| Message ID | 20211126180411.187597-1-mick@ics.forth.gr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/3] riscv: Don't use va_pa_offset on kdump | expand |
Hello Palmer, Any updates on those 3 patches ? Regards, Nick Στις 2021-11-26 20:04, Nick Kossifidis έγραψε: > On kdump instead of using an intermediate step to relocate the kernel, > that lives in a "control buffer" outside the current kernel's mapping, > we jump to the crash kernel directly by calling > riscv_kexec_norelocate(). > The current implementation uses va_pa_offset while switching to > physical > addressing, however since we moved the kernel outside the linear > mapping > this won't work anymore since riscv_kexec_norelocate() is part of the > kernel mapping and we should use kernel_map.va_kernel_pa_offset, and > also > take XIP kernel into account. > > We don't really need to use va_pa_offset on riscv_kexec_norelocate, we > can just set STVEC to the physical address of the new kernel instead > and > let the hart jump to the new kernel on the next instruction after > setting > SATP to zero. This fixes kdump and is also simpler/cleaner. > > I tested this on the latest qemu and HiFive Unmatched and works as > expected. > > v2: I removed the direct jump after setting satp as suggested. > > Fixes: 2bfc6cd81bd1 ("riscv: Move kernel mapping outside of linear > mapping") > > Signed-off-by: Nick Kossifidis <mick@ics.forth.gr> > Reviewed-by: Alexandre Ghiti <alex@ghiti.fr> > Cc: <stable@vger.kernel.org> # 5.13 > Cc: <stable@vger.kernel.org> # 5.14
On Fri, 07 Jan 2022 10:03:59 PST (-0800), mick@ics.forth.gr wrote: > Hello Palmer, > > Any updates on those 3 patches ? Sorry, I hadn't realized these were fixes so they got stuck in the queue0. I do now remember you saying you had some fixes at the RISC-V conference, but I guess that got lost as well. Including something like "fix" or "-fixes" in a subject line always helps, but if I miss stuff IRC's always a good bet as that'll at least make sure I see it when I'm in front of the computer -- there's a lot of people who want things at these conferences. It's too late for fixes, but it looks like things have been broken for a while so these will have to all get backported to stable regardless. This is on for-next. Thanks! > > Regards, > Nick > > Στις 2021-11-26 20:04, Nick Kossifidis έγραψε: >> On kdump instead of using an intermediate step to relocate the kernel, >> that lives in a "control buffer" outside the current kernel's mapping, >> we jump to the crash kernel directly by calling >> riscv_kexec_norelocate(). >> The current implementation uses va_pa_offset while switching to >> physical >> addressing, however since we moved the kernel outside the linear >> mapping >> this won't work anymore since riscv_kexec_norelocate() is part of the >> kernel mapping and we should use kernel_map.va_kernel_pa_offset, and >> also >> take XIP kernel into account. >> >> We don't really need to use va_pa_offset on riscv_kexec_norelocate, we >> can just set STVEC to the physical address of the new kernel instead >> and >> let the hart jump to the new kernel on the next instruction after >> setting >> SATP to zero. This fixes kdump and is also simpler/cleaner. >> >> I tested this on the latest qemu and HiFive Unmatched and works as >> expected. >> >> v2: I removed the direct jump after setting satp as suggested. >> >> Fixes: 2bfc6cd81bd1 ("riscv: Move kernel mapping outside of linear >> mapping") >> >> Signed-off-by: Nick Kossifidis <mick@ics.forth.gr> >> Reviewed-by: Alexandre Ghiti <alex@ghiti.fr> >> Cc: <stable@vger.kernel.org> # 5.13 >> Cc: <stable@vger.kernel.org> # 5.14
diff --git a/arch/riscv/kernel/kexec_relocate.S b/arch/riscv/kernel/kexec_relocate.S index a80b52a74..059c5e216 100644 --- a/arch/riscv/kernel/kexec_relocate.S +++ b/arch/riscv/kernel/kexec_relocate.S @@ -159,25 +159,15 @@ SYM_CODE_START(riscv_kexec_norelocate) * s0: (const) Phys address to jump to * s1: (const) Phys address of the FDT image * s2: (const) The hartid of the current hart - * s3: (const) kernel_map.va_pa_offset, used when switching MMU off */ mv s0, a1 mv s1, a2 mv s2, a3 - mv s3, a4 /* Disable / cleanup interrupts */ csrw CSR_SIE, zero csrw CSR_SIP, zero - /* Switch to physical addressing */ - la s4, 1f - sub s4, s4, s3 - csrw CSR_STVEC, s4 - csrw CSR_SATP, zero - -.align 2 -1: /* Pass the arguments to the next kernel / Cleanup*/ mv a0, s2 mv a1, s1 @@ -214,7 +204,15 @@ SYM_CODE_START(riscv_kexec_norelocate) csrw CSR_SCAUSE, zero csrw CSR_SSCRATCH, zero - jalr zero, a2, 0 + /* + * Switch to physical addressing + * This will also trigger a jump to CSR_STVEC + * which in this case is the address of the new + * kernel. + */ + csrw CSR_STVEC, a2 + csrw CSR_SATP, zero + SYM_CODE_END(riscv_kexec_norelocate) .section ".rodata"
On kdump instead of using an intermediate step to relocate the kernel, that lives in a "control buffer" outside the current kernel's mapping, we jump to the crash kernel directly by calling riscv_kexec_norelocate(). The current implementation uses va_pa_offset while switching to physical addressing, however since we moved the kernel outside the linear mapping this won't work anymore since riscv_kexec_norelocate() is part of the kernel mapping and we should use kernel_map.va_kernel_pa_offset, and also take XIP kernel into account. We don't really need to use va_pa_offset on riscv_kexec_norelocate, we can just set STVEC to the physical address of the new kernel instead and let the hart jump to the new kernel on the next instruction after setting SATP to zero. This fixes kdump and is also simpler/cleaner. I tested this on the latest qemu and HiFive Unmatched and works as expected. v2: I removed the direct jump after setting satp as suggested. Fixes: 2bfc6cd81bd1 ("riscv: Move kernel mapping outside of linear mapping") Signed-off-by: Nick Kossifidis <mick@ics.forth.gr> Reviewed-by: Alexandre Ghiti <alex@ghiti.fr> Cc: <stable@vger.kernel.org> # 5.13 Cc: <stable@vger.kernel.org> # 5.14 --- arch/riscv/kernel/kexec_relocate.S | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-)