x86/syscall: Mark exit[_group] syscall handlers __noreturn
The direct-call syscall dispatch function doesn't know that the exit()
and exit_group() syscall handlers don't return, so the call sites aren't
optimized accordingly.
Fix that by marking the exit syscall declarations __noreturn.
Fixes the following warnings:
vmlinux.o: warning: objtool: x64_sys_call+0x2804: __x64_sys_exit() is missing a __noreturn annotation
vmlinux.o: warning: objtool: ia32_sys_call+0x29b6: __ia32_sys_exit_group() is missing a __noreturn annotation
Fixes: 1e3ad78334 ("x86/syscall: Don't force use of indirect calls for system calls")
Closes: https://lkml.kernel.org/lkml/6dba9b32-db2c-4e6d-9500-7a08852f17a3@paulmck-laptop
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/5d8882bc077d8eadcc7fd1740b56dfb781f12288.1719381528.git.jpoimboe@kernel.org
This commit is contained in:
Josh Poimboeuf
Borislav Petkov (AMD)
parent
f2661062f1
commit
9142be9e64
@ -14,9 +14,12 @@
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#endif
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#define __SYSCALL(nr, sym) extern long __ia32_##sym(const struct pt_regs *);
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#define __SYSCALL_NORETURN(nr, sym) extern long __noreturn __ia32_##sym(const struct pt_regs *);
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#include <asm/syscalls_32.h>
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#undef __SYSCALL
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#undef __SYSCALL
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#undef __SYSCALL_NORETURN
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#define __SYSCALL_NORETURN __SYSCALL
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/*
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* The sys_call_table[] is no longer used for system calls, but
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@ -28,11 +31,10 @@
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const sys_call_ptr_t sys_call_table[] = {
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#include <asm/syscalls_32.h>
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};
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#undef __SYSCALL
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#undef __SYSCALL
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#endif
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#define __SYSCALL(nr, sym) case nr: return __ia32_##sym(regs);
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long ia32_sys_call(const struct pt_regs *regs, unsigned int nr)
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{
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switch (nr) {
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@ -8,8 +8,12 @@
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#include <asm/syscall.h>
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#define __SYSCALL(nr, sym) extern long __x64_##sym(const struct pt_regs *);
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#define __SYSCALL_NORETURN(nr, sym) extern long __noreturn __x64_##sym(const struct pt_regs *);
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#include <asm/syscalls_64.h>
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#undef __SYSCALL
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#undef __SYSCALL
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#undef __SYSCALL_NORETURN
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#define __SYSCALL_NORETURN __SYSCALL
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/*
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* The sys_call_table[] is no longer used for system calls, but
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@ -20,10 +24,9 @@
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const sys_call_ptr_t sys_call_table[] = {
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#include <asm/syscalls_64.h>
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};
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#undef __SYSCALL
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#undef __SYSCALL
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#define __SYSCALL(nr, sym) case nr: return __x64_##sym(regs);
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long x64_sys_call(const struct pt_regs *regs, unsigned int nr)
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{
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switch (nr) {
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@ -8,11 +8,14 @@
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#include <asm/syscall.h>
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#define __SYSCALL(nr, sym) extern long __x64_##sym(const struct pt_regs *);
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#define __SYSCALL_NORETURN(nr, sym) extern long __noreturn __x64_##sym(const struct pt_regs *);
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#include <asm/syscalls_x32.h>
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#undef __SYSCALL
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#undef __SYSCALL
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#undef __SYSCALL_NORETURN
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#define __SYSCALL_NORETURN __SYSCALL
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#define __SYSCALL(nr, sym) case nr: return __x64_##sym(regs);
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long x32_sys_call(const struct pt_regs *regs, unsigned int nr)
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{
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switch (nr) {
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@ -2,7 +2,7 @@
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# 32-bit system call numbers and entry vectors
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#
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# The format is:
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# <number> <abi> <name> <entry point> <compat entry point>
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# <number> <abi> <name> <entry point> [<compat entry point> [noreturn]]
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#
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# The __ia32_sys and __ia32_compat_sys stubs are created on-the-fly for
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# sys_*() system calls and compat_sys_*() compat system calls if
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@ -12,7 +12,7 @@
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# The abi is always "i386" for this file.
