libbb: reduce the overhead of single parameter bb_error_msg() calls

Back in 2007, commit 0c97c9d43707 ("'simple' error message functions by
Loic Grenie") introduced bb_simple_perror_msg() to allow for a lower
overhead call to bb_perror_msg() when only a string was being printed
with no parameters. This saves space for some CPU architectures because
it avoids the overhead of a call to a variadic function. However there
has never been a simple version of bb_error_msg(), and since 2007 many
new calls to bb_perror_msg() have been added that only take a single
parameter and so could have been using bb_simple_perror_message().

This changeset introduces 'simple' versions of bb_info_msg(),
bb_error_msg(), bb_error_msg_and_die(), bb_herror_msg() and
bb_herror_msg_and_die(), and replaces all calls that only take a
single parameter, or use something like ("%s", arg), with calls to the
corresponding 'simple' version.

Since it is likely that single parameter calls to the variadic functions
may be accidentally reintroduced in the future a new debugging config
option WARN_SIMPLE_MSG has been introduced. This uses some macro magic
which will cause any such calls to generate a warning, but this is
turned off by default to avoid use of the unpleasant macros in normal
circumstances.

This is a large changeset due to the number of calls that have been
replaced. The only files that contain changes other than simple
substitution of function calls are libbb.h, libbb/herror_msg.c,
libbb/verror_msg.c and libbb/xfuncs_printf.c. In miscutils/devfsd.c,
networking/udhcp/common.h and util-linux/mdev.c additonal macros have
been added for logging so that single parameter and multiple parameter
logging variants exist.

The amount of space saved varies considerably by architecture, and was
found to be as follows (for 'defconfig' using GCC 7.4):

Arm:     -92 bytes
MIPS:    -52 bytes
PPC:   -1836 bytes
x86_64: -938 bytes

Note that for the MIPS architecture only an exception had to be made
disabling the 'simple' calls for 'udhcp' (in networking/udhcp/common.h)
because it made these files larger on MIPS.

Signed-off-by: James Byrne <james.byrne@origamienergy.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 14 insertions, 14 deletions

diff --git a/modutils/modutils-24.c b/modutils/modutils-24.c
index 1a30dd8..ac86324 100644
--- a/modutils/modutils-24.c
+++ b/modutils/modutils-24.c
@@ -2600,7 +2600,7 @@ static void new_get_kernel_symbols(void)
 			module_names = xrealloc(module_names, bufsize);
 			goto retry_modules_load;
 		}
-		bb_perror_msg_and_die("QM_MODULES");
+		bb_simple_perror_msg_and_die("QM_MODULES");
 	}
 
 	n_ext_modules = nmod = ret;
@@ -2661,7 +2661,7 @@ static void new_get_kernel_symbols(void)
 			syms = xrealloc(syms, bufsize);
 			goto retry_kern_sym_load;
 		}
-		bb_perror_msg_and_die("kernel: QM_SYMBOLS");
+		bb_simple_perror_msg_and_die("kernel: QM_SYMBOLS");
 	}
 	nksyms = nsyms = ret;
 	ksyms = syms;
@@ -3247,21 +3247,21 @@ static struct obj_file *obj_load(char *image, size_t image_size, int loadprogbit
 	f->load_order_search_start = &f->load_order;
 
 	if (image_size < sizeof(f->header))
-		bb_error_msg_and_die("error while loading ELF header");
+		bb_simple_error_msg_and_die("error while loading ELF header");
 	memcpy(&f->header, image, sizeof(f->header));
 
 	if (*(aliased_uint32_t*)(&f->header.e_ident) != ELFMAG_U32) {
-		bb_error_msg_and_die("not an ELF file");
+		bb_simple_error_msg_and_die("not an ELF file");
 	}
 	if (f->header.e_ident[EI_CLASS] != ELFCLASSM
 	 || f->header.e_ident[EI_DATA] != (BB_BIG_ENDIAN ? ELFDATA2MSB : ELFDATA2LSB)
 	 || f->header.e_ident[EI_VERSION] != EV_CURRENT
 	 || !MATCH_MACHINE(f->header.e_machine)
 	) {
-		bb_error_msg_and_die("ELF file not for this architecture");
+		bb_simple_error_msg_and_die("ELF file not for this architecture");
 	}
 	if (f->header.e_type != ET_REL) {
-		bb_error_msg_and_die("ELF file not a relocatable object");
+		bb_simple_error_msg_and_die("ELF file not a relocatable object");
 	}
 
