Messages in this thread | | | Date | Mon, 23 Mar 2020 12:14:37 +0000 | From | Mark Rutland <> | Subject | Re: [PATCH 1/3] arm64: clean up trampoline vector loads |
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On Mon, Mar 23, 2020 at 02:08:53PM +0200, Rémi Denis-Courmont wrote: > Le maanantaina 23. maaliskuuta 2020, 14.07.00 EET Mark Rutland a écrit : > > On Thu, Mar 19, 2020 at 11:14:05AM +0200, Rémi Denis-Courmont wrote: > > > From: Rémi Denis-Courmont <remi.denis.courmont@huawei.com> > > > > > > This switches from custom instruction patterns to the regular large > > > memory model sequence with ADRP and LDR. In doing so, the ADD > > > instruction can be eliminated in the SDEI handler, and the code no > > > longer assumes that the trampoline vectors and the vectors address both > > > start on a page boundary. > > > > > > Signed-off-by: Rémi Denis-Courmont <remi.denis.courmont@huawei.com> > > > --- > > > > > > arch/arm64/kernel/entry.S | 9 ++++----- > > > 1 file changed, 4 insertions(+), 5 deletions(-) > > > > > > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > > > index e5d4e30ee242..24f828739696 100644 > > > --- a/arch/arm64/kernel/entry.S > > > +++ b/arch/arm64/kernel/entry.S > > > @@ -805,9 +805,9 @@ alternative_else_nop_endif > > > > > > 2: > > > tramp_map_kernel x30 > > > > > > #ifdef CONFIG_RANDOMIZE_BASE > > > > > > - adr x30, tramp_vectors + PAGE_SIZE > > > + adrp x30, tramp_vectors + PAGE_SIZE > > > > > > alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003 > > > > > > - ldr x30, [x30] > > > + ldr x30, [x30, #:lo12:__entry_tramp_data_start] > > > > I think this is busted for !4K kernels once we reduce the alignment of > > __entry_tramp_data_start. > > > > The ADRP gives us a 64K aligned address (with bits 15:0 clear). The lo12 > > relocation gives us bits 11:0, so we haven't accounted for bits 15:12. > > IMU, ADRP gives a 4K aligned value, regardless of MMU (TCR) settings.
Sorry, I had erroneously assumed tramp_vectors was page aligned. The issue still stands -- we haven't accounted for bits 15:12, as those can differ between tramp_vectors and __entry_tramp_data_start.
Thanks, Mark.
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