Re: [PATCH v10 05/18] powerpc/prom_init: don't use string functions from lib/

[Daniel Axtens]

Hi Christophe,

In trying to extend my KASAN implementation to Book3S 64bit, I found one
other change needed to prom_init. I don't know if you think it should go
in this patch, the next one, or somewhere else entirely - I will leave
it up to you. Just let me know if you want me to carry it separately.

Thanks again for all your work on this and the integration of my series.

Regards,
Daniel

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index 7017156168e8..cebb3fc535ba 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -1265,7 +1265,8 @@ static void __init prom_check_platform_support(void)
                                       "ibm,arch-vec-5-platform-support");
 
        /* First copy the architecture vec template */
-       ibm_architecture_vec = ibm_architecture_vec_template;
+       memcpy(&ibm_architecture_vec, &ibm_architecture_vec_template,
+              sizeof(struct ibm_arch_vec));
 
        if (prop_len > 1) {
                int i;

> When KASAN is active, the string functions in lib/ are doing the
> KASAN checks. This is too early for prom_init.
>
> This patch implements dedicated string functions for prom_init,
> which will be compiled in with KASAN disabled.
>
> Size of prom_init before the patch:
>    text	   data	    bss	    dec	    hex	filename
>   12060	    488	   6960	  19508	   4c34	arch/powerpc/kernel/prom_init.o
>
> Size of prom_init after the patch:
>    text	   data	    bss	    dec	    hex	filename
>   12460	    488	   6960	  19908	   4dc4	arch/powerpc/kernel/prom_init.o
>
> This increases the size of prom_init a bit, but as prom_init is
> in __init section, it is freed after boot anyway.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
> ---
>  arch/powerpc/kernel/prom_init.c        | 211 ++++++++++++++++++++++++++-------
>  arch/powerpc/kernel/prom_init_check.sh |   2 +-
>  2 files changed, 171 insertions(+), 42 deletions(-)
>
> diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
> index ecf083c46bdb..7017156168e8 100644
> --- a/arch/powerpc/kernel/prom_init.c
> +++ b/arch/powerpc/kernel/prom_init.c
> @@ -224,6 +224,135 @@ static bool  __prombss rtas_has_query_cpu_stopped;
>  #define PHANDLE_VALID(p)	((p) != 0 && (p) != PROM_ERROR)
>  #define IHANDLE_VALID(i)	((i) != 0 && (i) != PROM_ERROR)
>  
> +/* Copied from lib/string.c and lib/kstrtox.c */
> +
> +static int __init prom_strcmp(const char *cs, const char *ct)
> +{
> +	unsigned char c1, c2;
> +
> +	while (1) {
> +		c1 = *cs++;
> +		c2 = *ct++;
> +		if (c1 != c2)
> +			return c1 < c2 ? -1 : 1;
> +		if (!c1)
> +			break;
> +	}
> +	return 0;
> +}
> +
> +static char __init *prom_strcpy(char *dest, const char *src)
> +{
> +	char *tmp = dest;
> +
> +	while ((*dest++ = *src++) != '\0')
> +		/* nothing */;
> +	return tmp;
> +}
> +
> +static int __init prom_strncmp(const char *cs, const char *ct, size_t count)
> +{
> +	unsigned char c1, c2;
> +
> +	while (count) {
> +		c1 = *cs++;
> +		c2 = *ct++;
> +		if (c1 != c2)
> +			return c1 < c2 ? -1 : 1;
> +		if (!c1)
> +			break;
> +		count--;
> +	}
> +	return 0;
> +}
> +
