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Hi,
I think gcore or
other client,no need
to understand what
is zram and just call
readmem to get the data.so i encapsulate try_zram_decompress to readmem,gcore just calling readmem can get right data.It will have
better encapsulation,If one day the kernel provides other ram swap,Do we need to add changes in gcore synchronously?
If it's just for historical reasons and the problem has been solved,keep this code is unnecessary,it's just my consideration.
The first patch I made was calling try_zram_decompress in gcore.You can also think about this patch.
Thanks.
From: d.hatayama@xxxxxxxxxxx <d.hatayama@xxxxxxxxxxx>
Sent: Wednesday, April 15, 2020 20:25
To: 赵乾利; Dave Anderson
Cc: Discussion list for crash utility usage, maintenance and development
Subject: Re: 答复: [External Mail]Re: zram decompress support for gcore/crash-utility
Hi,
Hi,Hatayama
Since zram page not a existing page,so we can't use vtop find exactly physical address,so gcore have to make a little change for this.gcore patch i've already sent in previous mail
Please don't remove uvtop_quiet(), which is necessary. The reason is to avoid some bug in crash utility in the past as written in the comment in uvtop_quiet().
Looking at the following stanza, the necessary change is to add a call of try_zram_decompress() when uvtop_quiet() returns false but paddr is non-zero.
defs.h belongs to crash utility. Please don't post change of defs.h to crash gcore command.
I've answered your question in the previous email about exactly kernel commit in aarch64 stack,please refer to below change
The latest two changes are attached,please review.
Thanks. I'll review this later.
commit 34be98f4944f99076f049a6806fc5f5207a755d3
Author: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Date: Thu Jul 20 17:15:45 2017 +0100
arm64: kernel: remove {THREAD,IRQ_STACK}_START_SP
For historical reasons, we leave the top 16 bytes of our task and IRQ
stacks unused, a practice used to ensure that the SP can always be
masked to find the base of the current stack (historically, where
thread_info could be found).
However, this is not necessary, as:
* When an exception is taken from a task stack, we decrement the SP by
S_FRAME_SIZE and stash the exception registers before we compare the
SP against the task stack. In such cases, the SP must be at least
S_FRAME_SIZE below the limit, and can be safely masked to determine
whether the task stack is in use.
* When transitioning to an IRQ stack, we'll place a dummy frame onto the
IRQ stack before enabling asynchronous exceptions, or executing code
we expect to trigger faults. Thus, if an exception is taken from the
IRQ stack, the SP must be at least 16 bytes below the limit.
* We no longer mask the SP to find the thread_info, which is now found
via sp_el0. Note that historically, the offset was critical to ensure
that cpu_switch_to() found the correct stack for new threads that
hadn't yet executed ret_from_fork().
Given that, this initial offset serves no purpose, and can be removed.
This brings us in-line with other architectures (e.g. x86) which do not
rely on this masking.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
[Mark: rebase, kill THREAD_START_SP, commit msg additions]
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Reviewed-by: Will Deacon <will.deacon@xxxxxxx>
Tested-by: Laura Abbott <labbott@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: James Morse <james.morse@xxxxxxx>
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