Signed-off-by: Vineet Gupta <vgupta@synopsys.com> --- libc/sysdeps/linux/arc/crt1.S | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/libc/sysdeps/linux/arc/crt1.S b/libc/sysdeps/linux/arc/crt1.S index 95c41f888850..e38c8e81b2c0 100644 --- a/libc/sysdeps/linux/arc/crt1.S +++ b/libc/sysdeps/linux/arc/crt1.S @@ -41,11 +41,15 @@ __start: mov_s r5, r0 ; rltd_fini add_s r2, sp, 4 ; argv - +#ifdef L_Scrt1 + add r0, pcl, @main@pcl + add r3, pcl, @_init@pcl + add r4, pcl, @_fini@pcl +#else mov_s r0, main mov_s r3, _init mov r4, _fini - +#endif and sp, sp, -8 mov r6, sp -- 2.5.0
Hi Vineet, Vineet Gupta wrote,
Signed-off-by: Vineet Gupta <vgupta@synopsys.com> --- libc/sysdeps/linux/arc/crt1.S | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/libc/sysdeps/linux/arc/crt1.S b/libc/sysdeps/linux/arc/crt1.S index 95c41f888850..e38c8e81b2c0 100644 --- a/libc/sysdeps/linux/arc/crt1.S +++ b/libc/sysdeps/linux/arc/crt1.S @@ -41,11 +41,15 @@ __start:
mov_s r5, r0 ; rltd_fini add_s r2, sp, 4 ; argv - +#ifdef L_Scrt1 + add r0, pcl, @main@pcl + add r3, pcl, @_init@pcl + add r4, pcl, @_fini@pcl +#else mov_s r0, main mov_s r3, _init mov r4, _fini - +#endif and sp, sp, -8 mov r6, sp
Can you please be a little more descriptive why this patch is useful? Will ARC support static PIE or is Scrt1.o used in other code? best regards Waldemar Sorry, had to resend with correct sender address.
On Wednesday 15 June 2016 08:34 PM, Waldemar Brodkorb wrote:
Hi Vineet, Vineet Gupta wrote,
Signed-off-by: Vineet Gupta <vgupta@synopsys.com> --- libc/sysdeps/linux/arc/crt1.S | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/libc/sysdeps/linux/arc/crt1.S b/libc/sysdeps/linux/arc/crt1.S index 95c41f888850..e38c8e81b2c0 100644 --- a/libc/sysdeps/linux/arc/crt1.S +++ b/libc/sysdeps/linux/arc/crt1.S @@ -41,11 +41,15 @@ __start:
mov_s r5, r0 ; rltd_fini add_s r2, sp, 4 ; argv - +#ifdef L_Scrt1 + add r0, pcl, @main@pcl + add r3, pcl, @_init@pcl + add r4, pcl, @_fini@pcl +#else mov_s r0, main mov_s r3, _init mov r4, _fini - +#endif and sp, sp, -8 mov r6, sp Can you please be a little more descriptive why this patch is useful? Will ARC support static PIE or is Scrt1.o used in other code?
This is for a dynamically linked PIE - can we have static linked PIE ? Current approach of taking addresses of functions, in not position independent but still works for the normal dynamically linked executables (non PIE) since the zero based addresses are rightly resolved in final link. This is not true for PIE hence we need a really position independent way (PC relative addr) to pass those function addresses. Do u want me to respin with beefed up changelog.
Sorry, had to resend with correct sender address.
My address was wrong ?
Hi Vineet, Vineet Gupta wrote,
On Wednesday 15 June 2016 08:34 PM, Waldemar Brodkorb wrote:
Hi Vineet, Vineet Gupta wrote,
Signed-off-by: Vineet Gupta <vgupta@synopsys.com> --- libc/sysdeps/linux/arc/crt1.S | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/libc/sysdeps/linux/arc/crt1.S b/libc/sysdeps/linux/arc/crt1.S index 95c41f888850..e38c8e81b2c0 100644 --- a/libc/sysdeps/linux/arc/crt1.S +++ b/libc/sysdeps/linux/arc/crt1.S @@ -41,11 +41,15 @@ __start:
mov_s r5, r0 ; rltd_fini add_s r2, sp, 4 ; argv - +#ifdef L_Scrt1 + add r0, pcl, @main@pcl + add r3, pcl, @_init@pcl + add r4, pcl, @_fini@pcl +#else mov_s r0, main mov_s r3, _init mov r4, _fini - +#endif and sp, sp, -8 mov r6, sp Can you please be a little more descriptive why this patch is useful? Will ARC support static PIE or is Scrt1.o used in other code?
This is for a dynamically linked PIE - can we have static linked PIE ? Current approach of taking addresses of functions, in not position independent but still works for the normal dynamically linked executables (non PIE) since the zero based addresses are rightly resolved in final link. This is not true for PIE hence we need a really position independent way (PC relative addr) to pass those function addresses.
You can try static PIE with binutils 2.26 and up with -Wl,--no-dynamic-linker, but my tests with ARM/MIPS failed. So I am not sure if crt1.S is the problem or something else.
Do u want me to respin with beefed up changelog.
Yes, please.
Sorry, had to resend with correct sender address.
My address was wrong ?
