From 10573ae547c85b2c61417ff1a106cffbfceada35 Mon Sep 17 00:00:00 2001 From: Russell King Date: Fri, 11 May 2018 11:16:22 +0100 Subject: ARM: spectre-v1: fix syscall entry Prevent speculation at the syscall table decoding by clamping the index used to zero on invalid system call numbers, and using the csdb speculative barrier. Signed-off-by: Russell King Acked-by: Mark Rutland Boot-tested-by: Tony Lindgren Reviewed-by: Tony Lindgren --- arch/arm/kernel/entry-header.S | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'arch/arm/kernel/entry-header.S') diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index 0f07579af472..773424843d6e 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -378,6 +378,31 @@ #endif .endm + .macro invoke_syscall, table, nr, tmp, ret, reload=0 +#ifdef CONFIG_CPU_SPECTRE + mov \tmp, \nr + cmp \tmp, #NR_syscalls @ check upper syscall limit + movcs \tmp, #0 + csdb + badr lr, \ret @ return address + .if \reload + add r1, sp, #S_R0 + S_OFF @ pointer to regs + ldmccia r1, {r0 - r6} @ reload r0-r6 + stmccia sp, {r4, r5} @ update stack arguments + .endif + ldrcc pc, [\table, \tmp, lsl #2] @ call sys_* routine +#else + cmp \nr, #NR_syscalls @ check upper syscall limit + badr lr, \ret @ return address + .if \reload + add r1, sp, #S_R0 + S_OFF @ pointer to regs + ldmccia r1, {r0 - r6} @ reload r0-r6 + stmccia sp, {r4, r5} @ update stack arguments + .endif + ldrcc pc, [\table, \nr, lsl #2] @ call sys_* routine +#endif + .endm + /* * These are the registers used in the syscall handler, and allow us to * have in theory up to 7 arguments to a function - r0 to r6. -- cgit v1.2.3-59-g8ed1b