> +static size_t __init prom_strlen(const char *s)
> +{
> +	const char *sc;
> +
> +	for (sc = s; *sc != '\0'; ++sc)
> +		/* nothing */;
> +	return sc - s;
> +}
> +
> +static int __init prom_memcmp(const void *cs, const void *ct, size_t count)
> +{
> +	const unsigned char *su1, *su2;
> +	int res = 0;
> +
> +	for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
> +		if ((res = *su1 - *su2) != 0)
> +			break;
> +	return res;
> +}
> +
> +static char __init *prom_strstr(const char *s1, const char *s2)
> +{
> +	size_t l1, l2;
> +
> +	l2 = prom_strlen(s2);
> +	if (!l2)
> +		return (char *)s1;
> +	l1 = prom_strlen(s1);
> +	while (l1 >= l2) {
> +		l1--;
> +		if (!prom_memcmp(s1, s2, l2))
> +			return (char *)s1;
> +		s1++;
> +	}
> +	return NULL;
> +}
> +
> +static size_t __init prom_strlcpy(char *dest, const char *src, size_t size)
> +{
> +	size_t ret = prom_strlen(src);
> +
> +	if (size) {
> +		size_t len = (ret >= size) ? size - 1 : ret;
> +		memcpy(dest, src, len);
> +		dest[len] = '\0';
> +	}
> +	return ret;
> +}
> +
> +#ifdef CONFIG_PPC_PSERIES
> +static int __init prom_strtobool(const char *s, bool *res)
> +{
> +	if (!s)
> +		return -EINVAL;
> +
> +	switch (s[0]) {
> +	case 'y':
> +	case 'Y':
> +	case '1':
> +		*res = true;
> +		return 0;
> +	case 'n':
> +	case 'N':
> +	case '0':
> +		*res = false;
> +		return 0;
> +	case 'o':
> +	case 'O':
> +		switch (s[1]) {
> +		case 'n':
> +		case 'N':
> +			*res = true;
> +			return 0;
> +		case 'f':
> +		case 'F':
> +			*res = false;
> +			return 0;
> +		default:
> +			break;
> +		}
> +	default:
> +		break;
> +	}
> +
> +	return -EINVAL;
> +}
> +#endif
>  
>  /* This is the one and *ONLY* place where we actually call open
>   * firmware.
> @@ -555,7 +684,7 @@ static int __init prom_setprop(phandle node, const char *nodename,
>  	add_string(&p, tohex((u32)(unsigned long) value));
>  	add_string(&p, tohex(valuelen));
>  	add_string(&p, tohex(ADDR(pname)));
> -	add_string(&p, tohex(strlen(pname)));
> +	add_string(&p, tohex(prom_strlen(pname)));
>  	add_string(&p, "property");
>  	*p = 0;
>  	return call_prom("interpret", 1, 1, (u32)(unsigned long) cmd);
> @@ -638,23 +767,23 @@ static void __init early_cmdline_parse(void)
>  	if ((long)prom.chosen > 0)
>  		l = prom_getprop(prom.chosen, "bootargs", p, COMMAND_LINE_SIZE-1);
>  	if (IS_ENABLED(CONFIG_CMDLINE_BOOL) && (l <= 0 || p[0] == '\0')) /* dbl check */
> -		strlcpy(prom_cmd_line, CONFIG_CMDLINE, sizeof(prom_cmd_line));
> +		prom_strlcpy(prom_cmd_line, CONFIG_CMDLINE, sizeof(prom_cmd_line));
>  	prom_printf("command line: %s\n", prom_cmd_line);
>  
>  #ifdef CONFIG_PPC64
> -	opt = strstr(prom_cmd_line, "iommu=");
> +	opt = prom_strstr(prom_cmd_line, "iommu=");
>  	if (opt) {
>  		prom_printf("iommu opt is: %s\n", opt);
>  		opt += 6;
>  		while (*opt && *opt == ' ')
>  			opt++;
> -		if (!strncmp(opt, "off", 3))
> +		if (!prom_strncmp(opt, "off", 3))
>  			prom_iommu_off = 1;
> -		else if (!strncmp(opt, "force", 5))
> +		else if (!prom_strncmp(opt, "force", 5))
>  			prom_iommu_force_on = 1;
>  	}
>  #endif
> -	opt = strstr(prom_cmd_line, "mem=");
> +	opt = prom_strstr(prom_cmd_line, "mem=");
>  	if (opt) {
>  		opt += 4;
>  		prom_memory_limit = prom_memparse(opt, (const char **)&opt);
