@@ -1508,6 +1508,17 @@ config CPU_LOONGSON3_WORKAROUNDS
If unsure, please say Y.
+config CPU_LOONGSON3_CPUCFG_EMULATION
+ bool "Emulate the CPUCFG instruction on older cores"
+ default y
+ depends on CPU_LOONGSON64
+ help
+ Loongson-3A R4 and newer have the CPUCFG instruction available for
+ userland to query CPU capabilities, much like CPUID on x86. This
+ option provides emulation of the instruction on older cores.
+
+ If unsure, please say Y.
+
config CPU_LOONGSON2E
bool "Loongson 2E"
depends on SYS_HAS_CPU_LOONGSON2E
@@ -105,6 +105,15 @@ struct cpuinfo_mips {
unsigned int gtoffset_mask;
unsigned int guestid_mask;
unsigned int guestid_cache;
+
+#ifdef CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION
+ /* CPUCFG data for this CPU, synthesized at probe time.
+ *
+ * CPUCFG select 0 is PRId, others are unimplemented for now. So the
+ * only stored values are for CPUCFG selects 1-3 inclusive.
+ */
+ u32 loongson3_cpucfg_data[3];
+#endif
} __attribute__((aligned(SMP_CACHE_BYTES)));
extern struct cpuinfo_mips cpu_data[];
new file mode 100644
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_MACH_LOONGSON64_CPUCFG_EMUL_H_
+#define _ASM_MACH_LOONGSON64_CPUCFG_EMUL_H_
+
+#include <asm/cpu-info.h>
+
+#include <loongson_regs.h>
+
+#define LOONGSON_FPREV_MASK 0x7
+
+#ifdef CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION
+
+/* Finalize synthesis of CPUCFG data by patching the partially filled data
+ * with dynamically detected CPU characteristics. This keeps the amount of
+ * hard-coded logic at a minimum.
+ */
+void loongson3_cpucfg_finish_synthesis(struct cpuinfo_mips *c);
+
+static inline u32 loongson3_cpucfg_read_synthesized(
+ struct cpuinfo_mips *c,
+ __u64 sel)
+{
+ switch (sel) {
+ case LOONGSON_CFG0:
+ return c->processor_id;
+ case LOONGSON_CFG1:
+ case LOONGSON_CFG2:
+ case LOONGSON_CFG3:
+ return c->loongson3_cpucfg_data[sel - 1];
+ case LOONGSON_CFG4:
+ case LOONGSON_CFG5:
+ /* CPUCFG selects 4 and 5 are related to the processor clock.
+ * Unimplemented for now.
+ */
+ return 0;
+ case LOONGSON_CFG6:
+ /* CPUCFG select 6 is for the undocumented Safe Extension. */
+ return 0;
+ case LOONGSON_CFG7:
+ /* CPUCFG select 7 is for the virtualization extension.
+ * We don't know if the two currently known features are
+ * supported on older cores according to the public
+ * documentation, so leave this at zero.
+ */
+ return 0;
+ }
+
+ /*
+ * Return 0 for unrecognized CPUCFG selects, which is real hardware
+ * behavior observed on Loongson 3A R4.
+ */
+ return 0;
+}
+#else
+static void loongson3_cpucfg_finish_synthesis(struct cpuinfo_mips *c)
+{
+}
+
+static inline u32 loongson3_cpucfg_read_synthesized(
+ struct cpuinfo_mips *c,
+ __u64 sel)
+{
+ return 0;
+}
+#endif
+
+#endif /* _ASM_MACH_LOONGSON64_CPUCFG_EMUL_H_ */
@@ -28,6 +28,8 @@
#include <asm/spram.h>
#include <linux/uaccess.h>
+#include <asm/mach-loongson64/cpucfg-emul.h>
+
/* Hardware capabilities */
unsigned int elf_hwcap __read_mostly;
EXPORT_SYMBOL_GPL(elf_hwcap);
@@ -1580,6 +1582,24 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu)
set_isa(c, MIPS_CPU_ISA_M64R1);
c->ases |= (MIPS_ASE_LOONGSON_MMI | MIPS_ASE_LOONGSON_CAM |
MIPS_ASE_LOONGSON_EXT);
+#ifdef CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION
+ /* Add CPUCFG features non-discoverable otherwise. */
+ c->loongson3_cpucfg_data[0] |= (LOONGSON_CFG1_LSLDR0 |
+ LOONGSON_CFG1_LSSYNCI | LOONGSON_CFG1_LSUCA |
+ LOONGSON_CFG1_LLSYNC | LOONGSON_CFG1_TGTSYNC);
+ c->loongson3_cpucfg_data[1] |= (LOONGSON_CFG2_LBT1 |
+ LOONGSON_CFG2_LPMP | LOONGSON_CFG2_LPM_REV1);
+ c->loongson3_cpucfg_data[2] |= (
+ LOONGSON_CFG3_LCAM_REV1 |
+ LOONGSON_CFG3_LCAMNUM_REV1 |
+ LOONGSON_CFG3_LCAMKW_REV1 |
+ LOONGSON_CFG3_LCAMVW_REV1);
+
+ /* This feature is set by firmware, but all known
+ * Loongson-3A Legacy systems are configured this way.
