icp: fix rodata being marked as text in x86 Asm code

objtool properly complains that it can't decode some of the
instructions from ICP x86 Asm code. As mentioned in the Makefile,
where those object files were excluded from objtool check (but they
can still be visible under IBT and LTO), those are just constants,
not code.
In that case, they must be placed in .rodata, so they won't be
marked as "allocatable, executable" (ax) in EFL headers and this
effectively prevents objtool from trying to decode this data. That
reveals a whole bunch of other issues in ICP Asm code, as previously
objtool was bailing out after that warning message.

Reviewed-by: Attila Fülöp <attila@fueloep.org>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Closes openzfs#14035

module/Kbuild.in

@@ -150,12 +150,8 @@ $(addprefix $(obj)/icp/,$(ICP_OBJS) $(ICP_OBJS_X86) $(ICP_OBJS_X86_64) \
 $(addprefix $(obj)/icp/,$(ICP_OBJS) $(ICP_OBJS_X86) $(ICP_OBJS_X86_64) \
 	$(ICP_OBJS_ARM64) $(ICP_OBJS_PPC_PPC64)) : ccflags-y += -I$(icp_include)
 
-# Suppress objtool "can't find jump dest instruction at" warnings.  They
-# are caused by the constants which are defined in the text section of the
-# assembly file using .byte instructions (e.g. bswap_mask).  The objtool
-# utility tries to interpret them as opcodes and obviously fails doing so.
+# Suppress objtool "return with modified stack frame" warnings.
 OBJECT_FILES_NON_STANDARD_aesni-gcm-x86_64.o := y
-OBJECT_FILES_NON_STANDARD_ghash-x86_64.o := y
 
 # Suppress objtool "unsupported stack pointer realignment" warnings. We are
 # not using a DRAP register while aligning the stack to a 64 byte boundary.

module/icp/asm-x86_64/modes/aesni-gcm-x86_64.S

@@ -1242,6 +1242,7 @@ atomic_toggle_boolean_nv:
 	RET
 .size	atomic_toggle_boolean_nv,.-atomic_toggle_boolean_nv
 
+.pushsection .rodata
 .align	64
 .Lbswap_mask:
 .byte	15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0
@@ -1255,6 +1256,7 @@ atomic_toggle_boolean_nv:
 .byte	1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
 .byte	65,69,83,45,78,73,32,71,67,77,32,109,111,100,117,108,101,32,102,111,114,32,120,56,54,95,54,52,44,32,67,82,89,80,84,79,71,65,77,83,32,98,121,32,60,97,112,112,114,111,64,111,112,101,110,115,115,108,46,111,114,103,62,0
 .align	64
+.popsection
 
 /* Mark the stack non-executable. */
 #if defined(__linux__) && defined(__ELF__)

module/icp/asm-x86_64/modes/ghash-x86_64.S

@@ -655,6 +655,8 @@ gcm_ghash_avx:
 	RET
 .cfi_endproc
 .size	gcm_ghash_avx,.-gcm_ghash_avx
+
+.pushsection .rodata
 .align	64
 .Lbswap_mask:
 .byte	15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0
@@ -708,6 +710,7 @@ gcm_ghash_avx:
 
 .byte	71,72,65,83,72,32,102,111,114,32,120,56,54,95,54,52,44,32,67,82,89,80,84,79,71,65,77,83,32,98,121,32,60,97,112,112,114,111,64,111,112,101,110,115,115,108,46,111,114,103,62,0
 .align	64
+.popsection
 
 /* Mark the stack non-executable. */
 #if defined(__linux__) && defined(__ELF__)