> @@ -666,13 +795,13 @@ static void __init early_cmdline_parse(void)
>  
>  #ifdef CONFIG_PPC_PSERIES
>  	prom_radix_disable = !IS_ENABLED(CONFIG_PPC_RADIX_MMU_DEFAULT);
> -	opt = strstr(prom_cmd_line, "disable_radix");
> +	opt = prom_strstr(prom_cmd_line, "disable_radix");
>  	if (opt) {
>  		opt += 13;
>  		if (*opt && *opt == '=') {
>  			bool val;
>  
> -			if (kstrtobool(++opt, &val))
> +			if (prom_strtobool(++opt, &val))
>  				prom_radix_disable = false;
>  			else
>  				prom_radix_disable = val;
> @@ -1025,7 +1154,7 @@ static int __init prom_count_smt_threads(void)
>  		type[0] = 0;
>  		prom_getprop(node, "device_type", type, sizeof(type));
>  
> -		if (strcmp(type, "cpu"))
> +		if (prom_strcmp(type, "cpu"))
>  			continue;
>  		/*
>  		 * There is an entry for each smt thread, each entry being
> @@ -1472,7 +1601,7 @@ static void __init prom_init_mem(void)
>  			 */
>  			prom_getprop(node, "name", type, sizeof(type));
>  		}
> -		if (strcmp(type, "memory"))
> +		if (prom_strcmp(type, "memory"))
>  			continue;
>  
>  		plen = prom_getprop(node, "reg", regbuf, sizeof(regbuf));
> @@ -1753,19 +1882,19 @@ static void __init prom_initialize_tce_table(void)
>  		prom_getprop(node, "device_type", type, sizeof(type));
>  		prom_getprop(node, "model", model, sizeof(model));
>  
> -		if ((type[0] == 0) || (strstr(type, "pci") == NULL))
> +		if ((type[0] == 0) || (prom_strstr(type, "pci") == NULL))
>  			continue;
>  
>  		/* Keep the old logic intact to avoid regression. */
>  		if (compatible[0] != 0) {
> -			if ((strstr(compatible, "python") == NULL) &&
> -			    (strstr(compatible, "Speedwagon") == NULL) &&
> -			    (strstr(compatible, "Winnipeg") == NULL))
> +			if ((prom_strstr(compatible, "python") == NULL) &&
> +			    (prom_strstr(compatible, "Speedwagon") == NULL) &&
> +			    (prom_strstr(compatible, "Winnipeg") == NULL))
>  				continue;
>  		} else if (model[0] != 0) {
> -			if ((strstr(model, "ython") == NULL) &&
> -			    (strstr(model, "peedwagon") == NULL) &&
> -			    (strstr(model, "innipeg") == NULL))
> +			if ((prom_strstr(model, "ython") == NULL) &&
> +			    (prom_strstr(model, "peedwagon") == NULL) &&
> +			    (prom_strstr(model, "innipeg") == NULL))
>  				continue;
>  		}
>  
> @@ -1914,12 +2043,12 @@ static void __init prom_hold_cpus(void)
>  
>  		type[0] = 0;
>  		prom_getprop(node, "device_type", type, sizeof(type));
> -		if (strcmp(type, "cpu") != 0)
> +		if (prom_strcmp(type, "cpu") != 0)
>  			continue;
>  
>  		/* Skip non-configured cpus. */
>  		if (prom_getprop(node, "status", type, sizeof(type)) > 0)
> -			if (strcmp(type, "okay") != 0)
> +			if (prom_strcmp(type, "okay") != 0)
>  				continue;
>  
>  		reg = cpu_to_be32(-1); /* make sparse happy */
> @@ -1995,9 +2124,9 @@ static void __init prom_find_mmu(void)
>  		return;
>  	version[sizeof(version) - 1] = 0;
>  	/* XXX might need to add other versions here */
> -	if (strcmp(version, "Open Firmware, 1.0.5") == 0)
> +	if (prom_strcmp(version, "Open Firmware, 1.0.5") == 0)
>  		of_workarounds = OF_WA_CLAIM;
> -	else if (strncmp(version, "FirmWorks,3.", 12) == 0) {
> +	else if (prom_strncmp(version, "FirmWorks,3.", 12) == 0) {
