Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 150 insertions, 0 deletions

diff --git a/arch/ia64/oprofile/backtrace.c b/arch/ia64/oprofile/backtrace.c
new file mode 100644
index 000000000000..b7dabbfb0d61
--- /dev/null
+++ b/arch/ia64/oprofile/backtrace.c
@@ -0,0 +1,150 @@
+/**
+ * @file backtrace.c
+ *
+ * @remark Copyright 2004 Silicon Graphics Inc.  All Rights Reserved.
+ * @remark Read the file COPYING
+ *
+ * @author Greg Banks <gnb@melbourne.sgi.com>
+ * @author Keith Owens <kaos@melbourne.sgi.com>
+ * Based on work done for the ia64 port of the SGI kernprof patch, which is
+ *    Copyright (c) 2003-2004 Silicon Graphics Inc.  All Rights Reserved.
+ */
+
+#include <linux/oprofile.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <asm/ptrace.h>
+#include <asm/system.h>
+
+/*
+ * For IA64 we need to perform a complex little dance to get both
+ * the struct pt_regs and a synthetic struct switch_stack in place
+ * to allow the unwind code to work.  This dance requires our unwind
+ * using code to be called from a function called from unw_init_running().
+ * There we only get a single void* data pointer, so use this struct
+ * to hold all the data we need during the unwind.
+ */
+typedef struct
+{
+        unsigned int depth;
+        struct pt_regs *regs;
+        struct unw_frame_info frame;
+        u64 *prev_pfs_loc;      /* state for WAR for old spinlock ool code */
+} ia64_backtrace_t;
+
+#if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 3)
+/*
+ * Returns non-zero if the PC is in the spinlock contention out-of-line code
+ * with non-standard calling sequence (on older compilers).
+ */
+static __inline__ int in_old_ool_spinlock_code(unsigned long pc)
+{
+        extern const char ia64_spinlock_contention_pre3_4[] __attribute__ ((weak));
+        extern const char ia64_spinlock_contention_pre3_4_end[] __attribute__ ((weak));
+        unsigned long sc_start = (unsigned long)ia64_spinlock_contention_pre3_4;
+        unsigned long sc_end = (unsigned long)ia64_spinlock_contention_pre3_4_end;
+        return (sc_start && sc_end && pc >= sc_start && pc < sc_end);
+}
+#else
+/* Newer spinlock code does a proper br.call and works fine with the unwinder */
+#define in_old_ool_spinlock_code(pc)    0
+#endif
+
+/* Returns non-zero if the PC is in the Interrupt Vector Table */
+static __inline__ int in_ivt_code(unsigned long pc)
+{
+        extern char ia64_ivt[];
+        return (pc >= (u_long)ia64_ivt && pc < (u_long)ia64_ivt+32768);
+}
+
+/*
+ * Unwind to next stack frame.
+ */
+static __inline__ int next_frame(ia64_backtrace_t *bt)
+{
+        /*
+         * Avoid unsightly console message from unw_unwind() when attempting
+         * to unwind through the Interrupt Vector Table which has no unwind
+         * information.
+         */
+        if (in_ivt_code(bt->frame.ip))
+                return 0;
+
+        /*
+         * WAR for spinlock contention from leaf functions.  ia64_spinlock_contention_pre3_4
+         * has ar.pfs == r0.  Leaf functions do not modify ar.pfs so ar.pfs remains
+         * as 0, stopping the backtrace.  Record the previous ar.pfs when the current
+         * IP is in ia64_spinlock_contention_pre3_4 then unwind, if pfs_loc has not changed
+         * after unwind then use pt_regs.ar_pfs which is where the real ar.pfs is for
+         * leaf functions.
+         */
+        if (bt->prev_pfs_loc && bt->regs && bt->frame.pfs_loc == bt->prev_pfs_loc)
+                bt->frame.pfs_loc = &bt->regs->ar_pfs;
+        bt->prev_pfs_loc = (in_old_ool_spinlock_code(bt->frame.ip) ? bt->frame.pfs_loc : NULL);
+
+        return unw_unwind(&bt->frame) == 0;
+}
+
+
+static void do_ia64_backtrace(struct unw_frame_info *info, void *vdata)
+{
+        ia64_backtrace_t *bt = vdata;
+        struct switch_stack *sw;
+        int count = 0;
+        u_long pc, sp;
+
+        sw = (struct switch_stack *)(info+1);
+        /* padding from unw_init_running */
+        sw = (struct switch_stack *)(((unsigned long)sw + 15) & ~15);
+
+        unw_init_frame_info(&bt->frame, current, sw);
+
+        /* skip over interrupt frame and oprofile calls */
+        do {
+                unw_get_sp(&bt->frame, &sp);
+                if (sp >= (u_long)bt->regs)
+                        break;
+                if (!next_frame(bt))
+                        return;
+        } while (count++ < 200);
+
+        /* finally, grab the actual sample */
+        while (bt->depth-- && next_frame(bt)) {
+                unw_get_ip(&bt->frame, &pc);
+                oprofile_add_trace(pc);
+                if (unw_is_intr_frame(&bt->frame)) {
+                        /*
+                         * Interrupt received on kernel stack; this can
+                         * happen when timer interrupt fires while processing
+                         * a softirq from the tail end of a hardware interrupt
+                         * which interrupted a system call.  Don't laugh, it
+                         * happens!  Splice the backtrace into two parts to
+                         * avoid spurious cycles in the gprof output.
+                         */
+                        /* TODO: split rather than drop the 2nd half */
+                        break;
+                }
+        }
+}
+
+void
+ia64_backtrace(struct pt_regs * const regs, unsigned int depth)
+{
+        ia64_backtrace_t bt;
+        unsigned long flags;
+
+        /*
+         * On IA64 there is little hope of getting backtraces from
+         * user space programs -- the problems of getting the unwind
+         * information from arbitrary user programs are extreme.
+         */
+        if (user_mode(regs))
+                return;
+
+        bt.depth = depth;
+        bt.regs = regs;
+        bt.prev_pfs_loc = NULL;
+        local_irq_save(flags);
+        unw_init_running(do_ia64_backtrace, &bt);
+        local_irq_restore(flags);
+}