Re: [PATCH v2 0/4] Fixes for vector misaligned load/store handlers

Hi Bo,

On Tue, Jun 9, 2026 at 1:02 AM Bo Gan <[email protected]> wrote:
>
> Re-visit the vector misaligned load/store handlers and fix:
>
> a. Avoid stack overflow by using a small sliding mask[] buffer,
>    thus optimizes stack usage *IMPORTANT* (correctness). There's no-
>    longer a need to have a pre-defined vlen maximum, and worry about
>    whether the stack can hold the mask[] variable.
>
> b. Maintain the value of vstart when redirecting uptrap. (optmization)
>    Avoids doing duplicate work when the instruction gets restarted.
>
> c. Explicitly set VS dirty in (V)SSTATUS. (correctness), VS in
>    VSSTATUS must be set dirty if coming from V=1.
>
> d. Zero out tinst in uptrap if not guest-page fault (correctness).
>
> This is a follow up patch to [1] and should be applied on top.
> [1] https://lore.kernel.org/opensbi/CAEev2e_Vg1mMP4mOKanFX_EGeUzpczRcWW++vBBuN1CfyM0BJw@mail.gmail.com/T/#t
> ---
> v2: Fix the wrong PATCH 4/4 generated in v1.

Testing on Tenstorrent Blackhole with Sifive X280 cores.

After adding some logging like this, I'm still able to break the boot
(like I'd reported on your previous patch). Full logs here
https://gist.github.com/asrinivasanTT/120646cbb7194e7b3505428ebefbdb30

diff --git a/lib/sbi/sbi_trap_v_ldst.c b/lib/sbi/sbi_trap_v_ldst.c
index 0f29dcf9..0f73c339 100644
--- a/lib/sbi/sbi_trap_v_ldst.c
+++ b/lib/sbi/sbi_trap_v_ldst.c
@@ -17,6 +17,7 @@
 #include <sbi/sbi_trap.h>
 #include <sbi/sbi_unpriv.h>
 #include <sbi/sbi_vector.h>
+#include <sbi/sbi_console.h>

 #ifdef OPENSBI_CC_SUPPORT_VECTOR

@@ -163,6 +164,8 @@ static inline void
sbi_misaligned_v_tinst_fixup(struct sbi_trap_info *uptrap)

 int sbi_misaligned_v_ld_emulator(ulong insn, struct sbi_trap_context *tcntx)
 {
+       sbi_printf("%s: insn=0x%lx mepc=0x%lx mtval=0x%lx\n",
+                  __func__, insn, tcntx->regs.mepc, tcntx->trap.tval);
        struct sbi_trap_regs *regs = &tcntx->regs;
        struct sbi_trap_info uptrap;
        ulong vl = csr_read(CSR_VL);
@@ -276,6 +279,8 @@ done:

 int sbi_misaligned_v_st_emulator(ulong insn, struct sbi_trap_context *tcntx)
 {
+       sbi_printf("%s: insn=0x%lx mepc=0x%lx mtval=0x%lx\n",
+               __func__, insn, tcntx->regs.mepc, tcntx->trap.tval);
        struct sbi_trap_regs *regs = &tcntx->regs;
        struct sbi_trap_info uptrap;
        ulong vl = csr_read(CSR_VL);

Is this expected? Are the logging prints causing the overflow?

If I don't have this logging prints added, I'm able to boot fine into
linux. I was able to do this with your last patch, so this patch
doesn't change much in that aspect.

>
> ---
> Bo Gan (4):
>   lib: sbi: cosmetic changes to reduce indentation
>   lib: sbi: Rework and split sbi_misaligned(_v)_tinst_fixup
>   lib: sbi: Add variable-length unprivilege access functions
>   lib: sbi: Rework misaligned vector load/store
>
>  include/sbi/sbi_trap_ldst.h |   3 -
>  include/sbi/sbi_unpriv.h    |  16 +++
>  include/sbi/sbi_vector.h    |   6 ++
>  lib/sbi/sbi_trap_ldst.c     |  66 +++++++-----
>  lib/sbi/sbi_trap_v_ldst.c   | 201 ++++++++++++++++++++++--------------
>  lib/sbi/sbi_unpriv.c        |  88 ++++++++++++++--
>  6 files changed, 270 insertions(+), 110 deletions(-)
>
> --
> 2.34.1
>

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