>  		of_workarounds = OF_WA_CLAIM | OF_WA_LONGTRAIL;
>  		call_prom("interpret", 1, 1, "dev /memory 0 to allow-reclaim");
>  	} else
> @@ -2030,7 +2159,7 @@ static void __init prom_init_stdout(void)
>  	call_prom("instance-to-path", 3, 1, prom.stdout, path, 255);
>  	prom_printf("OF stdout device is: %s\n", of_stdout_device);
>  	prom_setprop(prom.chosen, "/chosen", "linux,stdout-path",
> -		     path, strlen(path) + 1);
> +		     path, prom_strlen(path) + 1);
>  
>  	/* instance-to-package fails on PA-Semi */
>  	stdout_node = call_prom("instance-to-package", 1, 1, prom.stdout);
> @@ -2040,7 +2169,7 @@ static void __init prom_init_stdout(void)
>  		/* If it's a display, note it */
>  		memset(type, 0, sizeof(type));
>  		prom_getprop(stdout_node, "device_type", type, sizeof(type));
> -		if (strcmp(type, "display") == 0)
> +		if (prom_strcmp(type, "display") == 0)
>  			prom_setprop(stdout_node, path, "linux,boot-display", NULL, 0);
>  	}
>  }
> @@ -2061,19 +2190,19 @@ static int __init prom_find_machine_type(void)
>  		compat[len] = 0;
>  		while (i < len) {
>  			char *p = &compat[i];
> -			int sl = strlen(p);
> +			int sl = prom_strlen(p);
>  			if (sl == 0)
>  				break;
> -			if (strstr(p, "Power Macintosh") ||
> -			    strstr(p, "MacRISC"))
> +			if (prom_strstr(p, "Power Macintosh") ||
> +			    prom_strstr(p, "MacRISC"))
>  				return PLATFORM_POWERMAC;
>  #ifdef CONFIG_PPC64
>  			/* We must make sure we don't detect the IBM Cell
>  			 * blades as pSeries due to some firmware issues,
>  			 * so we do it here.
>  			 */
> -			if (strstr(p, "IBM,CBEA") ||
> -			    strstr(p, "IBM,CPBW-1.0"))
> +			if (prom_strstr(p, "IBM,CBEA") ||
> +			    prom_strstr(p, "IBM,CPBW-1.0"))
>  				return PLATFORM_GENERIC;
>  #endif /* CONFIG_PPC64 */
>  			i += sl + 1;
> @@ -2090,7 +2219,7 @@ static int __init prom_find_machine_type(void)
>  			   compat, sizeof(compat)-1);
>  	if (len <= 0)
>  		return PLATFORM_GENERIC;
> -	if (strcmp(compat, "chrp"))
> +	if (prom_strcmp(compat, "chrp"))
>  		return PLATFORM_GENERIC;
>  
>  	/* Default to pSeries. We need to know if we are running LPAR */
> @@ -2152,7 +2281,7 @@ static void __init prom_check_displays(void)
>  	for (node = 0; prom_next_node(&node); ) {
>  		memset(type, 0, sizeof(type));
>  		prom_getprop(node, "device_type", type, sizeof(type));
> -		if (strcmp(type, "display") != 0)
> +		if (prom_strcmp(type, "display") != 0)
>  			continue;
>  
>  		/* It seems OF doesn't null-terminate the path :-( */
> @@ -2256,9 +2385,9 @@ static unsigned long __init dt_find_string(char *str)
>  	s = os = (char *)dt_string_start;
>  	s += 4;
>  	while (s <  (char *)dt_string_end) {
> -		if (strcmp(s, str) == 0)
> +		if (prom_strcmp(s, str) == 0)
>  			return s - os;
> -		s += strlen(s) + 1;
> +		s += prom_strlen(s) + 1;
>  	}
>  	return 0;
>  }
> @@ -2291,7 +2420,7 @@ static void __init scan_dt_build_strings(phandle node,
>  		}
>  
>   		/* skip "name" */
> - 		if (strcmp(namep, "name") == 0) {
> +		if (prom_strcmp(namep, "name") == 0) {
>   			*mem_start = (unsigned long)namep;
>   			prev_name = "name";
>   			continue;
> @@ -2303,7 +2432,7 @@ static void __init scan_dt_build_strings(phandle node,