 	/* Read the section headers.  */
@@ -3280,7 +3280,7 @@ static struct obj_file *obj_load(char *image, size_t image_size, int loadprogbit
 
 	section_headers = alloca(sizeof(ElfW(Shdr)) * shnum);
 	if (image_size < f->header.e_shoff + sizeof(ElfW(Shdr)) * shnum)
-		bb_error_msg_and_die("error while loading section headers");
+		bb_simple_error_msg_and_die("error while loading section headers");
 	memcpy(section_headers, image + f->header.e_shoff, sizeof(ElfW(Shdr)) * shnum);
 
 	/* Read the section data.  */
@@ -3317,16 +3317,16 @@ static struct obj_file *obj_load(char *image, size_t image_size, int loadprogbit
 				if (sec->header.sh_size > 0) {
 					sec->contents = xmalloc(sec->header.sh_size);
 					if (image_size < (sec->header.sh_offset + sec->header.sh_size))
-						bb_error_msg_and_die("error while loading section data");
+						bb_simple_error_msg_and_die("error while loading section data");
 					memcpy(sec->contents, image + sec->header.sh_offset, sec->header.sh_size);
 				}
 				break;
 #if SHT_RELM == SHT_REL
 			case SHT_RELA:
-				bb_error_msg_and_die("RELA relocations not supported on this architecture");
+				bb_simple_error_msg_and_die("RELA relocations not supported on this architecture");
 #else
 			case SHT_REL:
-				bb_error_msg_and_die("REL relocations not supported on this architecture");
+				bb_simple_error_msg_and_die("REL relocations not supported on this architecture");
 #endif
 			default:
 				if (sec->header.sh_type >= SHT_LOPROC) {
@@ -3447,7 +3447,7 @@ static int obj_load_progbits(char *image, size_t image_size, struct obj_file *f,
 			continue;
 		sec->contents = imagebase + (sec->header.sh_addr - base);
 		if (image_size < (sec->header.sh_offset + sec->header.sh_size)) {
-			bb_error_msg("error reading ELF section data");
+			bb_simple_error_msg("error reading ELF section data");
 			return 0; /* need to delete half-loaded module! */
 		}
 		memcpy(sec->contents, image + sec->header.sh_offset, sec->header.sh_size);
@@ -3845,7 +3845,7 @@ int FAST_FUNC bb_init_module_24(const char *m_filename, const char *options)
 		if (m_has_modinfo) {
 			int m_version = new_get_module_version(f, m_strversion);
 			if (m_version == -1) {
-				bb_error_msg_and_die("can't find the kernel version "
+				bb_simple_error_msg_and_die("can't find the kernel version "
 					"the module was compiled for");
 			}
 		}
@@ -3864,7 +3864,7 @@ int FAST_FUNC bb_init_module_24(const char *m_filename, const char *options)
 #endif
 
 	if (query_module(NULL, 0, NULL, 0, NULL))
-		bb_error_msg_and_die("old (unsupported) kernel");
+		bb_simple_error_msg_and_die("old (unsupported) kernel");
 	new_get_kernel_symbols();
 	k_crcs = new_is_kernel_checksummed();
 
diff --git a/modutils/rmmod.c b/modutils/rmmod.c
index a354887..8d4639f 100644
--- a/modutils/rmmod.c
+++ b/modutils/rmmod.c
@@ -52,7 +52,7 @@ int rmmod_main(int argc UNUSED_PARAM, char **argv)
 		/* Unload _all_ unused modules via NULL delete_module() call */
 		err = bb_delete_module(NULL, flags);
 		if (err && err != EFAULT)
-			bb_perror_msg_and_die("rmmod");
+			bb_simple_perror_msg_and_die("rmmod");
 		return EXIT_SUCCESS;
 	}