From: Oleksii <oleksii.kurochko@gmail.com>
To: Andrew Cooper <Andrew.Cooper3@citrix.com>,
"xen-devel@lists.xenproject.org"
<xen-devel@lists.xenproject.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
Gianluca Guida <gianluca@rivosinc.com>,
Bob Eshleman <bobbyeshleman@gmail.com>,
Alistair Francis <alistair.francis@wdc.com>,
Connor Davis <connojdavis@gmail.com>
Subject: Re: [PATCH v1 07/14] xen/riscv: introduce exception handlers implementation
Date: Wed, 25 Jan 2023 16:44:36 +0200 [thread overview]
Message-ID: <ca20e076ae8af5ae0924a19e73352ac9d7e7a202.camel@gmail.com> (raw)
In-Reply-To: <ac6f02e8-c493-7914-f3c4-32b4ebe1bc26@citrix.com>
On Mon, 2023-01-23 at 11:50 +0000, Andrew Cooper wrote:
>
>
> > + /* Save context to stack */
> > + REG_S sp, (RISCV_CPU_USER_REGS_OFFSET(sp) -
> > RISCV_CPU_USER_REGS_SIZE) (sp)
> > + addi sp, sp, -RISCV_CPU_USER_REGS_SIZE
> > + REG_S t0, RISCV_CPU_USER_REGS_OFFSET(t0)(sp)
>
> Exceptions on RISC-V don't adjust the stack pointer. This logic
> depends
> on interrupting Xen code, and Xen not having suffered a stack
> overflow
> (and actually, that the space on the stack for all registers also
> doesn't overflow).
>
Probably I missed something but an idea of the code above was to
reserve memory on a stack to save the registers which can be changed
in __handler_expception() as the line of code where exception occurs
will expect that registers value weren't changed.
Otherwise if we won't reserve memory on stack it will be corrupted by
REG_S which basically is SD instruction.
next prev parent reply other threads:[~2023-01-25 14:44 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-20 14:59 [PATCH v1 00/14] RISCV basic exception handling implementation Oleksii Kurochko
2023-01-20 14:59 ` [PATCH v1 01/14] xen/riscv: add _zicsr to CFLAGS Oleksii Kurochko
2023-01-20 15:29 ` Andrew Cooper
2023-01-23 10:43 ` Oleksii
2023-01-31 11:49 ` Alistair Francis
2023-01-31 12:30 ` Oleksii
2023-01-20 14:59 ` [PATCH v1 02/14] xen/riscv: add <asm/asm.h> header Oleksii Kurochko
2023-01-20 15:31 ` Andrew Cooper
2023-01-23 11:00 ` Jan Beulich
2023-01-23 11:10 ` Andrew Cooper
2023-01-22 22:58 ` Alistair Francis
2023-01-20 14:59 ` [PATCH v1 03/14] xen/riscv: add <asm/riscv_encoding.h header Oleksii Kurochko
2023-01-22 23:24 ` Alistair Francis
2023-01-23 13:52 ` Jan Beulich
2023-01-23 14:04 ` Oleksii
2023-01-23 14:06 ` Jan Beulich
2023-01-20 14:59 ` [PATCH v1 04/14] xen/riscv: add <asm/csr.h> header Oleksii Kurochko
2023-01-22 23:25 ` Alistair Francis
2023-01-23 13:57 ` Jan Beulich
2023-01-23 14:23 ` Oleksii
2023-01-23 14:31 ` Jan Beulich
2023-01-20 14:59 ` [PATCH v1 05/14] xen/riscv: add early_printk_hnum() function Oleksii Kurochko
2023-01-20 15:39 ` Andrew Cooper
2023-01-23 12:05 ` Oleksii
2023-01-23 11:10 ` Jan Beulich
2023-01-20 14:59 ` [PATCH v1 06/14] xen/riscv: introduce exception context Oleksii Kurochko
2023-01-20 15:54 ` Andrew Cooper
2023-01-23 12:03 ` Oleksii
2023-01-23 12:25 ` Andrew Cooper
2023-01-23 11:13 ` Jan Beulich
2023-01-20 14:59 ` [PATCH v1 07/14] xen/riscv: introduce exception handlers implementation Oleksii Kurochko
2023-01-22 23:29 ` Alistair Francis
2023-01-23 11:17 ` Jan Beulich
2023-01-23 15:04 ` Oleksii
2023-01-23 11:50 ` Andrew Cooper
2023-01-23 12:41 ` Jan Beulich
2023-01-23 15:17 ` Oleksii
2023-01-23 20:09 ` Andrew Cooper
2023-01-25 14:44 ` Oleksii [this message]
2023-01-20 14:59 ` [PATCH v1 08/14] xen/riscv: introduce decode_cause() stuff Oleksii Kurochko
2023-01-22 23:38 ` Alistair Francis
2023-01-23 12:09 ` Andrew Cooper
2023-01-20 14:59 ` [PATCH v1 09/14] xen/riscv: introduce do_unexpected_trap() Oleksii Kurochko
2023-01-22 23:39 ` Alistair Francis
2023-01-25 17:01 ` Oleksii
2023-01-25 17:11 ` Julien Grall
2023-01-25 17:15 ` Andrew Cooper
2023-01-26 8:40 ` Oleksii
2023-01-20 14:59 ` [PATCH v1 10/14] xen/riscv: mask all interrupts Oleksii Kurochko
2023-01-22 23:40 ` Alistair Francis
2023-01-20 14:59 ` [PATCH v1 11/14] xen/riscv: introduce setup_trap_handler() Oleksii Kurochko
2023-01-22 23:41 ` Alistair Francis
2023-01-23 23:21 ` Andrew Cooper
2023-01-20 14:59 ` [PATCH v1 12/14] xen/riscv: introduce an implementation of macros from <asm/bug.h> Oleksii Kurochko
2023-01-23 11:37 ` Jan Beulich
2023-01-20 14:59 ` [PATCH v1 13/14] xen/riscv: test basic handling stuff Oleksii Kurochko
2023-01-20 14:59 ` [PATCH v1 14/14] automation: add smoke test to verify macros from bug.h Oleksii Kurochko
2023-01-24 23:53 ` Stefano Stabellini
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