powerpc/perf: Move perf core & PMU code into a subdirectory

The perf code has grown a lot since it started, and is big enough to
warrant its own subdirectory. For reference it's ~60% bigger than the
oprofile code. It declutters the kernel directory, makes it simpler to
grep for "just perf stuff", and allows us to shorten some filenames.

While we're at it, make it more obvious that we have two implementations
of the core perf logic. One for (roughly) Book3S CPUs, which was the
original implementation, and the other for Freescale embedded CPUs.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 492 insertions, 0 deletions

diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
new file mode 100644
index 00000000000..e8a18d1cc7c
--- /dev/null
+++ b/arch/powerpc/perf/callchain.c
@@ -0,0 +1,492 @@
+/*
+ * Performance counter callchain support - powerpc architecture code
+ *
+ * Copyright © 2009 Paul Mackerras, IBM Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/perf_event.h>
+#include <linux/percpu.h>
+#include <linux/uaccess.h>
+#include <linux/mm.h>
+#include <asm/ptrace.h>
+#include <asm/pgtable.h>
+#include <asm/sigcontext.h>
+#include <asm/ucontext.h>
+#include <asm/vdso.h>
+#ifdef CONFIG_PPC64
+#include "../kernel/ppc32.h"
+#endif
+
+
+/*
+ * Is sp valid as the address of the next kernel stack frame after prev_sp?
+ * The next frame may be in a different stack area but should not go
+ * back down in the same stack area.
+ */
+static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
+{
+        if (sp & 0xf)
+                return 0;               /* must be 16-byte aligned */
+        if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
+                return 0;
+        if (sp >= prev_sp + STACK_FRAME_OVERHEAD)
+                return 1;
+        /*
+         * sp could decrease when we jump off an interrupt stack
+         * back to the regular process stack.
+         */
+        if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1)))
+                return 1;
+        return 0;
+}
+
+void
+perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
+{
+        unsigned long sp, next_sp;
+        unsigned long next_ip;
+        unsigned long lr;
+        long level = 0;
+        unsigned long *fp;
+
+        lr = regs->link;
+        sp = regs->gpr[1];
+        perf_callchain_store(entry, regs->nip);
+
+        if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
+                return;
+
+        for (;;) {
+                fp = (unsigned long *) sp;
+                next_sp = fp[0];
+
+                if (next_sp == sp + STACK_INT_FRAME_SIZE &&
+                    fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
+                        /*
+                         * This looks like an interrupt frame for an
+                         * interrupt that occurred in the kernel
+                         */
+                        regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD);
+                        next_ip = regs->nip;
+                        lr = regs->link;
+                        level = 0;
+                        perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
+
+                } else {
+                        if (level == 0)
+                                next_ip = lr;
+                        else
+                                next_ip = fp[STACK_FRAME_LR_SAVE];
+
+                        /*
+                         * We can't tell which of the first two addresses
+                         * we get are valid, but we can filter out the
+                         * obviously bogus ones here.  We replace them
+                         * with 0 rather than removing them entirely so
+                         * that userspace can tell which is which.
+                         */
+                        if ((level == 1 && next_ip == lr) ||
+                            (level <= 1 && !kernel_text_address(next_ip)))
+                                next_ip = 0;
+
+                        ++level;
+                }
+
+                perf_callchain_store(entry, next_ip);
+                if (!valid_next_sp(next_sp, sp))
+                        return;
+                sp = next_sp;
+        }
+}
+
+#ifdef CONFIG_PPC64
+/*
+ * On 64-bit we don't want to invoke hash_page on user addresses from
+ * interrupt context, so if the access faults, we read the page tables
+ * to find which page (if any) is mapped and access it directly.
