Messages in this thread | | | From | Huacai Chen <> | Date | Mon, 17 Oct 2022 15:40:46 +0800 | Subject | Re: [PATCH V2] LoongArch: Add unaligned access support |
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Hi, Xuerui,
On Mon, Oct 17, 2022 at 2:07 PM WANG Xuerui <kernel@xen0n.name> wrote: > > On 2022/10/17 10:23, Huacai Chen wrote: > > Loongson-2 series (Loongson-2K500, Loongson-2K1000) don't support > > unaligned access in hardware, while Loongson-3 series (Loongson-3A5000, > > Loongson-3C5000) are configurable whether support unaligned access in > > hardware. This patch add unaligned access emulation for those LoongArch > > processors without hardware support. > > > > Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> > > --- > > V2: Simplify READ_FPR and WRITE_FPR. > > > > arch/loongarch/Kconfig | 2 + > > arch/loongarch/include/asm/inst.h | 14 ++ > > arch/loongarch/kernel/Makefile | 3 +- > > arch/loongarch/kernel/traps.c | 27 ++ > > arch/loongarch/kernel/unaligned.c | 393 ++++++++++++++++++++++++++++++ > > arch/loongarch/lib/Makefile | 2 +- > > arch/loongarch/lib/unaligned.S | 93 +++++++ > > 7 files changed, 532 insertions(+), 2 deletions(-) > > create mode 100644 arch/loongarch/kernel/unaligned.c > > create mode 100644 arch/loongarch/lib/unaligned.S > > Please also update Documentation/admin-guide/sysctl/kernel.rst to > mention loongarch in the respective sysctls' documentation. (Grep for > ARCH_UNALIGN to see.) OK, thanks.
> > > > > diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig > > index 0a6ef613124c..a8dc58e8162a 100644 > > --- a/arch/loongarch/Kconfig > > +++ b/arch/loongarch/Kconfig > > @@ -122,6 +122,8 @@ config LOONGARCH > > select RTC_LIB > > select SMP > > select SPARSE_IRQ > > + select SYSCTL_ARCH_UNALIGN_ALLOW > > + select SYSCTL_ARCH_UNALIGN_NO_WARN > > select SYSCTL_EXCEPTION_TRACE > > select SWIOTLB > > select TRACE_IRQFLAGS_SUPPORT > > diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h > > index fce1843ceebb..e96b5345f389 100644 > > --- a/arch/loongarch/include/asm/inst.h > > +++ b/arch/loongarch/include/asm/inst.h > > @@ -76,6 +76,10 @@ enum reg2i12_op { > > ldbu_op = 0xa8, > > ldhu_op = 0xa9, > > ldwu_op = 0xaa, > > + flds_op = 0xac, > > + fsts_op = 0xad, > > + fldd_op = 0xae, > > + fstd_op = 0xaf, > > }; > > > > enum reg2i14_op { > > @@ -146,6 +150,10 @@ enum reg3_op { > > ldxbu_op = 0x7040, > > ldxhu_op = 0x7048, > > ldxwu_op = 0x7050, > > + fldxs_op = 0x7060, > > + fldxd_op = 0x7068, > > + fstxs_op = 0x7070, > > + fstxd_op = 0x7078, > > amswapw_op = 0x70c0, > > amswapd_op = 0x70c1, > > amaddw_op = 0x70c2, > > @@ -566,4 +574,10 @@ static inline void emit_##NAME(union loongarch_instruction *insn, \ > > > > DEF_EMIT_REG3SA2_FORMAT(alsld, alsld_op) > > > > +struct pt_regs; > > + > > +unsigned long unaligned_read(void *addr, void *value, unsigned long n, bool sign); > > +unsigned long unaligned_write(void *addr, unsigned long value, unsigned long n); > > +void emulate_load_store_insn(struct pt_regs *regs, void __user *addr, unsigned int *pc); > > + > > #endif /* _ASM_INST_H */ > > diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile > > index 42be564278fa..2ad2555b53ea 100644 > > --- a/arch/loongarch/kernel/Makefile > > +++ b/arch/loongarch/kernel/Makefile > > @@ -7,7 +7,8 @@ extra-y := vmlinux.lds > > > > obj-y += head.o cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \ > > traps.o irq.o idle.o process.o dma.o mem.o io.o reset.o switch.o \ > > - elf.o syscall.o signal.o time.o topology.o inst.o ptrace.o vdso.o > > + elf.o syscall.o signal.o time.o topology.o inst.o ptrace.o vdso.o \ > > + unaligned.o > > > > obj-$(CONFIG_ACPI) += acpi.o > > obj-$(CONFIG_EFI) += efi.o > > diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c > > index 1a4dce84ebc6..7ea62faeeadb 100644 > > --- a/arch/loongarch/kernel/traps.c > > +++ b/arch/loongarch/kernel/traps.c > > @@ -368,13 +368,40 @@ asmlinkage void noinstr do_ade(struct pt_regs *regs) > > irqentry_exit(regs, state); > > } > > > > +/* sysctl hooks */ > > +int unaligned_enabled __read_mostly = 1; /* Enabled by default */ > > +int no_unaligned_warning __read_mostly = 1; /* Only 