Thank you. (I just used another email account and forgot to add nickname in
previous email.)
After inspecting the code more deeply, I found another way to fix this bug.
Most functions in tccgen.c ,which modify the vstack , call vcheck_cmp() at
the beginning (like "vsetc" ,"vswap", "vrotb" etc.). but "vpushv" seem to omit
it. So the below patch should also work.
diff --git a/tccgen.c b/tccgen.c
index c36032a..dc6dd9d 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -1473,6 +1473,7 @@ ST_FUNC void vpushv(SValue *v)
{
if (vtop >= vstack + (VSTACK_SIZE - 1))
tcc_error("memory full (vstack)");
+ vcheck_cmp();
vtop++;
*vtop = *v;
}
I prefer latter patch, add vcheck_cmp() just like other vstack-related
functions did.
------------------ Original ------------------
From:
"jullien"
<[email protected]>;
Date: Sat, Jun 19, 2021 10:56 PM
To: "jullien"<[email protected]>;"tinycc-devel"<[email protected]>;
Subject: Re: [Tinycc-devel] Segfault on arm64 when making a function call
with many arguments
All parameters go to the right arguments. So patch looks good
#include <stdio.h>
void map_add(int x0, int x1, int x2, int x3, int x4, int x5, int x6, int x7, in\
t x8) {
printf("%d ", x0);
printf("%d ", x1);
printf("%d ", x2);
printf("%d ", x3);
printf("%d ", x4);
printf("%d ", x5);
printf("%d ", x6);
printf("%d ", x7);
printf("%d ", x8);
}
void main() {
int A = 1;
int B = 2;
map_add(10, 20, 30, 40, 50, 60, 70, 80, A && B);
}
$ tcc foo.c -o foo && ./foo;echo
10 20 30 40 50 60 70 80 1
From: Tinycc-devel [mailto:[email protected]] On
Behalf Of Christian Jullien
Sent: Saturday, June 19, 2021 08:57
To: [email protected]
Subject: Re: [Tinycc-devel] Segfault on arm64 when making a function call with
many arguments
Hi just quickly tested on my RPi arm64.
I don??t know if it works, i.e. all arguments go to the right parameter with
the right value but, at least it no longer segfault.
I??ll make more tests today.
C.
From: Tinycc-devel [mailto:[email protected]] On
Behalf Of pursuer2 via Tinycc-devel
Sent: Saturday, June 19, 2021 08:28
To: jullien; tinycc-devel
Cc: pursuer2
Subject: Re: [Tinycc-devel] Segfault on arm64 when making a function call with
many arguments
This bug may caused by "vpushv" SValue with VT_CMP flag. There should be only
one VT_CMP SValue on vstack.
I make below patch to fix it, then the compilation exit normally. But I
have no arm64 device with GNU/Linux to verify the test.
diff --git a/arm64-gen.c b/arm64-gen.c
index 6389409..a9cbfa2 100644
--- a/arm64-gen.c
+++ b/arm64-gen.c
@@ -1017,6 +1017,9 @@ ST_FUNC void gfunc_call(int nb_args)
if (stack >> 12)
o(0xd14003ff | (stack >>
12) << 10);
+ if((vtop->r&VT_VALMASK)==VT_CMP){
+ gv(RC_INT);
+ }
// First pass: set all values on stack
for (i = nb_args; i; i--) {
vpushv(vtop - nb_args + i);
------------------ Original ------------------
From: "jullien" <[email protected]>;
Date: Fri, Jun 18, 2021 04:04 PM
To: "tinycc-devel"<[email protected]>;
Subject: Re: [Tinycc-devel] Segfault on arm64 when making a function call
with many arguments
I confirm it fails on arm64 (but works on arm 32bits).
It also fails with complete prototype:
void map_add(int a, int b, int c, int d, int e, int f, int g, int h, int i)
{}
C.
From: Tinycc-devel [mailto:[email protected]] On
Behalf Of Arthur Williams
Sent: Wednesday, June 16, 2021 20:18
To: [email protected]
Subject: [Tinycc-devel] Segfault on arm64 when making a function call with many
arguments
Was trying to compile vim with tcc on arm64 but got a segfault. I can simplify
it to the following case:
void map_add(){}
void main() {
int A;
int B;
map_add(0, 0, 0, 0, 0, 0, 0, 0, A && B); // segfaults
when compiling
}
The bad pointer was generated in arm64-gen.c::gsym_addr and the actual segfault
occurred in tcc.h::read16le.
Removing one of the 0s or removing A/B or replacing A && B with a
constant avoids the problem. Cannot repro on x86. I'm running musl on Linux and
using the latest tcc from mob.
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