From 57f5677e535ba24b8926a7125be2ef8d7f09323c Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Tue, 15 Oct 2019 21:07:05 +0200 Subject: printf: add support for printing symbolic error names MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It has been suggested several times to extend vsnprintf() to be able to convert the numeric value of ENOSPC to print "ENOSPC". This implements that as a %p extension: With %pe, one can do if (IS_ERR(foo)) { pr_err("Sorry, can't do that: %pe\n", foo); return PTR_ERR(foo); } instead of what is seen in quite a few places in the kernel: if (IS_ERR(foo)) { pr_err("Sorry, can't do that: %ld\n", PTR_ERR(foo)); return PTR_ERR(foo); } If the value passed to %pe is an ERR_PTR, but the library function errname() added here doesn't know about the value, the value is simply printed in decimal. If the value passed to %pe is not an ERR_PTR, we treat it as an ordinary %p and thus print the hashed value (passing non-ERR_PTR values to %pe indicates a bug in the caller, but we can't do much about that). With my embedded hat on, and because it's not very invasive to do, I've made it possible to remove this. The errname() function and associated lookup tables take up about 3K. For most, that's probably quite acceptable and a price worth paying for more readable dmesg (once this starts getting used), while for those that disable printk() it's of very little use - I don't see a procfs/sysfs/seq_printf() file reasonably making use of this - and they clearly want to squeeze vmlinux as much as possible. Hence the default y if PRINTK. The symbols to include have been found by massaging the output of find arch include -iname 'errno*.h' | xargs grep -E 'define\s*E' In the cases where some common aliasing exists (e.g. EAGAIN=EWOULDBLOCK on all platforms, EDEADLOCK=EDEADLK on most), I've moved the more popular one (in terms of 'git grep -w Efoo | wc) to the bottom so that one takes precedence. Link: http://lkml.kernel.org/r/20191015190706.15989-1-linux@rasmusvillemoes.dk To: "Jonathan Corbet" To: linux-kernel@vger.kernel.org Cc: "Andy Shevchenko" Cc: "Andrew Morton" Cc: "Joe Perches" Cc: linux-doc@vger.kernel.org Signed-off-by: Rasmus Villemoes Acked-by: Uwe Kleine-König Reviewed-by: Petr Mladek [andy.shevchenko@gmail.com: use abs()] Acked-by: Andy Shevchenko Signed-off-by: Petr Mladek --- lib/Kconfig.debug | 9 +++ lib/Makefile | 1 + lib/errname.c | 223 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ lib/test_printf.c | 21 +++++ lib/vsprintf.c | 27 +++++++ 5 files changed, 281 insertions(+) create mode 100644 lib/errname.c (limited to 'lib') 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 +#include +#include +#include + +/* + * 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 #include #include +#include #include /* for KSYM_SYMBOL_LEN */ #include #include @@ -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: -- cgit v1.2.3-59-g8ed1b