1 warning by default */ > > + > > asmlinkage void noinstr do_ale(struct pt_regs *regs) > > { > > + unsigned int *pc; > > irqentry_state_t state = irqentry_enter(regs); > > > > + perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, regs->csr_badvaddr); > > + > > + /* > > + * Did we catch a fault trying to load an instruction? > > + */ > > + if (regs->csr_badvaddr == regs->csr_era) > > + goto sigbus; > > + if (user_mode(regs) && !test_thread_flag(TIF_FIXADE)) > > + goto sigbus; > > + if (!unaligned_enabled) > > + goto sigbus; > > + if (!no_unaligned_warning) > > + show_registers(regs); > > + > > + pc = (unsigned int *)exception_era(regs); > > + > > + emulate_load_store_insn(regs, (void __user *)regs->csr_badvaddr, pc); > > + > > + goto out; > > + > > +sigbus: > > die_if_kernel("Kernel ale access", regs); > > force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)regs->csr_badvaddr); > > > > +out: > > irqentry_exit(regs, state); > > } > > > > diff --git a/arch/loongarch/kernel/unaligned.c b/arch/loongarch/kernel/unaligned.c > > new file mode 100644 > > index 000000000000..f367424b762a > > --- /dev/null > > +++ b/arch/loongarch/kernel/unaligned.c > > @@ -0,0 +1,393 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * Handle unaligned accesses by emulation. > > + * > > + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited > > MIPS heritage too? > > > + * > > + */ > > +#include <linux/mm.h> > > +#include <linux/sched.h> > > +#include <linux/signal.h> > > +#include <linux/debugfs.h> > > +#include <linux/perf_event.h> > > + > > +#include <asm/asm.h> > > +#include <asm/branch.h> > > +#include <asm/fpu.h> > > +#include <asm/inst.h> > > + > > +#include "access-helper.h" > > + > > +#ifdef CONFIG_DEBUG_FS > > +static u32 unaligned_instructions_user; > > +static u32 unaligned_instructions_kernel; > > +#endif > > + > > +static inline unsigned long read_fpr(unsigned int fd) > > +{ > > +#define READ_FPR(fd, __value) \ > > + __asm__ __volatile__("movfr2gr.d %0, $f"#fd"\n\t" : "=r"(__value)); > > + > > + unsigned long __value; > > + > > + switch (fd) { > > + case 0: > > + READ_FPR(0, __value); > > + break; > > + case 1: > > + READ_FPR(1, __value); > > + break; > > + case 2: > > + READ_FPR(2, __value); > > + break; > > + case 3: > > + READ_FPR(3, __value); > > + break; > > + case 4: > > + READ_FPR(4, __value); > > + break; > > + case 5: > > + READ_FPR(5, __value); > > + break; > > + case 6: > > + READ_FPR(6, __value); > > + break; > > + case 7: > > + READ_FPR(7, __value); > > + break; > > + case 8: > > + READ_FPR(8, __value); > > + break; > > + case 9: > > + READ_FPR(9, __value); > > + break; > > + case 10: > > + READ_FPR(10, __value); > > + break; > > + case 11: > > + READ_FPR(11, __value); > > + break; > > + case 12: > > + READ_FPR(12, __value); > > + break; > > + case 13: > > + READ_FPR(13, __value); > > + break; > > + case 14: > > + READ_FPR(14, __value); > > + break; > > + case 15: > > + READ_FPR(15, __value); > > + break; > > + case 16: > > + READ_FPR(16, __value); > > + break; > > + case 17: > > + READ_FPR(17, __value); > > + break; > > + case 18: > > + READ_FPR(18, __value); > > + break; > > + case 19: > > + READ_FPR(19, __value); > > + break; > > + case 20: > > + READ_FPR(20, __value); > > + break; > > + case 21: > > + READ_FPR(21, __value); > > + break; > > + case 22: > > + READ_FPR(22, __value); > > + break; > > + case 23: > > + READ_FPR(23, __value); > > + break; > > + case 24: > > + READ_FPR(24, __value); > > + break; > > + case 25: > > + READ_FPR(25, __value); > > + break; > > + case 26: > > + READ_FPR(26, __value); > > + break; > > + case 27: > > + READ_FPR(27, __value); > > + break; > > + case 28: > > + READ_FPR(28, __value); > > + break; > > + case 29: > > + READ_FPR(29, __value); > > + break; > > + case 30: > > + READ_FPR(30, __value); > > + break; > > + case 31: > > + READ_FPR(31, __value); > > + break; > > + default: > > + panic("unexpected fd '%d'", fd); > > So this is a bit misleading, I was thinking of file descriptors when I > was reading Feiyang's review comments... maybe something as simple as > "idx", "num" or "regno" will do? OK, idx is better.
