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https://gitee.com/bianbu-linux/linux-6.6
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eb0f175b34
commit 1e3ad78334a69b36e107232e337f9d693dcc9df2 upstream. Make <asm/syscall.h> build a switch statement instead, and the compiler can either decide to generate an indirect jump, or - more likely these days due to mitigations - just a series of conditional branches. Yes, the conditional branches also have branch prediction, but the branch prediction is much more controlled, in that it just causes speculatively running the wrong system call (harmless), rather than speculatively running possibly wrong random less controlled code gadgets. This doesn't mitigate other indirect calls, but the system call indirection is the first and most easily triggered case. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
33 lines
833 B
C
33 lines
833 B
C
// SPDX-License-Identifier: GPL-2.0
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/* System call table for x86-64. */
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#include <linux/linkage.h>
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#include <linux/sys.h>
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#include <linux/cache.h>
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#include <linux/syscalls.h>
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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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#include <asm/syscalls_64.h>
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#undef __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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* kernel/trace/trace_syscalls.c still wants to know the system
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* call address.
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*/
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#define __SYSCALL(nr, sym) __x64_##sym,
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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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#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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#include <asm/syscalls_64.h>
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default: return __x64_sys_ni_syscall(regs);
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}
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};
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