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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-28 11:18:45 +07:00
6365b842aa
For unfortunate historical reasons, the x32 syscalls and the x86_64 syscalls are not all numbered the same. As an example, ioctl() is nr 16 on x86_64 but 514 on x32. This has potentially nasty consequences, since it means that there are two valid RAX values to do ioctl(2) and two invalid RAX values. The valid values are 16 (i.e. ioctl(2) using the x86_64 ABI) and (514 | 0x40000000) (i.e. ioctl(2) using the x32 ABI). The invalid values are 514 and (16 | 0x40000000). 514 will enter the "COMPAT_SYSCALL_DEFINE3(ioctl, ...)" entry point with in_compat_syscall() and in_x32_syscall() returning false, whereas (16 | 0x40000000) will enter the native entry point with in_compat_syscall() and in_x32_syscall() returning true. Both are bogus, and both will exercise code paths in the kernel and in any running seccomp filters that really ought to be unreachable. Splitting out the x32 syscalls into their own tables, allows both bogus invocations to return -ENOSYS. I've checked glibc, musl, and Bionic, and all of them appear to call syscalls with their correct numbers, so this change should have no effect on them. There is an added benefit going forward: new syscalls that need special handling on x32 can share the same number on x32 and x86_64. This means that the special syscall range 512-547 can be treated as a legacy wart instead of something that may need to be extended in the future. Also add a selftest to verify the new behavior. Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/208024256b764312598f014ebfb0a42472c19354.1562185330.git.luto@kernel.org
85 lines
2.0 KiB
Bash
85 lines
2.0 KiB
Bash
#!/bin/bash
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# SPDX-License-Identifier: GPL-2.0
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in="$1"
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out="$2"
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syscall_macro() {
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local abi="$1"
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local nr="$2"
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local entry="$3"
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# Entry can be either just a function name or "function/qualifier"
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real_entry="${entry%%/*}"
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if [ "$entry" = "$real_entry" ]; then
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qualifier=
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else
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qualifier=${entry#*/}
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fi
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echo "__SYSCALL_${abi}($nr, $real_entry, $qualifier)"
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}
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emit() {
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local abi="$1"
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local nr="$2"
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local entry="$3"
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local compat="$4"
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local umlentry=""
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if [ "$abi" != "I386" -a -n "$compat" ]; then
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echo "a compat entry ($abi: $compat) for a 64-bit syscall makes no sense" >&2
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exit 1
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fi
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# For CONFIG_UML, we need to strip the __x64_sys prefix
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if [ "$abi" = "64" -a "${entry}" != "${entry#__x64_sys}" ]; then
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umlentry="sys${entry#__x64_sys}"
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fi
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if [ -z "$compat" ]; then
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if [ -n "$entry" -a -z "$umlentry" ]; then
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syscall_macro "$abi" "$nr" "$entry"
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elif [ -n "$umlentry" ]; then # implies -n "$entry"
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echo "#ifdef CONFIG_X86"
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syscall_macro "$abi" "$nr" "$entry"
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echo "#else /* CONFIG_UML */"
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syscall_macro "$abi" "$nr" "$umlentry"
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echo "#endif"
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fi
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else
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echo "#ifdef CONFIG_X86_32"
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if [ -n "$entry" ]; then
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syscall_macro "$abi" "$nr" "$entry"
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fi
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echo "#else"
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syscall_macro "$abi" "$nr" "$compat"
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echo "#endif"
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fi
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}
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grep '^[0-9]' "$in" | sort -n | (
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while read nr abi name entry compat; do
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abi=`echo "$abi" | tr '[a-z]' '[A-Z]'`
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if [ "$abi" = "COMMON" -o "$abi" = "64" ]; then
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emit 64 "$nr" "$entry" "$compat"
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if [ "$abi" = "COMMON" ]; then
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# COMMON means that this syscall exists in the same form for
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# 64-bit and X32.
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echo "#ifdef CONFIG_X86_X32_ABI"
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emit X32 "$nr" "$entry" "$compat"
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echo "#endif"
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fi
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elif [ "$abi" = "X32" ]; then
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echo "#ifdef CONFIG_X86_X32_ABI"
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emit X32 "$nr" "$entry" "$compat"
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echo "#endif"
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elif [ "$abi" = "I386" ]; then
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emit "$abi" "$nr" "$entry" "$compat"
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else
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echo "Unknown abi $abi" >&2
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exit 1
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fi
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done
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) > "$out"
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