LoongArch64: Add 'help -r' command support

Add support form printing out the registers from the dump file. We don't
take the registers directly from the ELF notes but instead use the version
we've saved into the machine_specific structure.  If we don't do this,
we'd get misleading output when the number of ELF notes don't match the
number of online CPUs.

E.g. Without this patch:
crash> help -r
CPU 0:
     R0: 0000000000000000   R1: 900000000026cd2c   R2: 90000000013e8000
     R3: 90000000013ebdf0   R4: 9000000005923878   R5: 0000000000000000
     R6: 0000000000000001   R7: 7fffffffffffffff   R8: 0000000000000003
     R9: 9000000094f644a8  R10: ffffffffa9059289  R11: 0000000001167617
    R12: 0000000000000000  R13: 0000000000000002  R14: 0000000000168d9a
    R15: 90000000017fd358  R16: 90000000013fe000  R17: 000001383a11ae73
    R18: fffffffffffffff7  R19: 0000000000000000  R20: 0000000000000954
    R21: 90000000002c65cc  R22: 0000000000000000  R23: 90000000014168d0
    R24: 0000000000000000  R25: 0000000000000004  R26: 90000000014169a8
    R27: 0000000000000004  R28: 900000000150f596  R29: 9000000001257f18
    R30: 0000000000000000  R31: 0000000000000000
    CSR epc : 9000000005923878    CSR badv: 9000000000221620
    CSR crmd: 000000b0            CSR prmd: 90000000014169a8
    CSR ecfg: 00000000           CSR estat: 90000000014168d0
    CSR eneu: 00000004
...

Co-developed-by: Youling Tang <[email protected]>
Signed-off-by: Youling Tang <[email protected]>
Signed-off-by: Ming Wang <[email protected]>

diskdump.c

@@ -2648,6 +2648,9 @@ diskdump_display_regs(int cpu, FILE *ofp)
 
 	if (machine_type("MIPS64"))
 		mips64_display_regs_from_elf_notes(cpu, ofp);
+
+	if (machine_type("LOONGARCH64"))
+		loongarch64_display_regs_from_elf_notes(cpu, ofp);
 }
 
 void
@@ -2659,7 +2662,7 @@ dump_registers_for_compressed_kdump(void)
 	    !(machine_type("X86") || machine_type("X86_64") ||
 	      machine_type("ARM64") || machine_type("PPC64") ||
 	      machine_type("MIPS") || machine_type("MIPS64") ||
-	      machine_type("RISCV64")))
+	      machine_type("RISCV64") || machine_type("LOONGARCH64")))
 		error(FATAL, "-r option not supported for this dumpfile\n");
 
 	if (machine_type("ARM64") && (kt->cpus != dd->num_prstatus_notes))

