setup: track BSP CPU ID via common interface

Add get_bsp_cpu_id() and set_bsp_cpu_id() helper functions. Update bsp variable on BSP's percpu page upon both ACPI and MP tables enumeration. Do not use bitfield for storing percpu variables. And also rename id to cpu_id. Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
KernelTestFramework · Oct 28, 2020 · 1d4e794 · 1d4e794
1 parent f379bfa
commit 1d4e794
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Showing 8 changed files with 44 additions and 24 deletions.
diff --git a/common/acpi.c b/common/acpi.c
@@ -221,7 +221,7 @@ static const char *madt_int_trigger_names[] = {
     [ACPI_MADT_INT_TRIGGER_LT] = "Level",
 };
 
-static int process_madt_entries(void) {
+static int process_madt_entries(unsigned bsp_cpu_id) {
     acpi_madt_t *madt = (acpi_madt_t *) acpi_find_table(MADT_SIGNATURE);
     acpi_madt_entry_t *entry;
     bus_t *isa_bus;
@@ -246,11 +246,10 @@ static int process_madt_entries(void) {
             acpi_madt_processor_t *madt_cpu = (acpi_madt_processor_t *) entry->data;
             percpu_t *percpu = get_percpu_page(madt_cpu->apic_proc_id);
 
-            percpu->id = madt_cpu->apic_proc_id;
+            percpu->cpu_id = madt_cpu->apic_proc_id;
             percpu->apic_id = madt_cpu->apic_id;
-            percpu->enabled = madt_cpu->flags & 0x1;
-            if (madt_cpu->apic_proc_id == 0)
-                percpu->bsp = true;
+            percpu->bsp = !!(madt_cpu->apic_proc_id == bsp_cpu_id);
+            percpu->enabled = !!(madt_cpu->flags & 0x1);
 
             if (!percpu->enabled)
                 continue;
@@ -367,7 +366,7 @@ acpi_table_t *acpi_find_table(uint32_t signature) {
     return NULL;
 }
 
-int init_acpi(void) {
+int init_acpi(unsigned bsp_cpu_id) {
     unsigned acpi_nr_tables;
     rsdt_t *rsdt = NULL;
     xsdt_t *xsdt = NULL;
@@ -415,5 +414,5 @@ int init_acpi(void) {
     }
 
     acpi_dump_tables();
-    return process_madt_entries();
+    return process_madt_entries(bsp_cpu_id);
 }
diff --git a/common/percpu.c b/common/percpu.c
@@ -42,7 +42,7 @@ percpu_t *get_percpu_page(unsigned int cpu) {
     percpu_t *percpu;
 
     list_for_each_entry (percpu, &percpu_frames, list) {
-        if (percpu->id == cpu)
+        if (percpu->cpu_id == cpu)
             return percpu;
     }
 
@@ -52,7 +52,7 @@ percpu_t *get_percpu_page(unsigned int cpu) {
     percpu = get_free_page(GFP_IDENT | GFP_KERNEL);
     BUG_ON(!percpu);
 
-    percpu->id = cpu;
+    percpu->cpu_id = cpu;
     percpu->user_stack = get_free_page_top(GFP_USER);
 
     list_add(&percpu->list, &percpu_frames);

diff --git a/common/setup.c b/common/setup.c
@@ -55,9 +55,14 @@ bool_cmd("debug", opt_debug);
 
 io_port_t com_ports[2] = {COM1_PORT, COM2_PORT};
 
+static unsigned bsp_cpu_id = 0;
+
 const char *kernel_cmdline;
 char cpu_identifier[49];
 
+unsigned get_bsp_cpu_id(void) { return bsp_cpu_id; }
+void set_bsp_cpu_id(unsigned cpu_id) { bsp_cpu_id = cpu_id; }
+
 static __text_init int parse_bool(const char *s) {
     if (!strcmp("no", s) || !strcmp("off", s) || !strcmp("false", s) ||
         !strcmp("disable", s) || !strcmp("0", s))
@@ -208,11 +213,11 @@ void __noreturn __text_init kernel_start(uint32_t multiboot_magic,
 
     init_percpu();
 
-    init_traps(0);
+    init_traps(get_bsp_cpu_id());
 
     init_slab();
 
