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Diffstat (limited to 'src/stacks.c')
-rw-r--r--src/stacks.c237
1 files changed, 140 insertions, 97 deletions
diff --git a/src/stacks.c b/src/stacks.c
index 48512b0..da5daa9 100644
--- a/src/stacks.c
+++ b/src/stacks.c
@@ -8,20 +8,44 @@
#include "util.h" // dprintf
#include "bregs.h" // CR0_PE
-// Thread info - stored at bottom of each thread stack - don't change
-// without also updating the inline assembler below.
-struct thread_info {
- struct thread_info *next;
- void *stackpos;
- struct thread_info **pprev;
-};
-struct thread_info VAR32FLATVISIBLE MainThread = {
- &MainThread, NULL, &MainThread.next
-};
+
+/****************************************************************
+ * Extra 16bit stack
+ ****************************************************************/
+
+// Space for a stack for 16bit code.
+u8 ExtraStack[BUILD_EXTRA_STACK_SIZE+1] VARLOW __aligned(8);
+
+// Switch to the extra stack and call a function.
+inline u32
+stack_hop(u32 eax, u32 edx, void *func)
+{
+ ASSERT16();
+ u16 stack_seg = SEG_LOW, bkup_ss;
+ u32 bkup_esp;
+ asm volatile(
+ // Backup current %ss/%esp values.
+ "movw %%ss, %w3\n"
+ "movl %%esp, %4\n"
+ // Copy stack seg to %ds/%ss and set %esp
+ "movw %w6, %%ds\n"
+ "movw %w6, %%ss\n"
+ "movl %5, %%esp\n"
+ // Call func
+ "calll *%2\n"
+ // Restore segments and stack
+ "movw %w3, %%ds\n"
+ "movw %w3, %%ss\n"
+ "movl %4, %%esp"
+ : "+a" (eax), "+d" (edx), "+c" (func), "=&r" (bkup_ss), "=&r" (bkup_esp)
+ : "i" (&ExtraStack[BUILD_EXTRA_STACK_SIZE]), "r" (stack_seg)
+ : "cc", "memory");
+ return eax;
+}
/****************************************************************
- * Low level helpers
+ * 16bit / 32bit calling
****************************************************************/
static inline void sgdt(struct descloc_s *desc) {
@@ -88,98 +112,48 @@ call32(void *func, u32 eax, u32 errret)
return eax;
}
-// 16bit trampoline for enabling irqs from 32bit mode.
-ASM16(
- " .global trampoline_checkirqs\n"
- "trampoline_checkirqs:\n"
- " rep ; nop\n"
- " lretw"
- );
-
-static void
-check_irqs(void)
+// Call a function with a specified register state. Note that on
+// return, the interrupt enable/disable flag may be altered.
+inline void
+farcall16(struct bregs *callregs)
{
- if (MODESEGMENT) {
- asm volatile(
- "sti\n"
- "nop\n"
- "rep ; nop\n"
- "cli\n"
- "cld\n"
- : : :"memory");
- return;
- }
- extern void trampoline_checkirqs();
- struct bregs br;
- br.flags = F_IF;
- br.code.seg = SEG_BIOS;
- br.code.offset = (u32)&trampoline_checkirqs;
- farcall16big(&br);
+ if (!MODESEGMENT && getesp() > BUILD_STACK_ADDR)
+ panic("call16 with invalid stack\n");
+ asm volatile(
+#if MODE16 == 1
+ "calll __farcall16\n"
+ "cli\n"
+ "cld"
+#else
+ "calll __farcall16_from32"
+#endif
+ : "+a" (callregs), "+m" (*callregs)
+ :
+ : "ebx", "ecx", "edx", "esi", "edi", "cc", "memory");
}
-// 16bit trampoline for waiting for an irq from 32bit mode.
-ASM16(
- " .global trampoline_waitirq\n"
- "trampoline_waitirq:\n"
- " sti\n"
- " hlt\n"
- " lretw"
- );
-
-// Wait for next irq to occur.
-void
-yield_toirq(void)
+inline void
+farcall16big(struct bregs *callregs)
{
- if (MODESEGMENT) {
- asm volatile("sti ; hlt ; cli ; cld": : :"memory");
- return;
- }
- if (CONFIG_THREADS && MainThread.next != &MainThread) {
- // Threads still active - do a yield instead.
- yield();
- return;
- }
- extern void trampoline_waitirq();
- struct bregs br;
- br.flags = 0;
- br.code.seg = SEG_BIOS;
- br.code.offset = (u32)&trampoline_waitirq;
- farcall16big(&br);
+ ASSERT32FLAT();
+ if (getesp() > BUILD_STACK_ADDR)
+ panic("call16 with invalid stack\n");
+ asm volatile(
+ "calll __farcall16big_from32"
+ : "+a" (callregs), "+m" (*callregs)
+ :
+ : "ebx", "ecx", "edx", "esi", "edi", "cc", "memory");
}
-
-/****************************************************************
- * Extra 16bit stack
- ****************************************************************/
-
-// Space for a stack for 16bit code.
