_insn_write(addr + patched, insn + patched, size); + + patched +=3D size; + } + + return ret; +} +NOKPROBE_SYMBOL(patch_insn_write); + int patch_text_nosync(void *addr, const void *insns, size_t len) { u32 *tp =3D addr; --=20 2.39.2