> > > + } > > +#undef READ_FPR > > + return __value; > > +} > > + > > +static inline void write_fpr(unsigned int fd, unsigned long value) > > +{ > > +#define WRITE_FPR(fd, value) \ > > + __asm__ __volatile__("movgr2fr.d $f"#fd", %0\n\t" :: "r"(value)); > > + > > + switch (fd) { > > + case 0: > > + WRITE_FPR(0, value); > > + break; > > + case 1: > > + WRITE_FPR(1, value); > > + break; > > + case 2: > > + WRITE_FPR(2, value); > > + break; > > + case 3: > > + WRITE_FPR(3, value); > > + break; > > + case 4: > > + WRITE_FPR(4, value); > > + break; > > + case 5: > > + WRITE_FPR(5, value); > > + break; > > + case 6: > > + WRITE_FPR(6, value); > > + break; > > + case 7: > > + WRITE_FPR(7, value); > > + break; > > + case 8: > > + WRITE_FPR(8, value); > > + break; > > + case 9: > > + WRITE_FPR(9, value); > > + break; > > + case 10: > > + WRITE_FPR(10, value); > > + break; > > + case 11: > > + WRITE_FPR(11, value); > > + break; > > + case 12: > > + WRITE_FPR(12, value); > > + break; > > + case 13: > > + WRITE_FPR(13, value); > > + break; > > + case 14: > > + WRITE_FPR(14, value); > > + break; > > + case 15: > > + WRITE_FPR(15, value); > > + break; > > + case 16: > > + WRITE_FPR(16, value); > > + break; > > + case 17: > > + WRITE_FPR(17, value); > > + break; > > + case 18: > > + WRITE_FPR(18, value); > > + break; > > + case 19: > > + WRITE_FPR(19, value); > > + break; > > + case 20: > > + WRITE_FPR(20, value); > > + break; > > + case 21: > > + WRITE_FPR(21, value); > > + break; > > + case 22: > > + WRITE_FPR(22, value); > > + break; > > + case 23: > > + WRITE_FPR(23, value); > > + break; > > + case 24: > > + WRITE_FPR(24, value); > > + break; > > + case 25: > > + WRITE_FPR(25, value); > > + break; > > + case 26: > > + WRITE_FPR(26, value); > > + break; > > + case 27: > > + WRITE_FPR(27, value); > > + break; > > + case 28: > > + WRITE_FPR(28, value); > > + break; > > + case 29: > > + WRITE_FPR(29, value); > > + break; > > + case 30: > > + WRITE_FPR(30, value); > > + break; > > + case 31: > > + WRITE_FPR(31, value); > > + break; > > + default: > > + panic("unexpected fd '%d'", fd); > > + } > > +#undef WRITE_FPR > > +} > > + > > +void emulate_load_store_insn(struct pt_regs *regs, void __user *addr, unsigned int *pc) > > +{ > > + bool user = user_mode(regs); > > + unsigned int res; > > + unsigned long origpc; > > + unsigned long origra; > > + unsigned long value = 0; > > + union loongarch_instruction insn; > > + > > + origpc = (unsigned long)pc; > > + origra = regs->regs[1]; > > + > > + perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, 0); > > + > > + /* > > + * This load never faults. > > + */ > > + __get_inst(&insn.word, pc, user); > > + if (user && !access_ok(addr, 8)) > > + goto sigbus; > > + > > + if (insn.reg2i12_format.opcode == ldd_op || > > + insn.reg2i14_format.opcode == ldptrd_op || > > + insn.reg3_format.opcode == ldxd_op) { > > + res = unaligned_read(addr, &value, 8, 1); > > + if (res) > > + goto fault; > > + regs->regs[insn.reg2i12_format.rd] = value; > > + } else if (insn.reg2i12_format.opcode == ldw_op || > > + insn.reg2i14_format.opcode == ldptrw_op || > > + insn.reg3_format.opcode == ldxw_op) { > > + res = unaligned_read(addr, &value, 4, 1); > > + if (res) > > + goto