setjmp/longjmp hooks for kgdb 2.0.2

Hello. I'm currently starting down the road to adding PPC32 support to kgdb 2.0.x. The first patch I've got for you adds in hooks to allow for doing setjmp/longjmp, if the arch wants to do so. This isn't tested, yet (I haven't gotten that far in fixing ppc32 backend bits) but should be OK. Comments?

===== include/linux/kgdb.h 1.1 vs edited =====

include/linux/kgdb.h +4 -0

@@ -81,6 +81,10 @@
 	int  (*remove_break) (unsigned long addr, int type);
 	void (*correct_hw_break) (void);
 	void (*handler_exit) (void);
+	void (*setjmp) (long *buf);
+	void (*longjmp) (long *buf, int val);
+	void (*clearjmp) (void);
+	int  (*issetjmp) (void);
 	void (*shadowinfo)(struct pt_regs *regs, char *buffer, unsigned
 threadid); struct task_struct *(*get_shadow_thread)(struct pt_regs *regs,

int threadid); struct pt_regs *(*shadow_regs)(struct pt_regs *regs, int threadid); ===== kernel/kgdbstub.c 1.1 vs edited =====

kernel/kgdbstub.c +26 -0

@@ -72,6 +72,7 @@
 int kgdb_initialized = 0;
 int kgdb_enter = 0;
 static const char hexchars[] = "0123456789abcdef";
+static u_int fault_jmp_buf[100];
 
 int get_char(char *addr, unsigned char *data, int can_fault);
 int set_char(char *addr, int data, int can_fault);

@@ -255,6 +256,9 @@
 	int i;
 	unsigned char ch;
 
+	if (kgdb_ops->setjmp)
+		kgdb_ops->setjmp((long *)fault_jmp_buf);
+
 	for (i = 0; i < count; i++) {
 
 		if (get_char(mem++, &ch, can_fault) < 0)

@@ -263,6 +267,10 @@
 		*buf++ = hexchars[ch >> 4];
 		*buf++ = hexchars[ch % 16];
 	}
+
+	if (kgdb_ops->clearjmp)
+		kgdb_ops->clearjmp();
+
 	*buf = 0;
 	return (buf);
 }

@@ -275,12 +283,19 @@
 	int i;
 	unsigned char ch;
 
+	if (kgdb_ops->setjmp)
+		kgdb_ops->setjmp((long *)fault_jmp_buf);
+
 	for (i = 0; i < count; i++) {
 		ch = hex(*buf++) << 4;
 		ch = ch + hex(*buf++);
 		if (set_char(mem++, ch, can_fault) < 0)
 			break;
 	}
+
+	if (kgdb_ops->clearjmp)
+		kgdb_ops->clearjmp();
+
 	return (mem);
 }
 

@@ -295,6 +310,9 @@
 
 	*longValue = 0;
 
+	if (kgdb_ops->setjmp)
+		kgdb_ops->setjmp((long *)fault_jmp_buf);
+
 	while (**ptr) {
 		hexValue = hex(**ptr);
 		if (hexValue >= 0) {

@@ -306,6 +324,9 @@
 		(*ptr)++;
 	}
 
+	if (kgdb_ops->clearjmp)
+		kgdb_ops->clearjmp();
+
 	return (numChars);
 }
 

@@ -579,6 +600,11 @@
 	static char tmpstr[256];
 	int numshadowth = num_online_cpus() + kgdb_ops->shadowth;
 	int kgdb_usethreadid = 0;
+
+	if (kgdb_ops->issetjmp && kgdb_ops->issetjmp()) {
+		kgdb_ops->longjmp((long*)fault_jmp_buf, 1);
+		panic("longjmp failed!");
+	}
 
 	/*
 	 * Interrupts will be restored by the 'trap return' code, except when

Also, how should I send a patch that touches both things in the core, i386 and x86_64 patches (# HW breakpoints is arch-dependant.) ? Thanks.

