diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index 75d2bbe9813f..dffd5c0b24f8 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -79,6 +79,18 @@ has the added benefit of providing a unique identifier. On 64-bit machines
the first 32 bits are zeroed. The kernel will print ``(ptrval)`` until it
gathers enough entropy. If you *really* want the address see %px below.
+Error Pointers
+--------------
+
+::
+
+ %pe -ENOSPC
+
+For printing error pointers (i.e. a pointer for which IS_ERR() is true)
+as a symbolic error name. Error values for which no symbolic name is
+known are printed in decimal, while a non-ERR_PTR passed as the
+argument to %pe gets treated as ordinary %p.
+
Symbols/Function Pointers
-------------------------
diff --git a/include/linux/errname.h b/include/linux/errname.h
new file mode 100644
index 000000000000..e8576ad90cb7
--- /dev/null
+++ b/include/linux/errname.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_ERRNAME_H
+#define _LINUX_ERRNAME_H
+
+#include <linux/stddef.h>
+
+#ifdef CONFIG_SYMBOLIC_ERRNAME
+const char *errname(int err);
+#else
+static inline const char *errname(int err)
+{
+ return NULL;
+}
+#endif
+
+#endif /* _LINUX_ERRNAME_H */
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 06d9c9d70385..4934b69c7b39 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -164,6 +164,15 @@ config DYNAMIC_DEBUG
See Documentation/admin-guide/dynamic-debug-howto.rst for additional
information.
+config SYMBOLIC_ERRNAME
+ bool "Support symbolic error names in printf"
+ default y if PRINTK
+ help
+ If you say Y here, the kernel's printf implementation will
+ be able to print symbolic error names such as ENOSPC instead
+ of the number 28. It makes the kernel image slightly larger
+ (about 3KB), but can make the kernel logs easier to read.
+
endmenu # "printk and dmesg options"
menu "Compile-time checks and compiler options"
diff --git a/lib/Makefile b/lib/Makefile
index d3daedf93c5a..907759f28916 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -183,6 +183,7 @@ lib-$(CONFIG_GENERIC_BUG) += bug.o
obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o
obj-$(CONFIG_DYNAMIC_DEBUG) += dynamic_debug.o
+obj-$(CONFIG_SYMBOLIC_ERRNAME) += errname.o
obj-$(CONFIG_NLATTR) += nlattr.o
diff --git a/lib/errname.c b/lib/errname.c
new file mode 100644
index 000000000000..0c4d3e66170e
--- /dev/null
+++ b/lib/errname.c
@@ -0,0 +1,223 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/build_bug.h>
+#include <linux/errno.h>
+#include <linux/errname.h>
+#include <linux/kernel.h>
+
+/*
+ * Ensure these tables do not accidentally become gigantic if some
+ * huge errno makes it in. On most architectures, the first table will
+ * only have about 140 entries, but mips and parisc have more sparsely
+ * allocated errnos (with EHWPOISON = 257 on parisc, and EDQUOT = 1133
+ * on mips), so this wastes a bit of space on those - though we
+ * special case the EDQUOT case.
+ */
+#define E(err) [err + BUILD_BUG_ON_ZERO(err <= 0 || err > 300)] = "-" #err
