Output two new lines per processor in /proc/cpuinfo:

  isa bases       : <bases that all harts conform to>
  hart isa bases  : <bases that this specific hart conforms to>

These read directly from the cached riscv_isa_bases and
hart_isa[cpu].isa_bases bitmaps populated at boot by
riscv_init_isa_bases().

Example output on qemu booted with -cpu rva23s64,sv39=on,pmp=on
(showing only the new lines plus their neighbors for context):

  processor       : 0
  hart            : 4
  isa bases       : rv64ima rva23u64
  isa             : rv64imafdcbvh_zicbom_zicbop_...
  mmu             : sv39
  ...
  mimpid          : 0x0
  hart isa bases  : rv64ima rva23u64
  hart isa        : rv64imafdcbvh_zicbom_zicbop_...

Signed-off-by: Andrew Jones <andrew.jones@oss.qualcomm.com>
Signed-off-by: Guodong Xu <guodong@riscstar.com>
---
v2:
- Read from the cached riscv_isa_bases and hart_isa[cpu_id].isa_bases
  bitmaps populated by riscv_init_isa_bases() at init time.
---
 arch/riscv/kernel/cpu.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 3dbc8cc557dd1..31e2857dcdcf1 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -305,6 +305,26 @@ static void print_mmu(struct seq_file *f)
 	seq_printf(f, "mmu\t\t: %s\n", sv_type);
 }
 
+static const char * const riscv_isa_base_names[] = {
+#ifdef CONFIG_32BIT
+	[RISCV_ISA_BASE_IMA] = "rv32ima",
+#else
+	[RISCV_ISA_BASE_IMA] = "rv64ima",
+#endif
+	[RISCV_ISA_BASE_RVA23U64] = "rva23u64",
+};
+
+static void print_isa_bases(struct seq_file *m, const unsigned long *isa_bases)
+{
+	unsigned int i;
+
+	for (i = 0; i < RISCV_NR_ISA_BASES; i++) {
+		if (test_bit(i, isa_bases))
+			seq_printf(m, " %s", riscv_isa_base_names[i]);
+	}
+	seq_puts(m, "\n");
+}
+
 static void *c_start(struct seq_file *m, loff_t *pos)
 {
 	if (*pos == nr_cpu_ids)
@@ -336,6 +356,9 @@ static int c_show(struct seq_file *m, void *v)
 	seq_printf(m, "processor\t: %lu\n", cpu_id);
 	seq_printf(m, "hart\t\t: %lu\n", cpuid_to_hartid_map(cpu_id));
 
+	seq_puts(m, "isa bases\t:");
+	print_isa_bases(m, riscv_isa_bases);
+
 	/*
 	 * For historical raisins, the isa: line is limited to the lowest common
 	 * denominator of extensions supported across all harts. A true list of
@@ -360,6 +383,9 @@ static int c_show(struct seq_file *m, void *v)
 	seq_printf(m, "marchid\t\t: 0x%lx\n", ci->marchid);
 	seq_printf(m, "mimpid\t\t: 0x%lx\n", ci->mimpid);
 
+	seq_puts(m, "hart isa bases\t:");
+	print_isa_bases(m, hart_isa[cpu_id].isa_bases);
+
 	/*
 	 * Print the ISA extensions specific to this hart, which may show
 	 * additional extensions not present across all harts.

-- 
2.43.0