Hi Tom,

It's nice to see someone working on integrating powerpc kgdb with mainline kgdb. There are a lot of features (like thread lists, gdb deatch-reattach, automodule loading) powerpc kgdb will inherit automatically from common core.

setjmp, longjmp isn't required. search_exception_tables take care of invalid memory accesses by kgdb.

In arch/ppc/mm/fault.c:do_page_fault, call bad_page_fault if debugger_memerr_expected is non-zero instead of holding mmap_sem.

bad_page_fault calls search_exception_tables at the begining. It takes care of invalid memory addresses by kgdb as kgdb uses get_user, put_user to access memory when the access can fail.

For powerpc arch specific code (like entry.S) look at
http://kgdb.sourceforge.net/linux-2.4.23-kgdb-1.9.patch
It contains powerpc arch specific code for kgdb. I was never able to test this code, so I don't know whether it works.

If you modify kgdb core as well as arch specific files, please try to send separate patches. Single patch will require me to do more work when I merge it against separate patches.

Quoted 10 lines · Amit S. Kale

Hi Tom,

It's nice to see someone working on integrating powerpc kgdb with mainline kgdb. There are a lot of features (like thread lists, gdb deatch-reattach, automodule loading) powerpc kgdb will inherit automatically from common core.

setjmp, longjmp isn't required. search_exception_tables take care of invalid memory accesses by kgdb.

Quoted 6 lines

In arch/ppc/mm/fault.c:do_page_fault, call bad_page_fault if debugger_memerr_expected is non-zero instead of holding mmap_sem.

bad_page_fault calls search_exception_tables at the begining. It takes care of invalid memory addresses by kgdb as kgdb uses get_user, put_user to access memory when the access can fail.

OK, thanks.

Quoted 4 lines

For powerpc arch specific code (like entry.S) look at
http://kgdb.sourceforge.net/linux-2.4.23-kgdb-1.9.patch
It contains powerpc arch specific code for kgdb. I was never able to test this code, so I don't know whether it works.

It might work on some subset of machines, but the serial driver is still broken for SERIAL_IO_MEM machines (which there are a lot of) nor is the ppc 8xx (which is what I would assume TimeSys used) serial driver patched up.

Quoted 3 lines

If you modify kgdb core as well as arch specific files, please try to send separate patches. Single patch will require me to do more work when I merge it against separate patches.

OK. I _hope_ to get you a patch for the serial stuff shortly.

Quoted 25 lines · Tom Rini

Quoted 10 lines · Amit S. Kale

Hi Tom,

It's nice to see someone working on integrating powerpc kgdb with mainline kgdb. There are a lot of features (like thread lists, gdb deatch-reattach, automodule loading) powerpc kgdb will inherit automatically from common core.

setjmp, longjmp isn't required. search_exception_tables take care of invalid memory accesses by kgdb.

Quoted 6 lines

In arch/ppc/mm/fault.c:do_page_fault, call bad_page_fault if debugger_memerr_expected is non-zero instead of holding mmap_sem.

bad_page_fault calls search_exception_tables at the begining. It takes care of invalid memory addresses by kgdb as kgdb uses get_user, put_user to access memory when the access can fail.

OK, thanks.

Quoted 4 lines

For powerpc arch specific code (like entry.S) look at
http://kgdb.sourceforge.net/linux-2.4.23-kgdb-1.9.patch
It contains powerpc arch specific code for kgdb. I was never able to test this code, so I don't know whether it works.

Quoted 4 lines

It might work on some subset of machines, but the serial driver is still broken for SERIAL_IO_MEM machines (which there are a lot of) nor is the ppc 8xx (which is what I would assume TimeSys used) serial driver patched up.

Yes. There is a lot of #ifdef CONFIG_KGDB code in their arch/ppc/8260_io/uart.c If your ppc machine uses the same uart, please let me know and I'll send you this file.

Which test machine do you have?