+ */
+ c->loongson3_cpucfg_data[0] |= LOONGSON_CFG1_CDMAP;
+#endif
break;
case PRID_REV_LOONGSON3B_R1:
case PRID_REV_LOONGSON3B_R2:
@@ -1589,6 +1609,24 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu)
set_isa(c, MIPS_CPU_ISA_M64R1);
c->ases |= (MIPS_ASE_LOONGSON_MMI | MIPS_ASE_LOONGSON_CAM |
MIPS_ASE_LOONGSON_EXT);
+#ifdef CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION
+ /* Add CPUCFG features non-discoverable otherwise. */
+ c->loongson3_cpucfg_data[0] |= (LOONGSON_CFG1_LSLDR0 |
+ LOONGSON_CFG1_LSSYNCI | LOONGSON_CFG1_LSUCA |
+ LOONGSON_CFG1_LLSYNC | LOONGSON_CFG1_TGTSYNC);
+ c->loongson3_cpucfg_data[1] |= (LOONGSON_CFG2_LBT1 |
+ LOONGSON_CFG2_LPMP | LOONGSON_CFG2_LPM_REV1);
+ c->loongson3_cpucfg_data[2] |= (
+ LOONGSON_CFG3_LCAM_REV1 |
+ LOONGSON_CFG3_LCAMNUM_REV1 |
+ LOONGSON_CFG3_LCAMKW_REV1 |
+ LOONGSON_CFG3_LCAMVW_REV1);
+
+ /* This feature is set by firmware, but all known
+ * Loongson-3B Legacy systems are configured this way.
+ */
+ c->loongson3_cpucfg_data[0] |= LOONGSON_CFG1_CDMAP;
+#endif
break;
}
@@ -1957,9 +1995,57 @@ static inline void decode_cpucfg(struct cpuinfo_mips *c)
c->ases |= MIPS_ASE_LOONGSON_CAM;
}
+#ifdef CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION
+static inline int cpu_has_uca(void)
+{
+ u32 diag = read_c0_diag();
+ u32 new_diag;
+
+ if (diag & LOONGSON_DIAG_UCAC)
+ /* UCA is already enabled. */
+ return 1;
+
+ /* See if UCAC bit can be flipped on. This should be safe. */
+ new_diag = diag | LOONGSON_DIAG_UCAC;
+ write_c0_diag(new_diag);
+ new_diag = read_c0_diag();
+ write_c0_diag(diag);
+
+ return (new_diag & LOONGSON_DIAG_UCAC) != 0;
+}
+
+static inline void probe_uca(struct cpuinfo_mips *c)
+{
+ if (cpu_has_uca())
+ c->loongson3_cpucfg_data[0] |= LOONGSON_CFG1_LSUCA;
+}
+
+static inline void decode_loongson_config6(struct cpuinfo_mips *c)
+{
+ u32 config6 = read_c0_config6();
+
+ if (config6 & MIPS_CONF6_LOONGSON_STFILL)
+ c->loongson3_cpucfg_data[0] |= LOONGSON_CFG1_SFBP;
+ if (config6 & MIPS_CONF6_LOONGSON_LLEXC)
+ c->loongson3_cpucfg_data[0] |= LOONGSON_CFG1_LLEXC;
+ if (config6 & MIPS_CONF6_LOONGSON_SCRAND)
+ c->loongson3_cpucfg_data[0] |= LOONGSON_CFG1_SCRAND;
+}
+#else
+static inline void probe_uca(struct cpuinfo_mips *c)
+{
+}
+
+static inline void decode_loongson_config6(struct cpuinfo_mips *c)
