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-rw-r--r--arch/powerpc/perf/callchain_64.c174
1 files changed, 174 insertions, 0 deletions
diff --git a/arch/powerpc/perf/callchain_64.c b/arch/powerpc/perf/callchain_64.c
new file mode 100644
index 000000000000..df1ffd8b20f2
--- /dev/null
+++ b/arch/powerpc/perf/callchain_64.c
@@ -0,0 +1,174 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Performance counter callchain support - powerpc architecture code
+ *
+ * Copyright © 2009 Paul Mackerras, IBM Corporation.
+ */
+#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>
+#include <asm/pte-walk.h>
+
+#include "callchain.h"
+
+/*
+ * 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.
+ */
+int read_user_stack_slow(void __user *ptr, void *buf, int nb)
+{
+ int ret = -EFAULT;
+ pgd_t *pgdir;
+ pte_t *ptep, pte;
+ unsigned int 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_current_mm_pte(pgdir, addr, NULL, &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_user(pte))
+ 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;
+
+ if (!probe_user_read(ret, ptr, sizeof(*ret)))
+ return 0;
+
+ return read_user_stack_slow(ptr, ret, 8);
+}
+
+/*
+ * 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;
+}
+
+void perf_callchain_user_64(struct perf_callchain_entry_ctx *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 < entry->max_stack) {
+ fp = (unsigned long __user *) sp;
+ if (invalid_user_sp(sp) || 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_context(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;
+ }
+}