fault; > > + regs->regs[insn.reg2i12_format.rd] = value; > > + } else if (insn.reg2i12_format.opcode == ldwu_op || > > + insn.reg3_format.opcode == ldxwu_op) { > > + res = unaligned_read(addr, &value, 4, 0); > > + if (res) > > + goto fault; > > + regs->regs[insn.reg2i12_format.rd] = value; > > + } else if (insn.reg2i12_format.opcode == ldh_op || > > + insn.reg3_format.opcode == ldxh_op) { > > + res = unaligned_read(addr, &value, 2, 1); > > + if (res) > > + goto fault; > > + regs->regs[insn.reg2i12_format.rd] = value; > > + } else if (insn.reg2i12_format.opcode == ldhu_op || > > + insn.reg3_format.opcode == ldxhu_op) { > > + res = unaligned_read(addr, &value, 2, 0); > > + if (res) > > + goto fault; > > + regs->regs[insn.reg2i12_format.rd] = value; > > + } else if (insn.reg2i12_format.opcode == std_op || > > + insn.reg2i14_format.opcode == stptrd_op || > > + insn.reg3_format.opcode == stxd_op) { > > + value = regs->regs[insn.reg2i12_format.rd]; > > + res = unaligned_write(addr, value, 8); > > + if (res) > > + goto fault; > > + } else if (insn.reg2i12_format.opcode == stw_op || > > + insn.reg2i14_format.opcode == stptrw_op || > > + insn.reg3_format.opcode == stxw_op) { > > + value = regs->regs[insn.reg2i12_format.rd]; > > + res = unaligned_write(addr, value, 4); > > + if (res) > > + goto fault; > > + } else if (insn.reg2i12_format.opcode == sth_op || > > + insn.reg3_format.opcode == stxh_op) { > > + value = regs->regs[insn.reg2i12_format.rd]; > > + res = unaligned_write(addr, value, 2); > > + if (res) > > + goto fault; > > + } else if (insn.reg2i12_format.opcode == fldd_op || > > + insn.reg3_format.opcode == fldxd_op) { > > + res = unaligned_read(addr, &value, 8, 1); > > + if (res) > > + goto fault; > > + write_fpr(insn.reg2i12_format.rd, value); > > + } else if (insn.reg2i12_format.opcode == flds_op || > > + insn.reg3_format.opcode == fldxs_op) { > > + res = unaligned_read(addr, &value, 4, 1); > > + if (res) > > + goto fault; > > + write_fpr(insn.reg2i12_format.rd, value); > > + } else if (insn.reg2i12_format.opcode == fstd_op || > > + insn.reg3_format.opcode == fstxd_op) { > > + value = read_fpr(insn.reg2i12_format.rd); > > + res = unaligned_write(addr, value, 8); > > + if (res) > > + goto fault; > > + } else if (insn.reg2i12_format.opcode == fsts_op || > > + insn.reg3_format.opcode == fstxs_op) { > > + value = read_fpr(insn.reg2i12_format.rd); > > + res = unaligned_write(addr, value, 4); > > + if (res) > > + goto fault; > > + } else > > + goto sigbus; > > + > > + > > +#ifdef CONFIG_DEBUG_FS > > + if (user) > > + unaligned_instructions_user++; > > + else > > + unaligned_instructions_kernel++; > > +#endif > > + > > + compute_return_era(regs); > > + return; > > + > > +fault: > > + /* roll back jump/branch */ > > + regs->csr_era = origpc; > > + regs->regs[1] = origra; > > + /* Did we have an exception handler installed? */ > > + if (fixup_exception(regs)) > > + return; > > + > > + die_if_kernel("Unhandled kernel unaligned access", regs); > > + force_sig(SIGSEGV); > > + > > + return; > > + > > +sigbus: > > + die_if_kernel("Unhandled kernel unaligned access", regs); > > + force_sig(SIGBUS); > > + > > + return; > > +} > > + > > +#ifdef CONFIG_DEBUG_FS > > +static int __init