-u8 ExtraStack[BUILD_EXTRA_STACK_SIZE+1] VARLOW __aligned(8);
-
-// Switch to the extra stack and call a function.
-inline u32
-stack_hop(u32 eax, u32 edx, void *func)
+inline void
+__call16_int(struct bregs *callregs, u16 offset)
{
- ASSERT16();
- u16 stack_seg = SEG_LOW, bkup_ss;
- u32 bkup_esp;
- asm volatile(
- // Backup current %ss/%esp values.
- "movw %%ss, %w3\n"
- "movl %%esp, %4\n"
- // Copy stack seg to %ds/%ss and set %esp
- "movw %w6, %%ds\n"
- "movw %w6, %%ss\n"
- "movl %5, %%esp\n"
- // Call func
- "calll *%2\n"
- // Restore segments and stack
- "movw %w3, %%ds\n"
- "movw %w3, %%ss\n"
- "movl %4, %%esp"
- : "+a" (eax), "+d" (edx), "+c" (func), "=&r" (bkup_ss), "=&r" (bkup_esp)
- : "i" (&ExtraStack[BUILD_EXTRA_STACK_SIZE]), "r" (stack_seg)
- : "cc", "memory");
- return eax;
+ if (MODESEGMENT)
+ callregs->code.seg = GET_SEG(CS);
+ else
+ callregs->code.seg = SEG_BIOS;
+ callregs->code.offset = offset;
+ farcall16(callregs);
}
@@ -187,8 +161,17 @@ stack_hop(u32 eax, u32 edx, void *func)
* Threads
****************************************************************/
+// Thread info - stored at bottom of each thread stack - don't change
+// without also updating the inline assembler below.
+struct thread_info {
+ struct thread_info *next;
+ void *stackpos;
+ struct thread_info **pprev;
+};
+struct thread_info VAR32FLATVISIBLE MainThread = {
+ &MainThread, NULL, &MainThread.next
+};
#define THREADSTACKSIZE 4096
-int VAR16VISIBLE CanPreempt;
// Return the 'struct thread_info' for the currently running thread.
struct thread_info *
@@ -221,6 +204,35 @@ switch_next(struct thread_info *cur)
: "ebx", "edx", "esi", "edi", "cc", "memory");
}
+// 16bit trampoline for enabling irqs from 32bit mode.
+ASM16(
+ " .global trampoline_checkirqs\n"
+ "trampoline_checkirqs:\n"
+ " rep ; nop\n"
+ " lretw"
+ );
+
+static void
+check_irqs(void)
+{
+ if (MODESEGMENT) {
+ asm volatile(
+ "sti\n"
+ "nop\n"
+ "rep ; nop\n"
+ "cli\n"
+ "cld\n"
+ : : :"memory");
+ return;
+ }
+ extern void trampoline_checkirqs();
+ struct bregs br;
+ br.flags = F_IF;
+ br.code.seg = SEG_BIOS;
+ br.code.offset = (u32)&trampoline_checkirqs;
+ farcall16big(&br);
+}
+
// Briefly permit irqs to occur.
void
yield(void)
@@ -239,6 +251,36 @@ yield(void)
switch_next(cur);
}
+// 16bit trampoline for waiting for an irq from 32bit mode.
+ASM16(
+ " .global trampoline_waitirq\n"
+ "trampoline_waitirq:\n"
+ " sti\n"
+ " hlt\n"
+ " lretw"
+ );
+
+// Wait for next irq to occur.
+void
+yield_toirq(void)
+{
+ if (MODESEGMENT) {
+ asm volatile("sti ; hlt ; cli ; cld": : :"memory");
+ return;
+ }
+ if (CONFIG_THREADS && MainThread.next != &MainThread) {
+ // Threads still active - do a yield instead.
+ yield();
+ return;
+ }
+ extern void trampoline_waitirq();
+ struct bregs br;
+ br.flags = 0;
+ br.code.seg = SEG_BIOS;
+ br.code.offset = (u32)&trampoline_waitirq;
+ farcall16big(&br);
+}
+
// Last thing called from a thread (called on "next" stack).
static void
__end_thread(struct thread_info *old)
@@ -332,6 +374,7 @@ mutex_unlock(struct mutex_s *mutex)
* Thread preemption
****************************************************************/
+int VAR16VISIBLE CanPreempt;
static u32 PreemptCount;
// Turn on RTC irqs and arrange for them to check the 32bit threads.
generated by cgit v1.1 at 2024-11-20 18:33:05 +0000