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#
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0 i386 restart_syscall sys_restart_syscall
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1 i386 exit sys_exit
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1 i386 exit sys_exit - noreturn
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2 i386 fork sys_fork
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3 i386 read sys_read
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4 i386 write sys_write
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@ -263,7 +263,7 @@
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249 i386 io_cancel sys_io_cancel
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250 i386 fadvise64 sys_ia32_fadvise64
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# 251 is available for reuse (was briefly sys_set_zone_reclaim)
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252 i386 exit_group sys_exit_group
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252 i386 exit_group sys_exit_group - noreturn
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253 i386 lookup_dcookie
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254 i386 epoll_create sys_epoll_create
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255 i386 epoll_ctl sys_epoll_ctl
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@ -2,7 +2,7 @@
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# 64-bit system call numbers and entry vectors
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#
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# The format is:
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# <number> <abi> <name> <entry point>
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# <number> <abi> <name> <entry point> [<compat entry point> [noreturn]]
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#
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# The __x64_sys_*() stubs are created on-the-fly for sys_*() system calls
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#
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@ -68,7 +68,7 @@
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57 common fork sys_fork
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58 common vfork sys_vfork
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59 64 execve sys_execve
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60 common exit sys_exit
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60 common exit sys_exit - noreturn
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61 common wait4 sys_wait4
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62 common kill sys_kill
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63 common uname sys_newuname
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@ -239,7 +239,7 @@
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228 common clock_gettime sys_clock_gettime
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229 common clock_getres sys_clock_getres
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230 common clock_nanosleep sys_clock_nanosleep
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231 common exit_group sys_exit_group
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231 common exit_group sys_exit_group - noreturn
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232 common epoll_wait sys_epoll_wait
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233 common epoll_ctl sys_epoll_ctl
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234 common tgkill sys_tgkill
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@ -9,6 +9,10 @@
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#include <linux/cache.h>
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#include <asm/syscall.h>
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extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long,
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unsigned long, unsigned long,
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unsigned long, unsigned long);
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/*
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* Below you can see, in terms of #define's, the differences between the x86-64
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* and the UML syscall table.
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@ -22,15 +26,13 @@
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#define sys_vm86 sys_ni_syscall
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#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native)
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#define __SYSCALL_NORETURN __SYSCALL
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#define __SYSCALL(nr, sym) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long);
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#include <asm/syscalls_32.h>
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#undef __SYSCALL
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#undef __SYSCALL
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#define __SYSCALL(nr, sym) sym,
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extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long);
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const sys_call_ptr_t sys_call_table[] ____cacheline_aligned = {
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#include <asm/syscalls_32.h>
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};
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@ -9,6 +9,10 @@
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#include <linux/cache.h>
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#include <asm/syscall.h>
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extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long,
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unsigned long, unsigned long,
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unsigned long, unsigned long);
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/*
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* Below you can see, in terms of #define's, the differences between the x86-64
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* and the UML syscall table.
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@ -18,14 +22,13 @@
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#define sys_iopl sys_ni_syscall
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#define sys_ioperm sys_ni_syscall
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#define __SYSCALL_NORETURN __SYSCALL
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#define __SYSCALL(nr, sym) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long);
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#include <asm/syscalls_64.h>
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#undef __SYSCALL
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#undef __SYSCALL
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#define __SYSCALL(nr, sym) sym,
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extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long);
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const sys_call_ptr_t sys_call_table[] ____cacheline_aligned = {
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#include <asm/syscalls_64.h>
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};
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@ -54,7 +54,7 @@ nxt=0
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grep -E "^[0-9]+[[:space:]]+$abis" "$infile" | {
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while read nr abi name native compat ; do
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while read nr abi name native compat noreturn; do
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if [ $nxt -gt $nr ]; then
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echo "error: $infile: syscall table is not sorted or duplicates the same syscall number" >&2
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@ -66,7 +66,21 @@ grep -E "^[0-9]+[[:space:]]+$abis" "$infile" | {
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nxt=$((nxt + 1))
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done
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if [ -n "$compat" ]; then
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if [ "$compat" = "-" ]; then
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unset compat
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fi
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if [ -n "$noreturn" ]; then
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if [ "$noreturn" != "noreturn" ]; then
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echo "error: $infile: invalid string \"$noreturn\" in 'noreturn' column"
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exit 1
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fi
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if [ -n "$compat" ]; then
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echo "__SYSCALL_COMPAT_NORETURN($nr, $native, $compat)"
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else
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echo "__SYSCALL_NORETURN($nr, $native)"
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fi
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elif [ -n "$compat" ]; then
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echo "__SYSCALL_WITH_COMPAT($nr, $native, $compat)"
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elif [ -n "$native" ]; then
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echo "__SYSCALL($nr, $native)"
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@ -7,12 +7,16 @@
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* Yes, this is unfortunate. A better solution is in the works.
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*/
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NORETURN(__fortify_panic)
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NORETURN(__ia32_sys_exit)
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NORETURN(__ia32_sys_exit_group)
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NORETURN(__kunit_abort)
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NORETURN(__module_put_and_kthread_exit)
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NORETURN(__reiserfs_panic)
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NORETURN(__stack_chk_fail)
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NORETURN(__tdx_hypercall_failed)
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NORETURN(__ubsan_handle_builtin_unreachable)
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NORETURN(__x64_sys_exit)
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NORETURN(__x64_sys_exit_group)
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NORETURN(arch_cpu_idle_dead)
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NORETURN(bch2_trans_in_restart_error)
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NORETURN(bch2_trans_restart_error)
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