+{
+}
+#endif /* CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION */
+
static inline void cpu_probe_loongson(struct cpuinfo_mips *c, unsigned int cpu)
{
decode_configs(c);
+ decode_loongson_config6(c);
+ probe_uca(c);
switch (c->processor_id & PRID_IMP_MASK) {
case PRID_IMP_LOONGSON_64R: /* Loongson-64 Reduced */
@@ -1977,6 +2063,21 @@ static inline void cpu_probe_loongson(struct cpuinfo_mips *c, unsigned int cpu)
c->writecombine = _CACHE_UNCACHED_ACCELERATED;
c->ases |= (MIPS_ASE_LOONGSON_MMI | MIPS_ASE_LOONGSON_EXT |
MIPS_ASE_LOONGSON_EXT2);
+#ifdef CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION
+ /* Add CPUCFG features non-discoverable otherwise. */
+ c->loongson3_cpucfg_data[0] |= (LOONGSON_CFG1_LSLDR0 |
+ LOONGSON_CFG1_LSSYNCI | LOONGSON_CFG1_LLSYNC |
+ LOONGSON_CFG1_TGTSYNC);
+ c->loongson3_cpucfg_data[1] |= (LOONGSON_CFG2_LBT1 |
+ LOONGSON_CFG2_LBT2 | LOONGSON_CFG2_LPMP |
+ LOONGSON_CFG2_LPM_REV2);
+ c->loongson3_cpucfg_data[2] = 0;
+
+ /* This feature is set by firmware, but all known Loongson-2K
+ * systems are configured this way.
+ */
+ c->loongson3_cpucfg_data[0] |= LOONGSON_CFG1_CDMAP;
+#endif
break;
case PRID_IMP_LOONGSON_64C: /* Loongson-3 Classic */
switch (c->processor_id & PRID_REV_MASK) {
@@ -2007,6 +2108,26 @@ static inline void cpu_probe_loongson(struct cpuinfo_mips *c, unsigned int cpu)
c->writecombine = _CACHE_UNCACHED_ACCELERATED;
c->ases |= (MIPS_ASE_LOONGSON_MMI | MIPS_ASE_LOONGSON_CAM |
MIPS_ASE_LOONGSON_EXT | MIPS_ASE_LOONGSON_EXT2);
+#ifdef CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION
+ /* Add CPUCFG features non-discoverable otherwise. */
+ c->loongson3_cpucfg_data[0] |= (LOONGSON_CFG1_CNT64 |
+ LOONGSON_CFG1_LSLDR0 | LOONGSON_CFG1_LSPREF |
+ LOONGSON_CFG1_LSPREFX | LOONGSON_CFG1_LSSYNCI |
+ LOONGSON_CFG1_LLSYNC | LOONGSON_CFG1_TGTSYNC);
+ c->loongson3_cpucfg_data[1] |= (LOONGSON_CFG2_LBT1 |
+ LOONGSON_CFG2_LBT2 | LOONGSON_CFG2_LBTMMU |
+ LOONGSON_CFG2_LPMP | LOONGSON_CFG2_LPM_REV1 |
+ LOONGSON_CFG2_LVZ_REV1);
+ c->loongson3_cpucfg_data[2] |= (LOONGSON_CFG3_LCAM_REV1 |
+ LOONGSON_CFG3_LCAMNUM_REV1 |
+ LOONGSON_CFG3_LCAMKW_REV1 |
+ LOONGSON_CFG3_LCAMVW_REV1);
+
+ /* This feature is set by firmware, but all known Loongson-3
+ * systems are configured this way.