+static const char *names_0[] = {
+ E(E2BIG),
+ E(EACCES),
+ E(EADDRINUSE),
+ E(EADDRNOTAVAIL),
+ E(EADV),
+ E(EAFNOSUPPORT),
+ E(EALREADY),
+ E(EBADE),
+ E(EBADF),
+ E(EBADFD),
+ E(EBADMSG),
+ E(EBADR),
+ E(EBADRQC),
+ E(EBADSLT),
+ E(EBFONT),
+ E(EBUSY),
+#ifdef ECANCELLED
+ E(ECANCELLED),
+#endif
+ E(ECHILD),
+ E(ECHRNG),
+ E(ECOMM),
+ E(ECONNABORTED),
+ E(ECONNRESET),
+ E(EDEADLOCK),
+ E(EDESTADDRREQ),
+ E(EDOM),
+ E(EDOTDOT),
+#ifndef CONFIG_MIPS
+ E(EDQUOT),
+#endif
+ E(EEXIST),
+ E(EFAULT),
+ E(EFBIG),
+ E(EHOSTDOWN),
+ E(EHOSTUNREACH),
+ E(EHWPOISON),
+ E(EIDRM),
+ E(EILSEQ),
+#ifdef EINIT
+ E(EINIT),
+#endif
+ E(EINPROGRESS),
+ E(EINTR),
+ E(EINVAL),
+ E(EIO),
+ E(EISCONN),
+ E(EISDIR),
+ E(EISNAM),
+ E(EKEYEXPIRED),
+ E(EKEYREJECTED),
+ E(EKEYREVOKED),
+ E(EL2HLT),
+ E(EL2NSYNC),
+ E(EL3HLT),
+ E(EL3RST),
+ E(ELIBACC),
+ E(ELIBBAD),
+ E(ELIBEXEC),
+ E(ELIBMAX),
+ E(ELIBSCN),
+ E(ELNRNG),
+ E(ELOOP),
+ E(EMEDIUMTYPE),
+ E(EMFILE),
+ E(EMLINK),
+ E(EMSGSIZE),
+ E(EMULTIHOP),
+ E(ENAMETOOLONG),
+ E(ENAVAIL),
+ E(ENETDOWN),
+ E(ENETRESET),
+ E(ENETUNREACH),
+ E(ENFILE),
+ E(ENOANO),
+ E(ENOBUFS),
+ E(ENOCSI),
+ E(ENODATA),
+ E(ENODEV),
+ E(ENOENT),
+ E(ENOEXEC),
+ E(ENOKEY),
+ E(ENOLCK),
+ E(ENOLINK),
+ E(ENOMEDIUM),
+ E(ENOMEM),
+ E(ENOMSG),
+ E(ENONET),
+ E(ENOPKG),
+ E(ENOPROTOOPT),
+ E(ENOSPC),
+ E(ENOSR),
+ E(ENOSTR),
+#ifdef ENOSYM
+ E(ENOSYM),
+#endif
+ E(ENOSYS),
+ E(ENOTBLK),
+ E(ENOTCONN),
+ E(ENOTDIR),
+ E(ENOTEMPTY),
+ E(ENOTNAM),
+ E(ENOTRECOVERABLE),
+ E(ENOTSOCK),
+ E(ENOTTY),
+ E(ENOTUNIQ),
+ E(ENXIO),
+ E(EOPNOTSUPP),
+ E(EOVERFLOW),
+ E(EOWNERDEAD),
+ E(EPERM),
+ E(EPFNOSUPPORT),
+ E(EPIPE),
+#ifdef EPROCLIM
+ E(EPROCLIM),
+#endif
+ E(EPROTO),
+ E(EPROTONOSUPPORT),
+ E(EPROTOTYPE),
+ E(ERANGE),
+ E(EREMCHG),
+#ifdef EREMDEV
+ E(EREMDEV),
+#endif
+ E(EREMOTE),
+ E(EREMOTEIO),
+#ifdef EREMOTERELEASE
+ E(EREMOTERELEASE),
+#endif
+ E(ERESTART),
+ E(ERFKILL),
+ E(EROFS),
+#ifdef ERREMOTE
+ E(ERREMOTE),
+#endif
+ E(ESHUTDOWN),
+ E(ESOCKTNOSUPPORT),
+ E(ESPIPE),
+ E(ESRCH),
+ E(ESRMNT),
+ E(ESTALE),
+ E(ESTRPIPE),
+ E(ETIME),
+ E(ETIMEDOUT),
+ E(ETOOMANYREFS),
+ E(ETXTBSY),
+ E(EUCLEAN),
+ E(EUNATCH),
+ E(EUSERS),
+ E(EXDEV),
+ E(EXFULL),
+
+ E(ECANCELED), /* ECANCELLED */
+ E(EAGAIN), /* EWOULDBLOCK */
+ E(ECONNREFUSED), /* EREFUSED */
+ E(EDEADLK), /* EDEADLOCK */
+};
+#undef E
+
+#define E(err) [err - 512 + BUILD_BUG_ON_ZERO(err < 512 || err > 550)] = "-" #err
+static const char *names_512[] = {
+ E(ERESTARTSYS),
+ E(ERESTARTNOINTR),
+ E(ERESTARTNOHAND),
+ E(ENOIOCTLCMD),
+ E(ERESTART_RESTARTBLOCK),
+ E(EPROBE_DEFER),
+ E(EOPENSTALE),
+ E(ENOPARAM),
+
+ E(EBADHANDLE),
+ E(ENOTSYNC),
+ E(EBADCOOKIE),
+ E(ENOTSUPP),
+ E(ETOOSMALL),
+ E(ESERVERFAULT),
+ E(EBADTYPE),
+ E(EJUKEBOX),
+ E(EIOCBQUEUED),
+ E(ERECALLCONFLICT),
+};
+#undef E
+
+static const char *__errname(unsigned err)
+{
+ if (err < ARRAY_SIZE(names_0))
+ return names_0[err];
+ if (err >= 512 && err - 512 < ARRAY_SIZE(names_512))
+ return names_512[err - 512];
+ /* But why? */
+ if (IS_ENABLED(CONFIG_MIPS) && err == EDQUOT) /* 1133 */