loongarch64.c

@@ -1269,6 +1269,75 @@ loongarch64_init(int when)
 void
 loongarch64_display_regs_from_elf_notes(int cpu, FILE *ofp)
 {
+	const struct machine_specific *ms = machdep->machspec;
+	struct loongarch64_pt_regs *regs;
+
+	if (!ms->crash_task_regs) {
+		error(INFO, "registers not collected for cpu %d\n", cpu);
+		return;
+	}
+
+	regs = &ms->crash_task_regs[cpu];
+	if (!regs->regs[LOONGARCH64_EF_SP] && !regs->csr_epc) {
+		error(INFO, "registers not collected for cpu %d\n", cpu);
+		return;
+	}
+
+	fprintf(ofp,
+		"     R0: %016lx   R1: %016lx   R2: %016lx\n"
+		"     R3: %016lx   R4: %016lx   R5: %016lx\n"
+		"     R6: %016lx   R7: %016lx   R8: %016lx\n"
+		"     R9: %016lx  R10: %016lx  R11: %016lx\n"
+		"    R12: %016lx  R13: %016lx  R14: %016lx\n"
+		"    R15: %016lx  R16: %016lx  R17: %016lx\n"
+		"    R18: %016lx  R19: %016lx  R20: %016lx\n"
+		"    R21: %016lx  R22: %016lx  R23: %016lx\n"
+		"    R24: %016lx  R25: %016lx  R26: %016lx\n"
+		"    R27: %016lx  R28: %016lx  R29: %016lx\n"
+		"    R30: %016lx  R31: %016lx\n"
+		"    CSR epc : %016lx    CSR badv: %016lx\n"
+		"    CSR crmd: %08lx            CSR prmd: %08lx\n"
+		"    CSR ecfg: %08lx           CSR estat: %08lx\n"
+		"    CSR eneu: %08lx",
+		regs->regs[LOONGARCH64_EF_R0],
+		regs->regs[LOONGARCH64_EF_R0 + 1],
+		regs->regs[LOONGARCH64_EF_R0 + 2],
+		regs->regs[LOONGARCH64_EF_R0 + 3],
+		regs->regs[LOONGARCH64_EF_R0 + 4],
+		regs->regs[LOONGARCH64_EF_R0 + 5],
+		regs->regs[LOONGARCH64_EF_R0 + 6],
+		regs->regs[LOONGARCH64_EF_R0 + 7],
+		regs->regs[LOONGARCH64_EF_R0 + 8],
+		regs->regs[LOONGARCH64_EF_R0 + 9],
+		regs->regs[LOONGARCH64_EF_R0 + 10],
+		regs->regs[LOONGARCH64_EF_R0 + 11],
+		regs->regs[LOONGARCH64_EF_R0 + 12],
+		regs->regs[LOONGARCH64_EF_R0 + 13],
+		regs->regs[LOONGARCH64_EF_R0 + 14],
+		regs->regs[LOONGARCH64_EF_R0 + 15],
+		regs->regs[LOONGARCH64_EF_R0 + 16],
+		regs->regs[LOONGARCH64_EF_R0 + 17],
+		regs->regs[LOONGARCH64_EF_R0 + 18],
+		regs->regs[LOONGARCH64_EF_R0 + 19],
+		regs->regs[LOONGARCH64_EF_R0 + 20],
+		regs->regs[LOONGARCH64_EF_R0 + 21],
+		regs->regs[LOONGARCH64_EF_R0 + 22],
+		regs->regs[LOONGARCH64_EF_R0 + 23],
+		regs->regs[LOONGARCH64_EF_R0 + 24],
+		regs->regs[LOONGARCH64_EF_R0 + 25],
+		regs->regs[LOONGARCH64_EF_R0 + 26],
+		regs->regs[LOONGARCH64_EF_R0 + 27],
+		regs->regs[LOONGARCH64_EF_R0 + 28],
+		regs->regs[LOONGARCH64_EF_R0 + 29],
+		regs->regs[LOONGARCH64_EF_R0 + 30],
+		regs->regs[LOONGARCH64_EF_R0 + 31],
+		regs->csr_epc,
+		regs->csr_badvaddr,
+		regs->csr_crmd,
+		regs->csr_prmd,
+		regs->csr_ecfg,
+		regs->csr_estat,
+		regs->csr_euen);
 }
 
 #else /* !LOONGARCH64 */

netdump.c

@@ -2961,6 +2961,8 @@ display_regs_from_elf_notes(int cpu, FILE *ofp)
 		mips64_display_regs_from_elf_notes(cpu, ofp);
 	} else if (machine_type("RISCV64")) {
 		riscv64_display_regs_from_elf_notes(cpu, ofp);
+	} else if (machine_type("LOONGARCH64")) {
+		loongarch64_display_regs_from_elf_notes(cpu, ofp);
 	}
 }
 
@@ -2972,7 +2974,7 @@ dump_registers_for_elf_dumpfiles(void)
         if (!(machine_type("X86") || machine_type("X86_64") || 
 	    machine_type("ARM64") || machine_type("PPC64") ||
 	    machine_type("MIPS") || machine_type("MIPS64") ||
-	    machine_type("RISCV64")))
+	    machine_type("RISCV64") || machine_type("LOONGARCH64")))
                 error(FATAL, "-r option not supported for this dumpfile\n");
 
 	if (NETDUMP_DUMPFILE()) {