+ */
+ c->loongson3_cpucfg_data[0] |= LOONGSON_CFG1_CDMAP;
+#endif
break;
case PRID_IMP_LOONGSON_64G:
c->cputype = CPU_LOONGSON64;
@@ -2200,6 +2321,12 @@ void cpu_probe(void)
c->fpu_csr31 = FPU_CSR_RN;
c->fpu_msk31 = FPU_CSR_RSVD | FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
+#ifdef CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION
+ c->loongson3_cpucfg_data[0] = 0;
+ c->loongson3_cpucfg_data[1] = 0;
+ c->loongson3_cpucfg_data[2] = 0;
+#endif
+
c->processor_id = read_c0_prid();
switch (c->processor_id & PRID_COMP_MASK) {
case PRID_COMP_LEGACY:
@@ -2333,6 +2460,8 @@ void cpu_probe(void)
if (cpu_has_vz)
cpu_probe_vz(c);
+ loongson3_cpucfg_finish_synthesis(c);
+
cpu_probe_vmbits(c);
#ifdef CONFIG_64BIT
@@ -71,6 +71,8 @@
#include <asm/tlbex.h>
#include <asm/uasm.h>
+#include <asm/mach-loongson64/cpucfg-emul.h>
+
extern void check_wait(void);
extern asmlinkage void rollback_handle_int(void);
extern asmlinkage void handle_int(void);
@@ -693,6 +695,44 @@ static int simulate_sync(struct pt_regs *regs, unsigned int opcode)
return -1; /* Must be something else ... */
}
+/*
+ * Loongson-3 CSR instructions emulation
+ */
+
+#ifdef CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION
+
+#define LWC2 0xc8000000
+#define RS BASE
+#define CSR_OPCODE2 0x00000118
+#define CSR_OPCODE2_MASK 0x000007ff
+#define CSR_FUNC_MASK RT
+#define CSR_FUNC_CPUCFG 0x8
+
+static int simulate_loongson3_cpucfg(struct pt_regs *regs,
+ unsigned int opcode)
+{
+ int op = opcode & OPCODE;
+ int op2 = opcode & CSR_OPCODE2_MASK;
+ int csr_func = (opcode & CSR_FUNC_MASK) >> 16;
+
+ if (op == LWC2 && op2 == CSR_OPCODE2 && csr_func == CSR_FUNC_CPUCFG) {
+ int rd = (opcode & RD) >> 11;
+ int rs = (opcode & RS) >> 21;
+ __u64 sel = regs->regs[rs];
+
+ perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, 0);
+
+ regs->regs[rd] = loongson3_cpucfg_read_synthesized(
+ ¤t_cpu_data, sel);
+
+ return 0;
+ }
+
+ /* Not ours. */
+ return -1;
+}
+#endif /* CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION */
+
asmlinkage void do_ov(struct pt_regs *regs)
{
enum ctx_state prev_state;
@@ -1166,6 +1206,11 @@ asmlinkage void do_ri(struct pt_regs *regs)
if (status < 0)
status = simulate_fp(regs, opcode, old_epc, old31);
+
+#ifdef CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION
+ if (status < 0)
+ status = simulate_loongson3_cpucfg(regs, opcode);
+#endif
} else if (cpu_has_mmips) {
unsigned short mmop[2] = { 0 };
@@ -10,3 +10,4 @@ obj-$(CONFIG_NUMA) += numa.o
obj-$(CONFIG_RS780_HPET) += hpet.o
obj-$(CONFIG_PCI) += pci.o
obj-$(CONFIG_SUSPEND) += pm.o
+obj-$(CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION) += cpucfg-emul.o
new file mode 100644
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/smp.h>
+#include <asm/cpu.h>
+#include <asm/cpu-info.h>
+
+#include <loongson_regs.h>
+#include <cpucfg-emul.h>
+
+static u32 get_loongson_fprev(struct cpuinfo_mips *c)
+{
+ return (c->fpu_id & LOONGSON_FPREV_MASK) << LOONGSON_CFG1_FPREV_OFFSET;
+}
+
+static void patch_cpucfg_sel1(struct cpuinfo_mips *c)
+{
+ u64 ases = c->ases;
+ u64 options = c->options;
+ u32 data = c->loongson3_cpucfg_data[0];
+
+ if (options & MIPS_CPU_FPU) {