debugfs_unaligned(void) > > +{ > > + struct dentry *d; > > + > > + d = debugfs_create_dir("loongarch", NULL); > > + if (!d) > > + return -ENOMEM; > > + > > + debugfs_create_u32("unaligned_instructions_user", > > + S_IRUGO, d, &unaligned_instructions_user); > > + debugfs_create_u32("unaligned_instructions_kernel", > > + S_IRUGO, d, &unaligned_instructions_kernel); > > + > > + return 0; > > +} > > +arch_initcall(debugfs_unaligned); > > +#endif > > diff --git a/arch/loongarch/lib/Makefile b/arch/loongarch/lib/Makefile > > index e36635fccb69..867895530340 100644 > > --- a/arch/loongarch/lib/Makefile > > +++ b/arch/loongarch/lib/Makefile > > @@ -3,4 +3,4 @@ > > # Makefile for LoongArch-specific library files. > > # > > > > -lib-y += delay.o clear_user.o copy_user.o dump_tlb.o > > +lib-y += delay.o clear_user.o copy_user.o dump_tlb.o unaligned.o > > diff --git a/arch/loongarch/lib/unaligned.S b/arch/loongarch/lib/unaligned.S > > new file mode 100644 > > index 000000000000..03210cb5a18d > > --- /dev/null > > +++ b/arch/loongarch/lib/unaligned.S > > @@ -0,0 +1,93 @@ > > +/* SPDX-License-Identifier: GPL-2.0 */ > > +/* > > + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited > > + */ > > + > > +#include <linux/linkage.h> > > + > > +#include <asm/asm.h> > > +#include <asm/asmmacro.h> > > +#include <asm/errno.h> > > +#include <asm/export.h> > > +#include <asm/regdef.h> > > + > > +.macro fixup_ex from, to, fix > > +.if \fix > > + .section .fixup, "ax" > > +\to: li.w a0, -EFAULT > > + jr ra > > + .previous > > +.endif > > + .section __ex_table, "a" > > + PTR \from\()b, \to\()b > > + .previous > > +.endm > > + > > +/* > > + * unsigned long unaligned_read(void *addr, void *value, unsigned long n, bool sign) > > + * > > + * a0: addr > > + * a1: value > > + * a2: n > > + * a3: sign > > + */ > > +SYM_FUNC_START(unaligned_read) > > + beqz a2, 5f > > + > > + li.w t1, 8 > > + li.w t2, 0 > > + > > + addi.d t0, a2, -1 > > + mul.d t1, t0, t1 > > Remove the `t1 = 8` above, then `slli.d t1, t0, 3` here would be enough > and one cycle is saved. OK, thanks.
Huacai > > > + add.d a0, a0, t0 > > + > > + beq a3, zero, 2f > > beqz > > > +1: ld.b t3, a0, 0 > > + b 3f > > + > > +2: ld.bu t3, a0, 0 > > +3: sll.d t3, t3, t1 > > + or t2, t2, t3 > > + addi.d t1, t1, -8 > + addi.d a0, a0, -1 > > + addi.d a2, a2, -1 > > + bgt a2, zero, 2b > > bgtz > > > +4: st.d t2, a1, 0 > > + > > + move a0, a2 > > + jr ra > > + > > +5: li.w a0, -EFAULT > > + jr ra > > + > > + fixup_ex 1, 6, 1 > > + fixup_ex 2, 6, 0 > > + fixup_ex 4, 6, 0 > > +SYM_FUNC_END(unaligned_read) > > + > > +/* > > + * unsigned long unaligned_write(void *addr, unsigned long value, unsigned long n) > > + * > > + * a0: addr > > + * a1: value > > + * a2: n > > + */ > > +SYM_FUNC_START(unaligned_write) > > + beqz a2, 3f > > + > > + li.w t0, 0 > > +1: srl.d t1, a1, t0 > > +2: st.b t1, a0, 0 > > + addi.d t0, t0, 8 > > + addi.d a2, a2, -1 > > + addi.d a0, a0, 1 > > + bgt a2, zero, 1b > > bgtz > > > + > > + move a0, a2 > > + jr ra > > + > > +3: li.w a0, -EFAULT > > + jr ra > > + > > + fixup_ex 2, 4, 1 > > +SYM_FUNC_END(unaligned_write) > > -- > WANG "xen0n" Xuerui > > Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/ > >
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