发件人: Jakob Gruber
发送时间: 2020年8月26日 13:27
收件人: v8-dev@googlegroups.com
主题: Re: [v8-dev]
Not sure I understand what you said. The JSEntryTrampoline call itself, here,
is fine; but the call target, generated here, should have been fixed up by
mksnapshot to point at the off-heap instruction stream for the
JSEntryTrampoline. That happens here on x64, other platforms have different
mechanisms. Perhaps one of those parts is missing in your port? See also the
design for embedded builtins (probably outdated in parts). We can chat in more
detail if you like as well, feel free to send me a direct mail.
On Wed, Aug 26, 2020 at 6:37 AM 陆亚涵 <ya...@iscas.ac.cn> wrote:
Hi Jakob Gruber ~:
I debug it and found JSEntryTrampoline be called by JSEntry which is be writed
by macroassembler.
It seems always call JSEntryTrampoline through trampoline in JSEntry with or
without the jitless parameter.
发件人: Jakob Gruber
发送时间: 2020年8月25日 18:10
收件人: v8-dev@googlegroups.com
主题: Re: [v8-dev]
Code space is not executable in jitless mode. Instead, builtins are compiled
into the binary, which is where JSEntryTrampoline should be located.
So it sounds to me like either 1. there's an interesting misconfiguration in
your build and you are attempting to jump to the on-heap JSEntryTrampoline code
section; or 2. the embedded builtins section of the binary (the .text section
on linux) is not executable. To be honest, I'd be surprised by either option
but anything is possible.
Given the `address = 0xd3886c5721` from your output above, it sounds like
option 1. In that case, I would investigate where the call to JSEntry is coming
from, and why it doesn't properly jump to the binary-embedded instructions.
Perhaps Invoke?
https://source.chromium.org/chromium/chromium/src/+/master:v8/src/execution/execution.cc;l=241;drc=df4bfabd8b949084fd3c051e23a42c7a11ea83d4
On Tue, Aug 25, 2020 at 11:37 AM 陆亚涵 <ya...@iscas.ac.cn> wrote:
Hi everyone ~
I participate in porting v8 into risc-v(https://github.com/v8-riscv/v8/).
I encount a error about jitless. If i run a helloworld.js with
'--jitless', it occurs SEGV_ACCERR.
error log:
`````
````````````````````````````````````````````````````````````````````````````
$ ./d8 ./test.js --jitless
Warning: unknown flag --enable-slow-asserts.
Try --help for options Received signal 11 SEGV_ACCERR 003fbfe45780
==== C stack trace ===============================
[0x002ac3444ea2]
[0x002ac34455ca]
0x003fc1bb0800]
[0x003fbfe45780]
[end of stack trace]
Segmentation fault (core dumped)
`````
````````````````````````````````````````````````````````````````````````````
address 003fbfe45780 is a Trampoline of builtin function JSEntryTrampoline
`````
````````````````````````````````````````````````````````````````````````````
kind = BUILTIN
name = JSEntryTrampoline
compiler = unknown
address = 0xd3886c5721
Trampoline (size = 36)
0xd3886c5780 0 00000e37 lui t3, 0x0
0xd3886c5784 4 564e0e1b addiw t3, t3, 1380
0xd3886c5788 8 00ce1e13 slli t3, t3, 12
0xd3886c578c c b10e0e13 addi t3, t3, -1264
0xd3886c5790 10 00ce1e13 slli t3, t3, 12
0xd3886c5794 14 503e0e13 addi t3, t3, 1283
0xd3886c5798 18 00ce1e13 slli t3, t3, 12
0xd3886c579c 1c 500e0e13 addi t3, t3, 1280
0xd3886c57a0 20 000e0067 jr t3
`````
````````````````````````````````````````````````````````````````````````````
I found these code leading to it:
```
void SetDefaultCodePermissions() {
if (FLAG_jitless) {
SetReadable();
} else {
SetReadAndExecutable();
}
}
```
But i don't know how to fix it.
Thank you.
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Jakob Gruber
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