>  			namep = sstart + soff;
>  		} else {
>  			/* Trim off some if we can */
> -			*mem_start = (unsigned long)namep + strlen(namep) + 1;
> +			*mem_start = (unsigned long)namep + prom_strlen(namep) + 1;
>  			dt_string_end = *mem_start;
>  		}
>  		prev_name = namep;
> @@ -2372,7 +2501,7 @@ static void __init scan_dt_build_struct(phandle node, unsigned long *mem_start,
>  			break;
>  
>   		/* skip "name" */
> - 		if (strcmp(pname, "name") == 0) {
> +		if (prom_strcmp(pname, "name") == 0) {
>   			prev_name = "name";
>   			continue;
>   		}
> @@ -2403,7 +2532,7 @@ static void __init scan_dt_build_struct(phandle node, unsigned long *mem_start,
>  		call_prom("getprop", 4, 1, node, pname, valp, l);
>  		*mem_start = _ALIGN(*mem_start, 4);
>  
> -		if (!strcmp(pname, "phandle"))
> +		if (!prom_strcmp(pname, "phandle"))
>  			has_phandle = 1;
>  	}
>  
> @@ -2473,8 +2602,8 @@ static void __init flatten_device_tree(void)
>  
>  	/* Add "phandle" in there, we'll need it */
>  	namep = make_room(&mem_start, &mem_end, 16, 1);
> -	strcpy(namep, "phandle");
> -	mem_start = (unsigned long)namep + strlen(namep) + 1;
> +	prom_strcpy(namep, "phandle");
> +	mem_start = (unsigned long)namep + prom_strlen(namep) + 1;
>  
>  	/* Build string array */
>  	prom_printf("Building dt strings...\n"); 
> @@ -2796,7 +2925,7 @@ static void __init fixup_device_tree_efika(void)
>  	rv = prom_getprop(node, "model", prop, sizeof(prop));
>  	if (rv == PROM_ERROR)
>  		return;
> -	if (strcmp(prop, "EFIKA5K2"))
> +	if (prom_strcmp(prop, "EFIKA5K2"))
>  		return;
>  
>  	prom_printf("Applying EFIKA device tree fixups\n");
> @@ -2804,13 +2933,13 @@ static void __init fixup_device_tree_efika(void)
>  	/* Claiming to be 'chrp' is death */
>  	node = call_prom("finddevice", 1, 1, ADDR("/"));
>  	rv = prom_getprop(node, "device_type", prop, sizeof(prop));
> -	if (rv != PROM_ERROR && (strcmp(prop, "chrp") == 0))
> +	if (rv != PROM_ERROR && (prom_strcmp(prop, "chrp") == 0))
>  		prom_setprop(node, "/", "device_type", "efika", sizeof("efika"));
>  
>  	/* CODEGEN,description is exposed in /proc/cpuinfo so
>  	   fix that too */
>  	rv = prom_getprop(node, "CODEGEN,description", prop, sizeof(prop));
> -	if (rv != PROM_ERROR && (strstr(prop, "CHRP")))
> +	if (rv != PROM_ERROR && (prom_strstr(prop, "CHRP")))
>  		prom_setprop(node, "/", "CODEGEN,description",
>  			     "Efika 5200B PowerPC System",
>  			     sizeof("Efika 5200B PowerPC System"));
> diff --git a/arch/powerpc/kernel/prom_init_check.sh b/arch/powerpc/kernel/prom_init_check.sh
> index 181fd10008ef..4cac45cb5de5 100644
> --- a/arch/powerpc/kernel/prom_init_check.sh
> +++ b/arch/powerpc/kernel/prom_init_check.sh
> @@ -27,7 +27,7 @@ fi
>  WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
>  _end enter_prom $MEM_FUNCS reloc_offset __secondary_hold
>  __secondary_hold_acknowledge __secondary_hold_spinloop __start
> -strcmp strcpy strlcpy strlen strncmp strstr kstrtobool logo_linux_clut224
> +logo_linux_clut224
>  reloc_got2 kernstart_addr memstart_addr linux_banner _stext
>  __prom_init_toc_start __prom_init_toc_end btext_setup_display TOC."
>  
> -- 
> 2.13.3