diff options
| author | Mark Rutland <mark.rutland@arm.com> | 2018-07-11 15:56:48 +0200 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2018-07-12 15:49:47 +0200 |
| commit | baaa7237fecc5ada99e518f38541126977ca7ff4 (patch) | |
| tree | 3816c163ef9d02a4bd72a1ed83bb38932a7c36b1 /arch/arm64 | |
| parent | arm64: don't reload GPRs after apply_ssbd (diff) | |
| download | linux-baaa7237fecc5ada99e518f38541126977ca7ff4.tar.xz linux-baaa7237fecc5ada99e518f38541126977ca7ff4.zip | |
arm64: zero GPRs upon entry from EL0
We can zero GPRs x0 - x29 upon entry from EL0 to make it harder for
userspace to control values consumed by speculative gadgets.
We don't blat x30, since this is stashed much later, and we'll blat it
before invoking C code.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 22b240da949b..d1440f84668b 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -53,6 +53,12 @@ #endif .endm + .macro clear_gp_regs + .irp n,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29 + mov x\n, xzr + .endr + .endm + /* * Bad Abort numbers *----------------- @@ -169,6 +175,7 @@ alternative_cb_end stp x28, x29, [sp, #16 * 14] .if \el == 0 + clear_gp_regs mrs x21, sp_el0 ldr_this_cpu tsk, __entry_task, x20 // Ensure MDSCR_EL1.SS is clear, ldr x19, [tsk, #TSK_TI_FLAGS] // since we can unmask debug @@ -176,7 +183,6 @@ alternative_cb_end apply_ssbd 1, x22, x23 - mov x29, xzr // fp pointed to user-space .else add x21, sp, #S_FRAME_SIZE get_thread_info tsk |