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![Christophe Leroy](/assets/img/avatar_default.png)
This is copied from arm64. Instead of using runtime generated signal trampoline offsets, get offsets at buildtime. If the said trampoline doesn't exist, build will fail. So no need to check whether the trampoline exists or not in the VDSO. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/f8bfd6812c3e3678b1cdb4d55a52f9eb022b40d3.1601197618.git.christophe.leroy@csgroup.eu
147 lines
3.9 KiB
C
147 lines
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Performance counter callchain support - powerpc architecture code
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*
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* Copyright © 2009 Paul Mackerras, IBM Corporation.
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*/
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/perf_event.h>
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#include <linux/percpu.h>
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#include <linux/uaccess.h>
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#include <linux/mm.h>
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#include <asm/ptrace.h>
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#include <asm/sigcontext.h>
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#include <asm/ucontext.h>
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#include <asm/vdso.h>
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#include <asm/pte-walk.h>
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#include "callchain.h"
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/*
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* On 64-bit we don't want to invoke hash_page on user addresses from
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* interrupt context, so if the access faults, we read the page tables
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* to find which page (if any) is mapped and access it directly. Radix
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* has no need for this so it doesn't use read_user_stack_slow.
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*/
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int read_user_stack_slow(const void __user *ptr, void *buf, int nb)
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{
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unsigned long addr = (unsigned long) ptr;
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unsigned long offset;
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struct page *page;
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void *kaddr;
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if (get_user_page_fast_only(addr, FOLL_WRITE, &page)) {
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kaddr = page_address(page);
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/* align address to page boundary */
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offset = addr & ~PAGE_MASK;
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memcpy(buf, kaddr + offset, nb);
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put_page(page);
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return 0;
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}
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return -EFAULT;
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}
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static int read_user_stack_64(const unsigned long __user *ptr, unsigned long *ret)
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{
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return __read_user_stack(ptr, ret, sizeof(*ret));
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}
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/*
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* 64-bit user processes use the same stack frame for RT and non-RT signals.
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*/
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struct signal_frame_64 {
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char dummy[__SIGNAL_FRAMESIZE];
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struct ucontext uc;
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unsigned long unused[2];
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unsigned int tramp[6];
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struct siginfo *pinfo;
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void *puc;
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struct siginfo info;
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char abigap[288];
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};
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static int is_sigreturn_64_address(unsigned long nip, unsigned long fp)
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{
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if (nip == fp + offsetof(struct signal_frame_64, tramp))
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return 1;
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if (current->mm->context.vdso &&
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nip == VDSO64_SYMBOL(current->mm->context.vdso, sigtramp_rt64))
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return 1;
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return 0;
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}
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/*
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* Do some sanity checking on the signal frame pointed to by sp.
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* We check the pinfo and puc pointers in the frame.
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*/
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static int sane_signal_64_frame(unsigned long sp)
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{
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struct signal_frame_64 __user *sf;
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unsigned long pinfo, puc;
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sf = (struct signal_frame_64 __user *) sp;
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if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) ||
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read_user_stack_64((unsigned long __user *) &sf->puc, &puc))
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return 0;
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return pinfo == (unsigned long) &sf->info &&
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puc == (unsigned long) &sf->uc;
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}
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void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
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struct pt_regs *regs)
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{
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unsigned long sp, next_sp;
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unsigned long next_ip;
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unsigned long lr;
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long level = 0;
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struct signal_frame_64 __user *sigframe;
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unsigned long __user *fp, *uregs;
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next_ip = perf_instruction_pointer(regs);
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lr = regs->link;
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sp = regs->gpr[1];
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perf_callchain_store(entry, next_ip);
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while (entry->nr < entry->max_stack) {
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fp = (unsigned long __user *) sp;
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if (invalid_user_sp(sp) || read_user_stack_64(fp, &next_sp))
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return;
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if (level > 0 && read_user_stack_64(&fp[2], &next_ip))
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return;
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/*
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* Note: the next_sp - sp >= signal frame size check
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* is true when next_sp < sp, which can happen when
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* transitioning from an alternate signal stack to the
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* normal stack.
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*/
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if (next_sp - sp >= sizeof(struct signal_frame_64) &&
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(is_sigreturn_64_address(next_ip, sp) ||
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(level <= 1 && is_sigreturn_64_address(lr, sp))) &&
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sane_signal_64_frame(sp)) {
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/*
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* This looks like an signal frame
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*/
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sigframe = (struct signal_frame_64 __user *) sp;
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uregs = sigframe->uc.uc_mcontext.gp_regs;
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if (read_user_stack_64(&uregs[PT_NIP], &next_ip) ||
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read_user_stack_64(&uregs[PT_LNK], &lr) ||
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read_user_stack_64(&uregs[PT_R1], &sp))
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return;
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level = 0;
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perf_callchain_store_context(entry, PERF_CONTEXT_USER);
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perf_callchain_store(entry, next_ip);
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continue;
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}
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if (level == 0)
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next_ip = lr;
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perf_callchain_store(entry, next_ip);
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++level;
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sp = next_sp;
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}
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}
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