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Thu, 20 Mar 2025 10:29:34 -0700 (PDT) From: Charlie Jenkins Date: Thu, 20 Mar 2025 10:29:21 -0700 Subject: [PATCH v6 1/4] riscv: entry: Convert ret_from_fork() to C Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250320-riscv_optimize_entry-v6-1-63e187e26041@rivosinc.com> References: <20250320-riscv_optimize_entry-v6-0-63e187e26041@rivosinc.com> In-Reply-To: <20250320-riscv_optimize_entry-v6-0-63e187e26041@rivosinc.com> To: Paul Walmsley , Palmer Dabbelt , Huacai Chen , WANG Xuerui , Thomas Gleixner , Peter Zijlstra , Andy Lutomirski , Alexandre Ghiti , Arnd Bergmann , Albert Ou , Alexandre Ghiti Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, Charlie Jenkins X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=3515; i=charlie@rivosinc.com; h=from:subject:message-id; bh=gaq/v9YuAdYAHAPq6G2li6XLwEhlQb1rcc0R86FQKSc=; b=kA0DAAoWjgFid219CPYByyZiAGfcUHrImYiZNCS0BmPPKWSpiEX0ghY/Of3RasTrPX9qN5AB8 4h1BAAWCgAdFiEEDNaAA4XcL3bFFXaQjgFid219CPYFAmfcUHoACgkQjgFid219CPbRkwEAtPKv Ku03MbxplfH795hgrIKj97bZxGVqLUQ7QpkrN6QBAMINRMdaKpxJoDyr+sPeH8RagpPD/EteNBB ZeabOyrgN X-Developer-Key: i=charlie@rivosinc.com; a=openpgp; fpr=7D834FF11B1D8387E61C776FFB10D1F27D6B1354 Move the main section of ret_from_fork() to C to allow inlining of syscall_exit_to_user_mode(). Signed-off-by: Charlie Jenkins Reviewed-by: Alexandre Ghiti --- arch/riscv/include/asm/asm-prototypes.h | 1 + arch/riscv/kernel/entry.S | 15 ++++++--------- arch/riscv/kernel/process.c | 14 ++++++++++++-- 3 files changed, 19 insertions(+), 11 deletions(-) diff --git a/arch/riscv/include/asm/asm-prototypes.h b/arch/riscv/include/a= sm/asm-prototypes.h index cd627ec289f163a630b73dd03dd52a6b28692997..733ff609778797001006c33bba9= e3cc5b1f15387 100644 --- a/arch/riscv/include/asm/asm-prototypes.h +++ b/arch/riscv/include/asm/asm-prototypes.h @@ -52,6 +52,7 @@ DECLARE_DO_ERROR_INFO(do_trap_ecall_s); DECLARE_DO_ERROR_INFO(do_trap_ecall_m); DECLARE_DO_ERROR_INFO(do_trap_break); =20 +asmlinkage void ret_from_fork(void *fn_arg, int (*fn)(void *), struct pt_r= egs *regs); asmlinkage void handle_bad_stack(struct pt_regs *regs); asmlinkage void do_page_fault(struct pt_regs *regs); asmlinkage void do_irq(struct pt_regs *regs); diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 33a5a9f2a0d4e1eeccfb3621b9e518b88e1b0704..b2dc5e7c7b3a843fa4aa02eba2a= 911eb3ce31d1f 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -319,17 +319,14 @@ SYM_CODE_END(handle_kernel_stack_overflow) ASM_NOKPROBE(handle_kernel_stack_overflow) #endif =20 -SYM_CODE_START(ret_from_fork) +SYM_CODE_START(ret_from_fork_asm) call schedule_tail - beqz s0, 1f /* not from kernel thread */ - /* Call fn(arg) */ - move a0, s1 - jalr s0 -1: - move a0, sp /* pt_regs */ - call syscall_exit_to_user_mode + move a0, s1 /* fn_arg */ + move a1, s0 /* fn */ + move a2, sp /* pt_regs */ + call ret_from_fork j ret_from_exception -SYM_CODE_END(ret_from_fork) +SYM_CODE_END(ret_from_fork_asm) =20 #ifdef CONFIG_IRQ_STACKS /* diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 7c244de7718008947075357ea4502d56419d507c..7b0a0bfe29aec896c2bdd8976d8= 55dd390de88d7 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -17,7 +17,9 @@ #include #include #include +#include =20 +#include #include #include #include @@ -36,7 +38,7 @@ unsigned long __stack_chk_guard __read_mostly; EXPORT_SYMBOL(__stack_chk_guard); #endif =20 -extern asmlinkage void ret_from_fork(void); +extern asmlinkage void ret_from_fork_asm(void); =20 void noinstr arch_cpu_idle(void) { @@ -206,6 +208,14 @@ int arch_dup_task_struct(struct task_struct *dst, stru= ct task_struct *src) return 0; } =20 +asmlinkage void ret_from_fork(void *fn_arg, int (*fn)(void *), struct pt_r= egs *regs) +{ + if (unlikely(fn)) + fn(fn_arg); + + syscall_exit_to_user_mode(regs); +} + int copy_thread(struct task_struct *p, const struct kernel_clone_args *arg= s) { unsigned long clone_flags =3D args->flags; @@ -242,7 +252,7 @@ int copy_thread(struct task_struct *p, const struct ker= nel_clone_args *args) p->thread.riscv_v_flags =3D 0; if (has_vector() || has_xtheadvector()) riscv_v_thread_alloc(p); - p->thread.ra =3D (unsigned long)ret_from_fork; + p->thread.ra =3D (unsigned long)ret_from_fork_asm; p->thread.sp =3D (unsigned long)childregs; /* kernel sp */ return 0; } --=20 2.43.0