--- /dev/null
+/*
+ * 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_MIN_SIZE)
+ 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, perf_instruction_pointer(regs));
+
+ 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 *buf, int nb)
+{
+ int ret = -EFAULT;
+ pgd_t *pgdir;
+ pte_t *ptep, pte;
+ unsigned shift;
+ unsigned long addr = (unsigned long) ptr;
+ unsigned long offset;
+ unsigned long pfn, flags;
+ void *kaddr;
+
+ pgdir = current->mm->pgd;
+ if (!pgdir)
+ return -EFAULT;
+
+ local_irq_save(flags);
+ ptep = find_linux_pte_or_hugepte(pgdir, addr, &shift);
+ if (!ptep)
+ goto err_out;
+ if (!shift)
+ shift = PAGE_SHIFT;
+
+ /* align address to page boundary */
+ offset = addr & ((1UL << shift) - 1);
+
+ pte = READ_ONCE(*ptep);
+ if (!pte_present(pte) || !(pte_val(pte) & _PAGE_USER))
+ goto err_out;
+ pfn = pte_pfn(pte);
+ if (!page_is_ram(pfn))
+ goto err_out;
+
+ /* no highmem to worry about here */
+ kaddr = pfn_to_kaddr(pfn);
+ memcpy(buf, kaddr + offset, nb);
+ ret = 0;
+err_out:
+ local_irq_restore(flags);
+ return ret;
+}
+
+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 = perf_instruction_pointer(regs);
+ lr = regs->link;
+ sp = regs->gpr[1];
+ perf_callchain_store(entry, next_ip);
+
+ while (entry->nr < PERF_MAX_STACK_DEPTH) {
+ 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, ®s))
+ 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, ®s))
+ 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 = perf_instruction_pointer(regs);
+ 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);
+}
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