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e237506238
powerpc 32-bit system call (and function) calling convention for 64-bit
arguments requires the next available odd-pair (two sequential registers
with the first being odd-numbered) from the standard register argument
allocation.
The first argument register is r3, so a 64-bit argument that appears at
an even position in the argument list must skip a register (unless there
were preceding 64-bit arguments, which might throw things off). This
requires non-standard compat definitions to deal with the holes in the
argument register allocation.
With pt_regs syscall wrappers which use a standard mapper to map pt_regs
GPRs to function arguments, 32-bit kernels hit the same basic problem,
the standard definitions don't cope with the unused argument registers.
Fix this by having 32-bit kernels share those syscall definitions with
compat.
Thanks to Jason for spending a lot of time finding and bisecting this
and developing a trivial reproducer. The perfect bug report.
Reported-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Fixes: 7e92e01b72 ("powerpc: Provide syscall wrapper")
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221012035335.866440-1-npiggin@gmail.com
125 lines
3.6 KiB
C
125 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* sys_ppc32.c: 32-bit system calls with complex calling conventions.
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*
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* Copyright (C) 2001 IBM
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* Copyright (C) 1997,1998 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
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* Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
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*
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* 32-bit system calls with 64-bit arguments pass those in register pairs.
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* This must be specially dealt with on 64-bit kernels. The compat_arg_u64_dual
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* in generic compat syscalls is not always usable because the register
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* pairing is constrained depending on preceding arguments.
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*
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* An analogous problem exists on 32-bit kernels with ARCH_HAS_SYSCALL_WRAPPER,
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* the defined system call functions take the pt_regs as an argument, and there
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* is a mapping macro which maps registers to arguments
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* (SC_POWERPC_REGS_TO_ARGS) which also does not deal with these 64-bit
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* arguments.
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*
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* This file contains these system calls.
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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/fs.h>
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#include <linux/mm.h>
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#include <linux/file.h>
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#include <linux/signal.h>
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#include <linux/resource.h>
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#include <linux/times.h>
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#include <linux/smp.h>
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#include <linux/sem.h>
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#include <linux/msg.h>
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#include <linux/shm.h>
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#include <linux/poll.h>
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#include <linux/personality.h>
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#include <linux/stat.h>
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#include <linux/in.h>
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#include <linux/syscalls.h>
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#include <linux/unistd.h>
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#include <linux/sysctl.h>
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#include <linux/binfmts.h>
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#include <linux/security.h>
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#include <linux/compat.h>
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#include <linux/ptrace.h>
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#include <linux/elf.h>
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#include <linux/ipc.h>
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#include <linux/slab.h>
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#include <asm/ptrace.h>
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#include <asm/types.h>
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#include <linux/uaccess.h>
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#include <asm/unistd.h>
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#include <asm/time.h>
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#include <asm/mmu_context.h>
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#include <asm/ppc-pci.h>
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#include <asm/syscalls.h>
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#include <asm/switch_to.h>
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#ifdef CONFIG_PPC32
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#define PPC32_SYSCALL_DEFINE4 SYSCALL_DEFINE4
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#define PPC32_SYSCALL_DEFINE5 SYSCALL_DEFINE5
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#define PPC32_SYSCALL_DEFINE6 SYSCALL_DEFINE6
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#else
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#define PPC32_SYSCALL_DEFINE4 COMPAT_SYSCALL_DEFINE4
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#define PPC32_SYSCALL_DEFINE5 COMPAT_SYSCALL_DEFINE5
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#define PPC32_SYSCALL_DEFINE6 COMPAT_SYSCALL_DEFINE6
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#endif
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PPC32_SYSCALL_DEFINE6(ppc_pread64,
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unsigned int, fd,
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char __user *, ubuf, compat_size_t, count,
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u32, reg6, u32, pos1, u32, pos2)
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{
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return ksys_pread64(fd, ubuf, count, merge_64(pos1, pos2));
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}
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PPC32_SYSCALL_DEFINE6(ppc_pwrite64,
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unsigned int, fd,
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const char __user *, ubuf, compat_size_t, count,
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u32, reg6, u32, pos1, u32, pos2)
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{
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return ksys_pwrite64(fd, ubuf, count, merge_64(pos1, pos2));
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}
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PPC32_SYSCALL_DEFINE5(ppc_readahead,
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int, fd, u32, r4,
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u32, offset1, u32, offset2, u32, count)
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{
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return ksys_readahead(fd, merge_64(offset1, offset2), count);
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}
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PPC32_SYSCALL_DEFINE4(ppc_truncate64,
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const char __user *, path, u32, reg4,
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unsigned long, len1, unsigned long, len2)
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{
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return ksys_truncate(path, merge_64(len1, len2));
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}
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PPC32_SYSCALL_DEFINE4(ppc_ftruncate64,
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unsigned int, fd, u32, reg4,
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unsigned long, len1, unsigned long, len2)
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{
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return ksys_ftruncate(fd, merge_64(len1, len2));
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}
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PPC32_SYSCALL_DEFINE6(ppc32_fadvise64,
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int, fd, u32, unused, u32, offset1, u32, offset2,
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size_t, len, int, advice)
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{
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return ksys_fadvise64_64(fd, merge_64(offset1, offset2), len,
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advice);
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}
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COMPAT_SYSCALL_DEFINE6(ppc_sync_file_range2,
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int, fd, unsigned int, flags,
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unsigned int, offset1, unsigned int, offset2,
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unsigned int, nbytes1, unsigned int, nbytes2)
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{
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loff_t offset = merge_64(offset1, offset2);
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loff_t nbytes = merge_64(nbytes1, nbytes2);
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return ksys_sync_file_range(fd, offset, nbytes, flags);
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}
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