Re: [PATCH] newlib: riscv: Add Zicfilp lpads to asm functions

Arjun Salunkhe <[email protected]> Thu, 19 Mar 2026 09:46:37 +0000
Newsgroups	gmane.comp.lib.newlib
Message-ID	<OGIGTD0bOv2-EkheTRKtZV13akEI7lxCr8GuRHZYAm03Eb1iuzx0d6_u094alpjfT_wKJPmWg1jvRG5SmQ1HJPDRGhFGpFzOcbIOVlLxes8=@proton.me>
Thanks for the review! Updated to use __riscv_landing_pad.

From eecb231f5237354fbf67eabb6580f12428177ebf Mon Sep 17 00:00:00 2001
From: Arjun Salunkhe <[email protected]>
Date: Thu, 19 Mar 2026 13:50:54 +0530
Subject: [PATCH v2] newlib: riscv: Add Zicfilp lpads to asm functions

Adds `lpad 0` instructions, guarded by `#if __riscv_landing_pad`,
to the RISC-V assembly memory, setjmp and string functions.

Signed-off-by: Arjun Salunkhe <[email protected]>
---
Changes in v2:
- Use __riscv_landing_pad instead of __riscv_zicfilp

 newlib/libc/machine/riscv/memcpy-asm.S  | 4 ++++
 newlib/libc/machine/riscv/memmove-asm.S | 4 ++++
 newlib/libc/machine/riscv/memset.S      | 4 ++++
 newlib/libc/machine/riscv/setjmp.S      | 6 ++++++
 newlib/libc/machine/riscv/strcmp.S      | 4 ++++
 5 files changed, 22 insertions(+)

diff --git a/newlib/libc/machine/riscv/memcpy-asm.S b/newlib/libc/machine/riscv/memcpy-asm.S
index 2771285f9..136bb4e3a 100644
--- a/newlib/libc/machine/riscv/memcpy-asm.S
+++ b/newlib/libc/machine/riscv/memcpy-asm.S
@@ -14,6 +14,10 @@
 .global memcpy
 .type	memcpy, @function
 memcpy:
+#if __riscv_landing_pad
+  lpad 0
+#endif
+
   mv a3, a0
   beqz a2, 2f
 
diff --git a/newlib/libc/machine/riscv/memmove-asm.S b/newlib/libc/machine/riscv/memmove-asm.S
index 061472ca2..c97b8cb64 100644
--- a/newlib/libc/machine/riscv/memmove-asm.S
+++ b/newlib/libc/machine/riscv/memmove-asm.S
@@ -14,6 +14,10 @@
 .global memmove
 .type	memmove, @function
 memmove:
+#if __riscv_landing_pad
+  lpad 0
+#endif
+
   beqz a2, .Ldone		/* in case there are 0 bytes to be copied, return immediately */
 
   mv a4, a0			/* copy the destination address over to a4, since memmove should return that address in a0 at the end */
diff --git a/newlib/libc/machine/riscv/memset.S b/newlib/libc/machine/riscv/memset.S
index 533f66758..8c3da876c 100644
--- a/newlib/libc/machine/riscv/memset.S
+++ b/newlib/libc/machine/riscv/memset.S
@@ -50,6 +50,10 @@
 
 
 memset:
+#if __riscv_landing_pad
+  lpad 0
+#endif
+
 #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
   mv     a3, a0
   beqz   a2, .Ldone
diff --git a/newlib/libc/machine/riscv/setjmp.S b/newlib/libc/machine/riscv/setjmp.S
index f2b50537e..9cc85e747 100644
--- a/newlib/libc/machine/riscv/setjmp.S
+++ b/newlib/libc/machine/riscv/setjmp.S
@@ -15,6 +15,9 @@
   .globl  setjmp
   .type   setjmp, @function
 setjmp:
+#if __riscv_landing_pad
+  lpad 0
+#endif
 	REG_S ra,  0*SZREG(a0)
   #if __riscv_xlen == 32 && (__riscv_zilsd) && (__riscv_misaligned_fast)
 	  sd    s0,  1*SZREG(a0)
@@ -70,6 +73,9 @@ setjmp:
   .globl  longjmp
   .type   longjmp, @function
 longjmp:
+#if __riscv_landing_pad
+  lpad 0
+#endif
 	REG_L ra,  0*SZREG(a0)
   #if __riscv_xlen == 32 && (__riscv_zilsd) && (__riscv_misaligned_fast)
     ld s0, 1*SZREG(a0)
diff --git a/newlib/libc/machine/riscv/strcmp.S b/newlib/libc/machine/riscv/strcmp.S
index 0b1dfc4b1..18ac9a981 100644
--- a/newlib/libc/machine/riscv/strcmp.S
+++ b/newlib/libc/machine/riscv/strcmp.S
@@ -15,6 +15,10 @@
 .globl strcmp
 .type  strcmp, @function
 strcmp:
+#if __riscv_landing_pad
+  lpad 0
+#endif
+
 #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
 .Lcompare:
   lbu   a2, 0(a0)
-- 
2.53.0


On Thursday, March 19th, 2026 at 2:42 PM, Kito Cheng <[email protected]> wrote:

> Could you check __riscv_landing_pad instead of __riscv_zicfilp? that
> will be defined only if the user enables landing pad gen :)
> 
> ethycS <[email protected]> 於 2026年3月19日週四 下午4:54寫道：
> >
> > From 8ed7d5f2ad33de425a83eff6b1ad4d8c1a0a1108 Mon Sep 17 00:00:00 2001
> > From: Arjun Salunkhe <[email protected]>
> > Date: Thu, 19 Mar 2026 13:50:54 +0530
> > Subject: [PATCH] newlib: riscv: Add Zicfilp lpads to asm functions
> >
> > Adds `lpad 0` instructions, guarded by `#if __riscv_zicfilp`,
> > to the RISC-V assembly memory, setjmp and string functions.
> >
> > Signed-off-by: Arjun Salunkhe <[email protected]>
> > ---
> >  newlib/libc/machine/riscv/memcpy-asm.S  | 4 ++++
> >  newlib/libc/machine/riscv/memmove-asm.S | 4 ++++
> >  newlib/libc/machine/riscv/memset.S      | 4 ++++
> >  newlib/libc/machine/riscv/setjmp.S      | 6 ++++++
> >  newlib/libc/machine/riscv/strcmp.S      | 4 ++++
> >  5 files changed, 22 insertions(+)
> >
> > diff --git a/newlib/libc/machine/riscv/memcpy-asm.S b/newlib/libc/machine/riscv/memcpy-asm.S
> > index 2771285f9..c3d12fca7 100644
> > --- a/newlib/libc/machine/riscv/memcpy-asm.S
> > +++ b/newlib/libc/machine/riscv/memcpy-asm.S
> > @@ -14,6 +14,10 @@
> >  .global memcpy
> >  .type  memcpy, @function
> >  memcpy:
> > +#if __riscv_zicfilp
> > +  lpad 0
> > +#endif
> > +
> >    mv a3, a0
> >    beqz a2, 2f
> >
> > diff --git a/newlib/libc/machine/riscv/memmove-asm.S b/newlib/libc/machine/riscv/memmove-asm.S
> > index 061472ca2..6fb6f6e91 100644
> > --- a/newlib/libc/machine/riscv/memmove-asm.S
> > +++ b/newlib/libc/machine/riscv/memmove-asm.S
> > @@ -14,6 +14,10 @@
> >  .global memmove
> >  .type  memmove, @function
> >  memmove:
> > +#if __riscv_zicfilp
> > +  lpad 0
> > +#endif
> > +
> >    beqz a2, .Ldone              /* in case there are 0 bytes to be copied, return immediately */
> >
> >    mv a4, a0                    /* copy the destination address over to a4, since memmove should return that address in a0 at the end */
> > diff --git a/newlib/libc/machine/riscv/memset.S b/newlib/libc/machine/riscv/memset.S
> > index 533f66758..b922c7b6e 100644
> > --- a/newlib/libc/machine/riscv/memset.S
> > +++ b/newlib/libc/machine/riscv/memset.S
> > @@ -50,6 +50,10 @@
> >
> >
> >  memset:
> > +#if __riscv_zicfilp
> > +  lpad 0
> > +#endif
> > +
> >  #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
> >    mv     a3, a0
> >    beqz   a2, .Ldone
> > diff --git a/newlib/libc/machine/riscv/setjmp.S b/newlib/libc/machine/riscv/setjmp.S
> > index f2b50537e..170928a63 100644
> > --- a/newlib/libc/machine/riscv/setjmp.S
> > +++ b/newlib/libc/machine/riscv/setjmp.S
> > @@ -15,6 +15,9 @@
> >    .globl  setjmp
> >    .type   setjmp, @function
> >  setjmp:
> > +#if __riscv_zicfilp
> > +  lpad 0
> > +#endif
> >         REG_S ra,  0*SZREG(a0)
> >    #if __riscv_xlen == 32 && (__riscv_zilsd) && (__riscv_misaligned_fast)
> >           sd    s0,  1*SZREG(a0)
> > @@ -70,6 +73,9 @@ setjmp:
> >    .globl  longjmp
> >    .type   longjmp, @function
> >  longjmp:
> > +#if __riscv_zicfilp
> > +  lpad 0
> > +#endif
> >         REG_L ra,  0*SZREG(a0)
> >    #if __riscv_xlen == 32 && (__riscv_zilsd) && (__riscv_misaligned_fast)
> >      ld s0, 1*SZREG(a0)
> > diff --git a/newlib/libc/machine/riscv/strcmp.S b/newlib/libc/machine/riscv/strcmp.S
> > index 0b1dfc4b1..e5d75abe9 100644
> > --- a/newlib/libc/machine/riscv/strcmp.S
> > +++ b/newlib/libc/machine/riscv/strcmp.S
> > @@ -15,6 +15,10 @@
> >  .globl strcmp
> >  .type  strcmp, @function
> >  strcmp:
> > +#if __riscv_zicfilp
> > +  lpad 0
> > +#endif
> > +
> >  #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
> >  .Lcompare:
> >    lbu   a2, 0(a0)
> > --
> > 2.53.0
>