+ return "-EDQUOT";
+ return NULL;
+}
+
+/*
+ * errname(EIO) -> "EIO"
+ * errname(-EIO) -> "-EIO"
+ */
+const char *errname(int err)
+{
+ const char *name = __errname(abs(err));
+ if (!name)
+ return NULL;
+
+ return err > 0 ? name + 1 : name;
+}
diff --git a/lib/test_printf.c b/lib/test_printf.c
index 5d94cbff2120..030daeb4fe21 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -593,6 +593,26 @@ flags(void)
kfree(cmp_buffer);
}
+static void __init
+errptr(void)
+{
+ test("-1234", "%pe", ERR_PTR(-1234));
+
+ /* Check that %pe with a non-ERR_PTR gets treated as ordinary %p. */
+ BUILD_BUG_ON(IS_ERR(PTR));
+ test_hashed("%pe", PTR);
+
+#ifdef CONFIG_SYMBOLIC_ERRNAME
+ test("(-ENOTSOCK)", "(%pe)", ERR_PTR(-ENOTSOCK));
+ test("(-EAGAIN)", "(%pe)", ERR_PTR(-EAGAIN));
+ BUILD_BUG_ON(EAGAIN != EWOULDBLOCK);
+ test("(-EAGAIN)", "(%pe)", ERR_PTR(-EWOULDBLOCK));
+ test("[-EIO ]", "[%-8pe]", ERR_PTR(-EIO));
+ test("[ -EIO]", "[%8pe]", ERR_PTR(-EIO));
+ test("-EPROBE_DEFER", "%pe", ERR_PTR(-EPROBE_DEFER));
+#endif
+}
+
static void __init
test_pointer(void)
{
@@ -615,6 +635,7 @@ test_pointer(void)
bitmap();
netdev_features();
flags();
+ errptr();
}
static void __init selftest(void)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index e78017a3e1bd..b54d252b398e 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -21,6 +21,7 @@
#include <linux/build_bug.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
+#include <linux/errname.h>
#include <linux/module.h> /* for KSYM_SYMBOL_LEN */
#include <linux/types.h>
#include <linux/string.h>
@@ -613,6 +614,25 @@ static char *string_nocheck(char *buf, char *end, const char *s,
return widen_string(buf, len, end, spec);
}
+static char *err_ptr(char *buf, char *end, void *ptr,
+ struct printf_spec spec)
+{
+ int err = PTR_ERR(ptr);
+ const char *sym = errname(err);
+
+ if (sym)
+ return string_nocheck(buf, end, sym, spec);
+
+ /*
+ * Somebody passed ERR_PTR(-1234) or some other non-existing
+ * Efoo - or perhaps CONFIG_SYMBOLIC_ERRNAME=n. Fall back to
+ * printing it as its decimal representation.
+ */
+ spec.flags |= SIGN;
+ spec.base = 10;
+ return number(buf, end, err, spec);
+}
+
/* Be careful: error messages must fit into the given buffer. */
static char *error_string(char *buf, char *end, const char *s,
struct printf_spec spec)
@@ -2187,6 +2207,11 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
return kobject_string(buf, end, ptr, spec, fmt);
case 'x':
return pointer_string(buf, end, ptr, spec);
+ case 'e':
+ /* %pe with a non-ERR_PTR gets treated as plain %p */
+ if (!IS_ERR(ptr))
+ break;
+ return err_ptr(buf, end, ptr, spec);
}
/* default is to _not_ leak addresses, hash before printing */
@@ -2823,6 +2848,7 @@ int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args)
case 'f':
case 'x':
case 'K':
+ case 'e':
save_arg(void *);
break;
default:
@@ -2999,6 +3025,7 @@ int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf)
case 'f':
case 'x':
case 'K':
+ case 'e':
process = true;
break;
default: