Changeset 65f3117 in mainline for kernel/generic/src/main/main.c

Timestamp:

2023-02-25T13:16:38Z (14 months ago)

Author:

Jiří Zárevúcky <zarevucky.jiri@…>

Branches:

master, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

6188fee

Parents:

4f84ee42

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2023-02-14 13:38:14)

git-committer:

Jiří Zárevúcky <zarevucky.jiri@…> (2023-02-25 13:16:38)

Message:

Make bootstrap stack statically, rather than dynamically allocated

With aligment requirements being part of the language now, it is
simple to allocate the extra stack area in kernel data, and we
don't need to go to so much trouble with manual allocation.
It also makes it slightly more straightforward to use the stack
from assembly, without having to dig through a saved context
structure.

File:

• kernel/generic/src/main/main.c (modified) (2 diffs)

kernel/generic/src/main/main.c

@@ -137 +137 @@
 uintptr_t stack_safe = 0;
 
+// NOTE: All kernel stacks must be aligned to STACK_SIZE, see CURRENT.
+const size_t bootstrap_stack_size = STACK_SIZE;
+_Alignas(STACK_SIZE) uint8_t bootstrap_stack[STACK_SIZE];
+/* Just a convenient value for some assembly code. */
+const uint8_t *bootstrap_stack_top = bootstrap_stack + STACK_SIZE;
+
 /*
  * These two functions prevent stack from underflowing during the
@@ -170 +176 @@
             ALIGN_UP((uintptr_t) kdata_end - config.base, PAGE_SIZE);
 
-        /*
-         * NOTE: All kernel stacks must be aligned to STACK_SIZE,
-         *       see CURRENT.
-         */
-
-        /* Place the stack after the kernel, init and ballocs. */
-        config.stack_base =
-            ALIGN_UP(config.base + config.kernel_size, STACK_SIZE);
-        config.stack_size = STACK_SIZE;
-
-        /* Avoid placing stack on top of init */
-        size_t i;
-        for (i = 0; i < init.cnt; i++) {
-                uintptr_t p = init.tasks[i].paddr + init.tasks[i].size;
-                uintptr_t bottom = PA2KA(ALIGN_UP(p, STACK_SIZE));
-
-                if (config.stack_base < bottom)
-                        config.stack_base = bottom;
-        }
-
-        /* Avoid placing stack on top of boot allocations. */
-        if (ballocs.size) {
-                uintptr_t bottom =
-                    ALIGN_UP(ballocs.base + ballocs.size, STACK_SIZE);
-                if (config.stack_base < bottom)
-                        config.stack_base = bottom;
-        }
-
-        if (config.stack_base < stack_safe)
-                config.stack_base = ALIGN_UP(stack_safe, STACK_SIZE);
-
         context_save(&ctx);
         context_set(&ctx, FADDR(main_bsp_separated_stack),
-            config.stack_base, STACK_SIZE);
+            bootstrap_stack, bootstrap_stack_size);
         context_restore(&ctx);
         /* not reached */