On Fri, Feb 08, 2019 at 04:23:04PM +0100, Petr Mladek wrote: > We are going to check the address using probe_kernel_address(). It will > be more expensive and it does not make sense for well known address. > > This patch splits the string() function. The variant without the check > is then used on locations that handle string constants or strings defined > as local variables. > > This patch does not change the existing behavior. >
Reviewed-by: Andy Shevchenko <[email protected]> > Signed-off-by: Petr Mladek <[email protected]> > --- > lib/vsprintf.c | 81 > +++++++++++++++++++++++++++++++--------------------------- > 1 file changed, 44 insertions(+), 37 deletions(-) > > diff --git a/lib/vsprintf.c b/lib/vsprintf.c > index 76ce12b278c3..0b6209854f5c 100644 > --- a/lib/vsprintf.c > +++ b/lib/vsprintf.c > @@ -592,15 +592,13 @@ char *widen_string(char *buf, int n, char *end, struct > printf_spec spec) > return buf; > } > > -static noinline_for_stack > -char *string(char *buf, char *end, const char *s, struct printf_spec spec) > +/* Handle string from a well known address. */ > +static char *string_nocheck(char *buf, char *end, const char *s, > + struct printf_spec spec) > { > int len = 0; > size_t lim = spec.precision; > > - if ((unsigned long)s < PAGE_SIZE) > - s = "(null)"; > - > while (lim--) { > char c = *s++; > if (!c) > @@ -614,6 +612,15 @@ char *string(char *buf, char *end, const char *s, struct > printf_spec spec) > } > > static noinline_for_stack > +char *string(char *buf, char *end, const char *s, > + struct printf_spec spec) > +{ > + if ((unsigned long)s < PAGE_SIZE) > + s = "(null)"; > + > + return string_nocheck(buf, end, s, spec); > +} > + > char *pointer_string(char *buf, char *end, const void *ptr, > struct printf_spec spec) > { > @@ -700,7 +707,7 @@ static char *ptr_to_id(char *buf, char *end, const void > *ptr, > if (static_branch_unlikely(¬_filled_random_ptr_key)) { > spec.field_width = 2 * sizeof(ptr); > /* string length must be less than default_width */ > - return string(buf, end, str, spec); > + return string_nocheck(buf, end, str, spec); > } > > #ifdef CONFIG_64BIT > @@ -736,7 +743,7 @@ char *restricted_pointer(char *buf, char *end, const void > *ptr, > if (in_irq() || in_serving_softirq() || in_nmi()) { > if (spec.field_width == -1) > spec.field_width = 2 * sizeof(ptr); > - return string(buf, end, "pK-error", spec); > + return string_nocheck(buf, end, "pK-error", spec); > } > > /* > @@ -850,7 +857,7 @@ char *symbol_string(char *buf, char *end, void *ptr, > else > sprint_symbol_no_offset(sym, value); > > - return string(buf, end, sym, spec); > + return string_nocheck(buf, end, sym, spec); > #else > return special_hex_number(buf, end, value, sizeof(void *)); > #endif > @@ -936,27 +943,27 @@ char *resource_string(char *buf, char *end, struct > resource *res, > > *p++ = '['; > if (res->flags & IORESOURCE_IO) { > - p = string(p, pend, "io ", str_spec); > + p = string_nocheck(p, pend, "io ", str_spec); > specp = &io_spec; > } else if (res->flags & IORESOURCE_MEM) { > - p = string(p, pend, "mem ", str_spec); > + p = string_nocheck(p, pend, "mem ", str_spec); > specp = &mem_spec; > } else if (res->flags & IORESOURCE_IRQ) { > - p = string(p, pend, "irq ", str_spec); > + p = string_nocheck(p, pend, "irq ", str_spec); > specp = &default_dec_spec; > } else if (res->flags & IORESOURCE_DMA) { > - p = string(p, pend, "dma ", str_spec); > + p = string_nocheck(p, pend, "dma ", str_spec); > specp = &default_dec_spec; > } else if (res->flags & IORESOURCE_BUS) { > - p = string(p, pend, "bus ", str_spec); > + p = string_nocheck(p, pend, "bus ", str_spec); > specp = &bus_spec; > } else { > - p = string(p, pend, "??? ", str_spec); > + p = string_nocheck(p, pend, "??? ", str_spec); > specp = &mem_spec; > decode = 0; > } > if (decode && res->flags & IORESOURCE_UNSET) { > - p = string(p, pend, "size ", str_spec); > + p = string_nocheck(p, pend, "size ", str_spec); > p = number(p, pend, resource_size(res), *specp); > } else { > p = number(p, pend, res->start, *specp); > @@ -967,21 +974,21 @@ char *resource_string(char *buf, char *end, struct > resource *res, > } > if (decode) { > if (res->flags & IORESOURCE_MEM_64) > - p = string(p, pend, " 64bit", str_spec); > + p = string_nocheck(p, pend, " 64bit", str_spec); > if (res->flags & IORESOURCE_PREFETCH) > - p = string(p, pend, " pref", str_spec); > + p = string_nocheck(p, pend, " pref", str_spec); > if (res->flags & IORESOURCE_WINDOW) > - p = string(p, pend, " window", str_spec); > + p = string_nocheck(p, pend, " window", str_spec); > if (res->flags & IORESOURCE_DISABLED) > - p = string(p, pend, " disabled", str_spec); > + p = string_nocheck(p, pend, " disabled", str_spec); > } else { > - p = string(p, pend, " flags ", str_spec); > + p = string_nocheck(p, pend, " flags ", str_spec); > p = number(p, pend, res->flags, default_flag_spec); > } > *p++ = ']'; > *p = '\0'; > > - return string(buf, end, sym, spec); > + return string_nocheck(buf, end, sym, spec); > } > > static noinline_for_stack > @@ -1149,7 +1156,7 @@ char *mac_address_string(char *buf, char *end, u8 *addr, > } > *p = '\0'; > > - return string(buf, end, mac_addr, spec); > + return string_nocheck(buf, end, mac_addr, spec); > } > > static noinline_for_stack > @@ -1312,7 +1319,7 @@ char *ip6_addr_string(char *buf, char *end, const u8 > *addr, > else > ip6_string(ip6_addr, addr, fmt); > > - return string(buf, end, ip6_addr, spec); > + return string_nocheck(buf, end, ip6_addr, spec); > } > > static noinline_for_stack > @@ -1323,7 +1330,7 @@ char *ip4_addr_string(char *buf, char *end, const u8 > *addr, > > ip4_string(ip4_addr, addr, fmt); > > - return string(buf, end, ip4_addr, spec); > + return string_nocheck(buf, end, ip4_addr, spec); > } > > static noinline_for_stack > @@ -1385,7 +1392,7 @@ char *ip6_addr_string_sa(char *buf, char *end, const > struct sockaddr_in6 *sa, > } > *p = '\0'; > > - return string(buf, end, ip6_addr, spec); > + return string_nocheck(buf, end, ip6_addr, spec); > } > > static noinline_for_stack > @@ -1420,7 +1427,7 @@ char *ip4_addr_string_sa(char *buf, char *end, const > struct sockaddr_in *sa, > } > *p = '\0'; > > - return string(buf, end, ip4_addr, spec); > + return string_nocheck(buf, end, ip4_addr, spec); > } > > static noinline_for_stack > @@ -1521,7 +1528,7 @@ char *uuid_string(char *buf, char *end, const u8 *addr, > > *p = 0; > > - return string(buf, end, uuid, spec); > + return string_nocheck(buf, end, uuid, spec); > } > > static noinline_for_stack > @@ -1735,13 +1742,13 @@ char *device_node_gen_full_name(const struct > device_node *np, char *buf, char *e > > /* special case for root node */ > if (!parent) > - return string(buf, end, "/", default_str_spec); > + return string_nocheck(buf, end, "/", default_str_spec); > > for (depth = 0; parent->parent; depth++) > parent = parent->parent; > > for ( ; depth >= 0; depth--) { > - buf = string(buf, end, "/", default_str_spec); > + buf = string_nocheck(buf, end, "/", default_str_spec); > buf = string(buf, end, device_node_name_for_depth(np, depth), > default_str_spec); > } > @@ -1769,10 +1776,10 @@ char *device_node_string(char *buf, char *end, struct > device_node *dn, > str_spec.field_width = -1; > > if (!IS_ENABLED(CONFIG_OF)) > - return string(buf, end, "(!OF)", spec); > + return string_nocheck(buf, end, "(!OF)", spec); > > if ((unsigned long)dn < PAGE_SIZE) > - return string(buf, end, "(null)", spec); > + return string_nocheck(buf, end, "(null)", spec); > > /* simple case without anything any more format specifiers */ > fmt++; > @@ -1813,7 +1820,7 @@ char *device_node_string(char *buf, char *end, struct > device_node *dn, > tbuf[2] = of_node_check_flag(dn, OF_POPULATED) ? 'P' : > '-'; > tbuf[3] = of_node_check_flag(dn, OF_POPULATED_BUS) ? > 'B' : '-'; > tbuf[4] = 0; > - buf = string(buf, end, tbuf, str_spec); > + buf = string_nocheck(buf, end, tbuf, str_spec); > break; > case 'c': /* major compatible string */ > ret = of_property_read_string(dn, "compatible", &p); > @@ -1824,10 +1831,10 @@ char *device_node_string(char *buf, char *end, struct > device_node *dn, > has_mult = false; > of_property_for_each_string(dn, "compatible", prop, p) { > if (has_mult) > - buf = string(buf, end, ",", str_spec); > - buf = string(buf, end, "\"", str_spec); > + buf = string_nocheck(buf, end, ",", > str_spec); > + buf = string_nocheck(buf, end, "\"", str_spec); > buf = string(buf, end, p, str_spec); > - buf = string(buf, end, "\"", str_spec); > + buf = string_nocheck(buf, end, "\"", str_spec); > > has_mult = true; > } > @@ -1966,7 +1973,7 @@ char *pointer(const char *fmt, char *buf, char *end, > void *ptr, > */ > if (spec.field_width == -1) > spec.field_width = default_width; > - return string(buf, end, "(null)", spec); > + return string_nocheck(buf, end, "(null)", spec); > } > > switch (*fmt) { > @@ -2022,7 +2029,7 @@ char *pointer(const char *fmt, char *buf, char *end, > void *ptr, > case AF_INET6: > return ip6_addr_string_sa(buf, end, &sa->v6, > spec, fmt); > default: > - return string(buf, end, "(invalid address)", > spec); > + return string_nocheck(buf, end, "(invalid > address)", spec); > }} > } > break; > -- > 2.13.7 > -- With Best Regards, Andy Shevchenko