-    if (init_acpi() < 0 && init_mptables() < 0) {
+    if (init_acpi(get_bsp_cpu_id()) < 0 && init_mptables() < 0) {
         BUG();
     }
 
@@ -225,10 +230,10 @@ void __noreturn __text_init kernel_start(uint32_t multiboot_magic,
     init_ioapic();
 
     /* Initialize console input */
-    uart_input_init(0);
+    uart_input_init(get_bsp_cpu_id());
 
     /* Initialize Programmable Interrupt Timer */
-    init_pit(0);
+    init_pit(get_bsp_cpu_id());
 
     /* Jump from .text.init section to .text */
     asm volatile("push %0; ret" ::"r"(&kernel_main));

diff --git a/include/acpi.h b/include/acpi.h
@@ -249,6 +249,6 @@ typedef struct acpi_madt acpi_madt_t;
 extern acpi_table_t *acpi_find_table(uint32_t signature);
 
 extern unsigned acpi_get_nr_cpus(void);
-extern int init_acpi(void);
+extern int init_acpi(unsigned bsp_cpu_id);
 
 #endif /* KTF_ACPI_H */
diff --git a/include/percpu.h b/include/percpu.h
@@ -32,8 +32,14 @@
 
 struct percpu {
     list_head_t list;
-    unsigned int id : 8, apic_id : 8, enabled : 1, bsp : 1, family : 4, model : 4,
-        stepping : 4;
+
+    unsigned int cpu_id;
+    uint32_t apic_id;
+    bool enabled;
+    bool bsp;
+    uint8_t family;
+    uint8_t model;
+    uint8_t stepping;
 
     idt_entry_t *idt __aligned(16);
     idt_ptr_t idt_ptr;

diff --git a/include/setup.h b/include/setup.h
@@ -40,6 +40,8 @@ extern io_port_t com_ports[2];
 extern const char *kernel_cmdline;
 extern char cpu_identifier[49];
 
+/* Static declarations */
+
 static inline void get_com_ports(void) {
     memcpy((void *) com_ports, (void *) (BDA_COM_PORTS_ENTRY), sizeof(com_ports));
 
@@ -50,6 +52,11 @@ static inline void get_com_ports(void) {
         com_ports[1] = COM2_PORT;
 }
 
+/* External declarations */
+
+extern unsigned get_bsp_cpu_id(void);
+extern void set_bsp_cpu_id(unsigned cpu_id);
+
 extern void zap_boot_mappings(void);
 
 #endif /* __ASSEMBLY__ */

diff --git a/smp/mptables.c b/smp/mptables.c
@@ -210,12 +210,15 @@ static void process_mpc_entries(mpc_hdr_t *mpc_ptr) {
             percpu_t *percpu = get_percpu_page(nr_cpus++);
 
             percpu->apic_id = mpc_cpu->lapic_id;
-            percpu->enabled = mpc_cpu->en;
-            percpu->bsp = mpc_cpu->bsp;
+            percpu->enabled = !!mpc_cpu->en;
+            percpu->bsp = !!mpc_cpu->bsp;
             percpu->family = mpc_cpu->family;
             percpu->model = mpc_cpu->model;
             percpu->stepping = mpc_cpu->stepping;
 
+            if (percpu->bsp)
+                set_bsp_cpu_id(percpu->cpu_id);
+
             dump_mpc_processor_entry(mpc_cpu);
             entry_ptr += sizeof(*mpc_cpu);
             break;

diff --git a/smp/smp.c b/smp/smp.c
@@ -94,13 +94,13 @@ static __text_init void boot_cpu(unsigned int cpu) {
 }
 
 void __text_init init_smp(void) {
-    unsigned mp_nr_cpus = mptables_get_nr_cpus();
-    unsigned acpi_nr_cpus = acpi_get_nr_cpus();
-
-    nr_cpus = acpi_nr_cpus ?: mp_nr_cpus;
+    nr_cpus = acpi_get_nr_cpus();
     if (nr_cpus == 0) {
-        nr_cpus++;
-        return;
+        nr_cpus = mptables_get_nr_cpus();
+        if (nr_cpus == 0) {
+            nr_cpus++;
+            return;
+        }
     }
 
     printk("Initializing SMP support (CPUs: %u)\n", nr_cpus);