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| author |  Linus Torvalds <torvalds@linux-foundation.org>
| 2024-04-03 16:36:44 -0700 |
|---|---|---|
| committer |  Thomas Gleixner <tglx@linutronix.de>
| 2024-04-08 19:27:05 +0200 |
| commit | 1e3ad78334a69b36e107232e337f9d693dcc9df2 (patch) | |
| tree | 11162955093106a59ca3825365580797e0aff750 /arch/x86/entry/common.c | |
| parent | x86/bugs: Change commas to semicolons in 'spectre_v2' sysfs file (diff) | |
| download | linux-1e3ad78334a69b36e107232e337f9d693dcc9df2.tar.gz linux-1e3ad78334a69b36e107232e337f9d693dcc9df2.tar.bz2 linux-1e3ad78334a69b36e107232e337f9d693dcc9df2.zip | |
x86/syscall: Don't force use of indirect calls for system calls
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>
Diffstat (limited to 'arch/x86/entry/common.c')
| -rw-r--r-- | arch/x86/entry/common.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 6356060caaf3..cea0e2a23b42 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -49,7 +49,7 @@ static __always_inline bool do_syscall_x64(struct pt_regs *regs, int nr) if (likely(unr < NR_syscalls)) { unr = array_index_nospec(unr, NR_syscalls); - regs->ax = sys_call_table[unr](regs); + regs->ax = x64_sys_call(regs, unr); return true; } return false; @@ -66,7 +66,7 @@ static __always_inline bool do_syscall_x32(struct pt_regs *regs, int nr) if (IS_ENABLED(CONFIG_X86_X32_ABI) && likely(xnr < X32_NR_syscalls)) { xnr = array_index_nospec(xnr, X32_NR_syscalls); - regs->ax = x32_sys_call_table[xnr](regs); + regs->ax = x32_sys_call(regs, xnr); return true; } return false; @@ -162,7 +162,7 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs, int nr) if (likely(unr < IA32_NR_syscalls)) { unr = array_index_nospec(unr, IA32_NR_syscalls); - regs->ax = ia32_sys_call_table[unr](regs); + regs->ax = ia32_sys_call(regs, unr); } else if (nr != -1) { regs->ax = __ia32_sys_ni_syscall(regs); } |