[PATCH v3 0/14] Zbb string optimizations and call support in alternatives

[Heiko Stübner]

Am Donnerstag, 1. Dezember 2022, 01:02:08 CET schrieb Conor Dooley:
> On 30/11/2022 22:56, Heiko Stuebner wrote:

> > changes since v2:
> > - add patch fixing the c.jalr funct4 value
> > - reword some commit messages
> > - fix position of auipc addition patch (earlier)
> > - fix compile errors from patch-reordering gone wrong
> >   (worked at the end of v2, but compiling individual patches
> >    caused issues) - patches are now tested individually
> > - limit Zbb variants for GNU as for now
> >   (LLVM support for .option arch is still under review)
> 
> Still no good on that front chief:
> ld.lld: error: undefined symbol: __strlen_generic
> >>> referenced by ctype.c
> >>>               arch/riscv/purgatory/purgatory.ro:(strlcpy)
> >>> referenced by ctype.c
> >>>               arch/riscv/purgatory/purgatory.ro:(strlcat)
> >>> referenced by ctype.c
> >>>               arch/riscv/purgatory/purgatory.ro:(strlcat)
> >>> referenced 3 more times
> make[5]: *** [/stuff/linux/arch/riscv/purgatory/Makefile:85: arch/riscv/purgatory/purgatory.chk] Error 1
> make[5]: Target 'arch/riscv/purgatory/' not remade because of errors.
> make[4]: *** [/stuff/linux/scripts/Makefile.build:500: arch/riscv/purgatory] Error 2

Oh interesting, there is another efistub-like thingy hidden in the tree.
(and CRYPTO_SHA256 needs to be built-in, not a module) to allow the
kexec-purgatory to be build.

The following should do the trick:

---------------- 8< --------------
diff --git a/arch/riscv/include/asm/string.h b/arch/riscv/include/asm/string.h
index 806c402c874e..b99698983045 100644
--- a/arch/riscv/include/asm/string.h
+++ b/arch/riscv/include/asm/string.h
@@ -27,7 +27,7 @@ extern asmlinkage int __strcmp_zbb(const char *cs, const char *ct);
 
 static inline int strcmp(const char *cs, const char *ct)
 {
-#ifdef RISCV_EFISTUB
+#if defined(RISCV_EFISTUB) || defined(RISCV_PURGATORY)
 	return __strcmp_generic(cs, ct);
 #else
 	register const char *a0 asm("a0") = cs;
@@ -55,7 +55,7 @@ extern asmlinkage int __strncmp_zbb(const char *cs,
 
 static inline int strncmp(const char *cs, const char *ct, size_t count)
 {
-#ifdef RISCV_EFISTUB
+#if defined(RISCV_EFISTUB) || defined(RISCV_PURGATORY)
 	return __strncmp_generic(cs, ct, count);
 #else
 	register const char *a0 asm("a0") = cs;
@@ -82,7 +82,7 @@ extern asmlinkage __kernel_size_t __strlen_zbb(const char *);
 
 static inline __kernel_size_t strlen(const char *s)
 {
-#ifdef RISCV_EFISTUB
+#if defined(RISCV_EFISTUB) || defined(RISCV_PURGATORY)
 	return __strlen_generic(s);
 #else
 	register const char *a0 asm("a0") = s;
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile
index dd58e1d99397..1d0969722875 100644
--- a/arch/riscv/purgatory/Makefile
+++ b/arch/riscv/purgatory/Makefile
@@ -2,6 +2,7 @@
 OBJECT_FILES_NON_STANDARD := y
 
 purgatory-y := purgatory.o sha256.o entry.o string.o ctype.o memcpy.o memset.o
+purgatory-y += strcmp.o strlen.o strncmp.o
 
 targets += $(purgatory-y)
 PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y))
@@ -18,6 +19,15 @@ $(obj)/memcpy.o: $(srctree)/arch/riscv/lib/memcpy.S FORCE
 $(obj)/memset.o: $(srctree)/arch/riscv/lib/memset.S FORCE
 	$(call if_changed_rule,as_o_S)
 
+$(obj)/strcmp.o: $(srctree)/arch/riscv/lib/strcmp.S FORCE
+	$(call if_changed_rule,as_o_S)
+
+$(obj)/strlen.o: $(srctree)/arch/riscv/lib/strlen.S FORCE
+	$(call if_changed_rule,as_o_S)
+
+$(obj)/strncmp.o: $(srctree)/arch/riscv/lib/strncmp.S FORCE
+	$(call if_changed_rule,as_o_S)
+
 $(obj)/sha256.o: $(srctree)/lib/crypto/sha256.c FORCE
 	$(call if_changed_rule,cc_o_c)
 
@@ -46,6 +56,7 @@ PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
 PURGATORY_CFLAGS := -mcmodel=medany -ffreestanding -fno-zero-initialized-in-bss
 PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING
 PURGATORY_CFLAGS += -fno-stack-protector -g0
+PURGATORY_CFLAGS += -DRISCV_PURGATORY
 
 # Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
 # in turn leaves some undefined symbols like __fentry__ in purgatory and not
@@ -77,6 +88,9 @@ CFLAGS_ctype.o			+= $(PURGATORY_CFLAGS)
 AFLAGS_REMOVE_entry.o		+= -Wa,-gdwarf-2
 AFLAGS_REMOVE_memcpy.o		+= -Wa,-gdwarf-2
 AFLAGS_REMOVE_memset.o		+= -Wa,-gdwarf-2
+AFLAGS_REMOVE_strcmp.o		+= -Wa,-gdwarf-2
+AFLAGS_REMOVE_strlen.o		+= -Wa,-gdwarf-2
+AFLAGS_REMOVE_strncmp.o		+= -Wa,-gdwarf-2
 
 $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
 		$(call if_changed,ld)