+ */
+static int read_user_stack_slow(void __user *ptr, void *ret, int nb)
+{
+        pgd_t *pgdir;
+        pte_t *ptep, pte;
+        unsigned shift;
+        unsigned long addr = (unsigned long) ptr;
+        unsigned long offset;
+        unsigned long pfn;
+        void *kaddr;
+
+        pgdir = current->mm->pgd;
+        if (!pgdir)
+                return -EFAULT;
+
+        ptep = find_linux_pte_or_hugepte(pgdir, addr, &shift);
+        if (!shift)
+                shift = PAGE_SHIFT;
+
+        /* align address to page boundary */
+        offset = addr & ((1UL << shift) - 1);
+        addr -= offset;
+
+        if (ptep == NULL)
+                return -EFAULT;
+        pte = *ptep;
+        if (!pte_present(pte) || !(pte_val(pte) & _PAGE_USER))
+                return -EFAULT;
+        pfn = pte_pfn(pte);
+        if (!page_is_ram(pfn))
+                return -EFAULT;
+
+        /* no highmem to worry about here */
+        kaddr = pfn_to_kaddr(pfn);
+        memcpy(ret, kaddr + offset, nb);
+        return 0;
+}
+
+static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
+{
+        if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) ||
+            ((unsigned long)ptr & 7))
+                return -EFAULT;
+
+        pagefault_disable();
+        if (!__get_user_inatomic(*ret, ptr)) {
+                pagefault_enable();
+                return 0;
+        }
+        pagefault_enable();
+
+        return read_user_stack_slow(ptr, ret, 8);
+}
+
+static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
+{
+        if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
+            ((unsigned long)ptr & 3))
+                return -EFAULT;
+
+        pagefault_disable();
+        if (!__get_user_inatomic(*ret, ptr)) {
+                pagefault_enable();
+                return 0;
+        }
+        pagefault_enable();
+
+        return read_user_stack_slow(ptr, ret, 4);
+}
+
+static inline int valid_user_sp(unsigned long sp, int is_64)
+{
+        if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32)
+                return 0;
+        return 1;
+}
+
+/*
+ * 64-bit user processes use the same stack frame for RT and non-RT signals.
+ */
+struct signal_frame_64 {
+        char            dummy[__SIGNAL_FRAMESIZE];
+        struct ucontext uc;
+        unsigned long   unused[2];
+        unsigned int    tramp[6];
+        struct siginfo  *pinfo;
+        void            *puc;
+        struct siginfo  info;
+        char            abigap[288];
+};
+
+static int is_sigreturn_64_address(unsigned long nip, unsigned long fp)
+{
+        if (nip == fp + offsetof(struct signal_frame_64, tramp))
+                return 1;
+        if (vdso64_rt_sigtramp && current->mm->context.vdso_base &&
+            nip == current->mm->context.vdso_base + vdso64_rt_sigtramp)
+                return 1;
+        return 0;
+}
+
+/*
+ * Do some sanity checking on the signal frame pointed to by sp.
+ * We check the pinfo and puc pointers in the frame.
+ */
+static int sane_signal_64_frame(unsigned long sp)
+{
+        struct signal_frame_64 __user *sf;
+        unsigned long pinfo, puc;
+
+        sf = (struct signal_frame_64 __user *) sp;
+        if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) ||
+            read_user_stack_64((unsigned long __user *) &sf->puc, &puc))
+                return 0;
+        return pinfo == (unsigned long) &sf->info &&
+                puc == (unsigned long) &sf->uc;
+}
+
+static void perf_callchain_user_64(struct perf_callchain_entry *entry,
+                                   struct pt_regs *regs)
+{
+        unsigned long sp, next_sp;
+        unsigned long next_ip;
+        unsigned long lr;
+        long level = 0;
+        struct signal_frame_64 __user *sigframe;
+        unsigned long __user *fp, *uregs;
+
+        next_ip = regs->nip;
+        lr = regs->link;
+        sp = regs->gpr[1];
+        perf_callchain_store(entry, next_ip);
+
+        for (;;) {
+                fp = (unsigned long __user *) sp;
+                if (!valid_user_sp(sp, 1) || read_user_stack_64(fp, &next_sp))
+                        return;
+                if (level > 0 && read_user_stack_64(&fp[2], &next_ip))
+                        return;
+
+                /*
+                 * Note: the next_sp - sp >= signal frame size check
+                 * is true when next_sp < sp, which can happen when
+                 * transitioning from an alternate signal stack to the
+                 * normal stack.