No, I use mutt and I am to lazy to configure send-hooks, so I manually change my mail address before sending e-Mails :/ best regards Waldemar
On Thu, Jun 16, 2016 at 09:49:10PM +0200, Waldemar Brodkorb wrote:
Hi Vineet, Vineet Gupta wrote,
On Wednesday 15 June 2016 08:34 PM, Waldemar Brodkorb wrote:
Hi Vineet, Vineet Gupta wrote,
Signed-off-by: Vineet Gupta <vgupta@synopsys.com> --- libc/sysdeps/linux/arc/crt1.S | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/libc/sysdeps/linux/arc/crt1.S b/libc/sysdeps/linux/arc/crt1.S index 95c41f888850..e38c8e81b2c0 100644 --- a/libc/sysdeps/linux/arc/crt1.S +++ b/libc/sysdeps/linux/arc/crt1.S @@ -41,11 +41,15 @@ __start:
mov_s r5, r0 ; rltd_fini add_s r2, sp, 4 ; argv - +#ifdef L_Scrt1 + add r0, pcl, @main@pcl + add r3, pcl, @_init@pcl + add r4, pcl, @_fini@pcl +#else mov_s r0, main mov_s r3, _init mov r4, _fini - +#endif and sp, sp, -8 mov r6, sp Can you please be a little more descriptive why this patch is useful? Will ARC support static PIE or is Scrt1.o used in other code?
This is for a dynamically linked PIE - can we have static linked PIE ? Current approach of taking addresses of functions, in not position independent but still works for the normal dynamically linked executables (non PIE) since the zero based addresses are rightly resolved in final link. This is not true for PIE hence we need a really position independent way (PC relative addr) to pass those function addresses.
You can try static PIE with binutils 2.26 and up with -Wl,--no-dynamic-linker, but my tests with ARM/MIPS failed. So I am not sure if crt1.S is the problem or something else.
Static PIE requires an rcrt1.o that's responsible for performing self-relocation equivalent to what the dynamic linker does to itself. Scrt1.o is for dynamic-linker PIE (and it's compatible with linking in non-PIE code whether it's static or dynamic linked, but not necessary in those cases). Rich
Currently crt1 takes address of functions (main,_init,_fini) directly which doesn't generate truely position independent code, but zero based values instead. e.g. | __start: | ... | add_s r2,sp,0x4 | mov_s r0, main generates to | 000156ec <__start>: | ... | 156f4: add_s r2,sp,0x4 | 156f6: mov_s r0,0x15f7c | ... | 00015f7c <main>: | 15f7c: push_s blink This works just fine for the normal (non PIE) dynamic executables since they are loaded at address 0. However this is not true for PIE executables. So for Scrt1 we use a true position independent way when taking function addresses. Cc: uclibc@uclibc.org <uclibc@uclibc.org> Cc: devel@uclibc-ng.org <devel@uclibc-ng.org> Cc: Cupertino Miranda <cmiranda@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> --- libc/sysdeps/linux/arc/crt1.S | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/libc/sysdeps/linux/arc/crt1.S b/libc/sysdeps/linux/arc/crt1.S index 95c41f888850..e38c8e81b2c0 100644 --- a/libc/sysdeps/linux/arc/crt1.S +++ b/libc/sysdeps/linux/arc/crt1.S @@ -41,11 +41,15 @@ __start: mov_s r5, r0 ; rltd_fini add_s r2, sp, 4 ; argv - +#ifdef L_Scrt1 + add r0, pcl, @main@pcl + add r3, pcl, @_init@pcl + add r4, pcl, @_fini@pcl +#else mov_s r0, main mov_s r3, _init mov r4, _fini - +#endif and sp, sp, -8 mov r6, sp -- 2.5.0
Hi Vineet, Vineet Gupta wrote,
Currently crt1 takes address of functions (main,_init,_fini) directly which doesn't generate truely position independent code, but zero based values instead. e.g.
| __start: | ... | add_s r2,sp,0x4 | mov_s r0, main
generates to
| 000156ec <__start>: | ... | 156f4: add_s r2,sp,0x4 | 156f6: mov_s r0,0x15f7c | ... | 00015f7c <main>: | 15f7c: push_s blink
This works just fine for the normal (non PIE) dynamic executables since they are loaded at address 0. However this is not true for PIE executables. So for Scrt1 we use a true position independent way when taking function addresses.
Cc: uclibc@uclibc.org <uclibc@uclibc.org> Cc: devel@uclibc-ng.org <devel@uclibc-ng.org> Cc: Cupertino Miranda <cmiranda@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> --- libc/sysdeps/linux/arc/crt1.S | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
Applied and pushed, thx Waldemar
Hi Vineet, Vineet Gupta wrote, ping? (resend with better changelog)
On Wednesday 15 June 2016 08:34 PM, Waldemar Brodkorb wrote:
Hi Vineet, Vineet Gupta wrote,
Signed-off-by: Vineet Gupta <vgupta@synopsys.com> --- libc/sysdeps/linux/arc/crt1.S | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/libc/sysdeps/linux/arc/crt1.S b/libc/sysdeps/linux/arc/crt1.S index 95c41f888850..e38c8e81b2c0 100644 --- a/libc/sysdeps/linux/arc/crt1.S +++ b/libc/sysdeps/linux/arc/crt1.S @@ -41,11 +41,15 @@ __start:
mov_s r5, r0 ; rltd_fini add_s r2, sp, 4 ; argv - +#ifdef L_Scrt1 + add r0, pcl, @main@pcl + add r3, pcl, @_init@pcl + add r4, pcl, @_fini@pcl +#else mov_s r0, main mov_s r3, _init mov r4, _fini - +#endif and sp, sp, -8 mov r6, sp Can you please be a little more descriptive why this patch is useful? Will ARC support static PIE or is Scrt1.o used in other code?
This is for a dynamically linked PIE - can we have static linked PIE ? Current approach of taking addresses of functions, in not position independent but still works for the normal dynamically linked executables (non PIE) since the zero based addresses are rightly resolved in final link. This is not true for PIE hence we need a really position independent way (PC relative addr) to pass those function addresses.
Do u want me to respin with beefed up changelog.
Sorry, had to resend with correct sender address.
My address was wrong ?
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participants (3)
-
Rich Felker -
Vineet Gupta -
Waldemar Brodkorb