- Introduce kernel_kseg0_end variable that marks first address in KSEG0

    available for use. All data below this address considered to be used
    by kernel. Along with kernel own data it might be symbol tables
    prepeared by trampoline code, boot loader service data passed for
    further analysis by kernel, etc... By default kernel_kseg0_end points
    to the end of loaded kernel.

- Introduce mips_postboot_fixup function. It checks for symbol information
    copied by ELF trampoline and passes it to KDB

2 files changed, 35 insertions, 0 deletions

diff --git a/sys/mips/include/md_var.h b/sys/mips/include/md_var.h
index dbfb45157f74..ab3c3e6cf723 100644
--- a/sys/mips/include/md_var.h
+++ b/sys/mips/include/md_var.h
@@ -44,6 +44,7 @@ extern	char	sigcode[];
 extern	int	szsigcode, szosigcode;
 
 extern vm_offset_t kstack0;
+extern vm_offset_t kernel_kseg0_end;
 
 void	MipsSaveCurFPState(struct thread *);
 void	fork_trampoline(void);
@@ -69,6 +70,7 @@ void	cpu_identify(void);
 void	mips_cpu_init(void);
 void	mips_pcpu0_init(void);
 void	mips_proc0_init(void);
+void	mips_postboot_fixup(void);
 
 /* Platform call-downs. */
 void	platform_identify(void);
diff --git a/sys/mips/mips/machdep.c b/sys/mips/mips/machdep.c
index d31ffce03750..029c3dcee2bc 100644
--- a/sys/mips/mips/machdep.c
+++ b/sys/mips/mips/machdep.c
@@ -85,6 +85,7 @@ __FBSDID("$FreeBSD$");
 #include <machine/clock.h>
 #include <machine/cpu.h>
 #include <machine/cpuregs.h>
+#include <machine/elf.h>
 #include <machine/hwfunc.h>
 #include <machine/intr_machdep.h>
 #include <machine/md_var.h>
@@ -151,9 +152,18 @@ extern char MipsTLBMiss[], MipsTLBMissEnd[];
 extern char MipsCache[], MipsCacheEnd[];
 
 extern char edata[], end[];
+#ifdef DDB
+extern vm_offset_t ksym_start, ksym_end;
+#endif
 
 u_int32_t bootdev;
 struct bootinfo bootinfo;
+/*
+ * First kseg0 address available for use. By default it's equal to &end.
+ * But in some cases there might be additional data placed right after 
+ * _end by loader or ELF trampoline.
+ */
+vm_offset_t kernel_kseg0_end = (vm_offset_t)&end;
 
 static void
 cpu_startup(void *dummy)
@@ -360,6 +370,29 @@ mips_vector_init(void)
 }
 
 /*
+ * Fix kernel_kseg0_end address in case trampoline placed debug sympols 
+ * data there
+ */
+void
+mips_postboot_fixup(void)
+{
+#ifdef DDB
+	Elf_Size *trampoline_data = (Elf_Size*)kernel_kseg0_end;
+	Elf_Size symtabsize = 0;
+
+	if (trampoline_data[0] == SYMTAB_MAGIC) {
+		symtabsize = trampoline_data[1];
+		kernel_kseg0_end += 2 * sizeof(Elf_Size);
+		/* start of .symtab */
+		ksym_start = kernel_kseg0_end;
+		kernel_kseg0_end += symtabsize;
+		/* end of .strtab */
+		ksym_end = kernel_kseg0_end;
+	}
+#endif
+}
+
+/*
  * Many SoCs have a means to reset the core itself.  Others do not, or
  * the method is unknown to us.  For those cases, we jump to the mips
  * reset vector and hope for the best.  This works well in practice.