+                 */
+                if (next_sp - sp >= sizeof(struct signal_frame_64) &&
+                    (is_sigreturn_64_address(next_ip, sp) ||
+                     (level <= 1 && is_sigreturn_64_address(lr, sp))) &&
+                    sane_signal_64_frame(sp)) {
+                        /*
+                         * This looks like an signal frame
+                         */
+                        sigframe = (struct signal_frame_64 __user *) sp;
+                        uregs = sigframe->uc.uc_mcontext.gp_regs;
+                        if (read_user_stack_64(&uregs[PT_NIP], &next_ip) ||
+                            read_user_stack_64(&uregs[PT_LNK], &lr) ||
+                            read_user_stack_64(&uregs[PT_R1], &sp))
+                                return;
+                        level = 0;
+                        perf_callchain_store(entry, PERF_CONTEXT_USER);
+                        perf_callchain_store(entry, next_ip);
+                        continue;
+                }
+
+                if (level == 0)
+                        next_ip = lr;
+                perf_callchain_store(entry, next_ip);
+                ++level;
+                sp = next_sp;
+        }
+}
+
+static inline int current_is_64bit(void)
+{
+        /*
+         * We can't use test_thread_flag() here because we may be on an
+         * interrupt stack, and the thread flags don't get copied over
+         * from the thread_info on the main stack to the interrupt stack.
+         */
+        return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT);
+}
+
+#else  /* CONFIG_PPC64 */
+/*
+ * On 32-bit we just access the address and let hash_page create a
+ * HPTE if necessary, so there is no need to fall back to reading
+ * the page tables.  Since this is called at interrupt level,
+ * do_page_fault() won't treat a DSI as a page fault.
+ */
+static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
+{
+        int rc;
+
+        if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
+            ((unsigned long)ptr & 3))
+                return -EFAULT;
+
+        pagefault_disable();
+        rc = __get_user_inatomic(*ret, ptr);
+        pagefault_enable();
+
+        return rc;
+}
+
+static inline void perf_callchain_user_64(struct perf_callchain_entry *entry,
+                                          struct pt_regs *regs)
+{
+}
+
+static inline int current_is_64bit(void)
+{
+        return 0;
+}
+
+static inline int valid_user_sp(unsigned long sp, int is_64)
+{
+        if (!sp || (sp & 7) || sp > TASK_SIZE - 32)
+                return 0;
+        return 1;
+}
+
+#define __SIGNAL_FRAMESIZE32    __SIGNAL_FRAMESIZE
+#define sigcontext32            sigcontext
+#define mcontext32              mcontext
+#define ucontext32              ucontext
+#define compat_siginfo_t        struct siginfo
+
+#endif /* CONFIG_PPC64 */
+
+/*
+ * Layout for non-RT signal frames
+ */
+struct signal_frame_32 {
+        char                    dummy[__SIGNAL_FRAMESIZE32];
+        struct sigcontext32     sctx;
+        struct mcontext32       mctx;
+        int                     abigap[56];
+};
+
+/*
+ * Layout for RT signal frames
+ */
+struct rt_signal_frame_32 {
+        char                    dummy[__SIGNAL_FRAMESIZE32 + 16];
+        compat_siginfo_t        info;
+        struct ucontext32       uc;
+        int                     abigap[56];
+};
+
+static int is_sigreturn_32_address(unsigned int nip, unsigned int fp)
+{
+        if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad))
+                return 1;
+        if (vdso32_sigtramp && current->mm->context.vdso_base &&
+            nip == current->mm->context.vdso_base + vdso32_sigtramp)
+                return 1;
+        return 0;
+}
+
+static int is_rt_sigreturn_32_address(unsigned int nip, unsigned int fp)
+{
+        if (nip == fp + offsetof(struct rt_signal_frame_32,
+                                 uc.uc_mcontext.mc_pad))
+                return 1;
+        if (vdso32_rt_sigtramp && current->mm->context.vdso_base &&
+            nip == current->mm->context.vdso_base + vdso32_rt_sigtramp)