+ data |= LOONGSON_CFG1_FP;
+ data |= get_loongson_fprev(c);
+ }
+ if (ases & MIPS_ASE_LOONGSON_MMI)
+ data |= LOONGSON_CFG1_MMI;
+ if (ases & MIPS_ASE_MSA)
+ data |= LOONGSON_CFG1_MSA1;
+
+ c->loongson3_cpucfg_data[0] = data;
+}
+
+static void patch_cpucfg_sel2(struct cpuinfo_mips *c)
+{
+ u64 ases = c->ases;
+ u64 options = c->options;
+ u32 data = c->loongson3_cpucfg_data[1];
+
+ if (ases & MIPS_ASE_LOONGSON_EXT)
+ data |= LOONGSON_CFG2_LEXT1;
+ if (ases & MIPS_ASE_LOONGSON_EXT2)
+ data |= LOONGSON_CFG2_LEXT2;
+ if (options & MIPS_CPU_LDPTE)
+ data |= LOONGSON_CFG2_LSPW;
+
+ if (ases & MIPS_ASE_VZ)
+ data |= LOONGSON_CFG2_LVZP;
+ else
+ data &= ~LOONGSON_CFG2_LVZREV;
+
+ c->loongson3_cpucfg_data[1] = data;
+}
+
+static void patch_cpucfg_sel3(struct cpuinfo_mips *c)
+{
+ u64 ases = c->ases;
+ u32 data = c->loongson3_cpucfg_data[2];
+
+ if (ases & MIPS_ASE_LOONGSON_CAM) {
+ data |= LOONGSON_CFG3_LCAMP;
+ } else {
+ data &= ~LOONGSON_CFG3_LCAMREV;
+ data &= ~LOONGSON_CFG3_LCAMNUM;
+ data &= ~LOONGSON_CFG3_LCAMKW;
+ data &= ~LOONGSON_CFG3_LCAMVW;
+ }
+
+ c->loongson3_cpucfg_data[2] = data;
+}
+
+void loongson3_cpucfg_finish_synthesis(struct cpuinfo_mips *c)
+{
+ /* CPUs with CPUCFG support don't need to synthesize anything. */
+ if (cpu_has_cfg())
+ return;
+
+ patch_cpucfg_sel1(c);
+ patch_cpucfg_sel2(c);
+ patch_cpucfg_sel3(c);
+}
CPUCFG is the instruction for querying processor characteristics on newer Loongson processors, much like CPUID of x86. Since the instruction is supposedly designed to provide a unified way to do feature detection (without having to, for example, parse /proc/cpuinfo which is too heavyweight), it is important to provide compatibility for older cores without native support. Fortunately, most of the fields can be synthesized without changes to semantics. Performance is not really big a concern, because feature detection logic is not expected to be invoked very often in typical userland applications. The instruction can't be emulated on LOONGSON_2EF cores, according to FlyGoat's experiments. Because the LWC2 opcode is assigned to other valid instructions on 2E and 2F, no RI exception is raised for us to intercept. So compatibility is only extended back furthest to Loongson-3A1000. Loongson-2K is covered too, as it is basically a remix of various blocks from the 3A/3B models from a kernel perspective. This is lightly based on Loongson's work on their Linux 3.10 fork, for being the authority on the right feature flags to fill in, where things aren't otherwise discoverable. Signed-off-by: WANG Xuerui <git@xen0n.name> Cc: Huacai Chen <chenhc@lemote.com> Cc: Jiaxun Yang <jiaxun.yang@flygoat.com> Cc: Tiezhu Yang <yangtiezhu@loongson.cn> --- arch/mips/Kconfig | 11 ++ arch/mips/include/asm/cpu-info.h | 9 ++ .../include/asm/mach-loongson64/cpucfg-emul.h | 67 +++++++++ arch/mips/kernel/cpu-probe.c | 129 ++++++++++++++++++ arch/mips/kernel/traps.c | 45 ++++++ arch/mips/loongson64/Makefile | 1 + arch/mips/loongson64/cpucfg-emul.c | 80 +++++++++++ 7 files changed, 342 insertions(+) create mode 100644 arch/mips/include/asm/mach-loongson64/cpucfg-emul.h create mode 100644 arch/mips/loongson64/cpucfg-emul.c