+                return 1;
+        return 0;
+}
+
+static int sane_signal_32_frame(unsigned int sp)
+{
+        struct signal_frame_32 __user *sf;
+        unsigned int regs;
+
+        sf = (struct signal_frame_32 __user *) (unsigned long) sp;
+        if (read_user_stack_32((unsigned int __user *) &sf->sctx.regs, &regs))
+                return 0;
+        return regs == (unsigned long) &sf->mctx;
+}
+
+static int sane_rt_signal_32_frame(unsigned int sp)
+{
+        struct rt_signal_frame_32 __user *sf;
+        unsigned int regs;
+
+        sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
+        if (read_user_stack_32((unsigned int __user *) &sf->uc.uc_regs, &regs))
+                return 0;
+        return regs == (unsigned long) &sf->uc.uc_mcontext;
+}
+
+static unsigned int __user *signal_frame_32_regs(unsigned int sp,
+                                unsigned int next_sp, unsigned int next_ip)
+{
+        struct mcontext32 __user *mctx = NULL;
+        struct signal_frame_32 __user *sf;
+        struct rt_signal_frame_32 __user *rt_sf;
+
+        /*
+         * Note: the next_sp - sp >= signal frame size check
+         * is true when next_sp < sp, for example, when
+         * transitioning from an alternate signal stack to the
+         * normal stack.
+         */
+        if (next_sp - sp >= sizeof(struct signal_frame_32) &&
+            is_sigreturn_32_address(next_ip, sp) &&
+            sane_signal_32_frame(sp)) {
+                sf = (struct signal_frame_32 __user *) (unsigned long) sp;
+                mctx = &sf->mctx;
+        }
+
+        if (!mctx && next_sp - sp >= sizeof(struct rt_signal_frame_32) &&
+            is_rt_sigreturn_32_address(next_ip, sp) &&
+            sane_rt_signal_32_frame(sp)) {
+                rt_sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
+                mctx = &rt_sf->uc.uc_mcontext;
+        }
+
+        if (!mctx)
+                return NULL;
+        return mctx->mc_gregs;
+}
+
+static void perf_callchain_user_32(struct perf_callchain_entry *entry,
+                                   struct pt_regs *regs)
+{
+        unsigned int sp, next_sp;
+        unsigned int next_ip;
+        unsigned int lr;
+        long level = 0;
+        unsigned int __user *fp, *uregs;
+
+        next_ip = regs->nip;
+        lr = regs->link;
+        sp = regs->gpr[1];
+        perf_callchain_store(entry, next_ip);
+
+        while (entry->nr < PERF_MAX_STACK_DEPTH) {
+                fp = (unsigned int __user *) (unsigned long) sp;
+                if (!valid_user_sp(sp, 0) || read_user_stack_32(fp, &next_sp))
+                        return;
+                if (level > 0 && read_user_stack_32(&fp[1], &next_ip))
+                        return;
+
+                uregs = signal_frame_32_regs(sp, next_sp, next_ip);
+                if (!uregs && level <= 1)
+                        uregs = signal_frame_32_regs(sp, next_sp, lr);
+                if (uregs) {
+                        /*
+                         * This looks like an signal frame, so restart
+                         * the stack trace with the values in it.
+                         */
+                        if (read_user_stack_32(&uregs[PT_NIP], &next_ip) ||
+                            read_user_stack_32(&uregs[PT_LNK], &lr) ||
+                            read_user_stack_32(&uregs[PT_R1], &sp))
+                                return;
+                        level = 0;
+                        perf_callchain_store(entry, PERF_CONTEXT_USER);
+                        perf_callchain_store(entry, next_ip);
+                        continue;
+                }
+
+                if (level == 0)
+                        next_ip = lr;
+                perf_callchain_store(entry, next_ip);
+                ++level;
+                sp = next_sp;
+        }
+}
+
+void
+perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
+{
+        if (current_is_64bit())
+                perf_callchain_user_64(entry, regs);
+        else
+                perf_callchain_user_32(entry, regs);
+}