Re: [PATCH v2 4/7] CMDLINE: powerpc: convert to generic builtin command line
From: Christophe Leroy <hidden>
Date: 2021-03-13 09:30:37
Also in:
linux-mips, lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
Le 09/03/2021 à 22:40, Daniel Walker a écrit :
On Tue, Mar 09, 2021 at 08:56:47AM +0100, Christophe Leroy wrote:quoted
So we are referencing a function that doesn't exist (namely prom_strlcat). But it works because cmdline_add_builtin_custom() looks like a function but is in fact an obscure macro that doesn't use prom_strlcat() unless GENERIC_CMDLINE_NEED_STRLCAT is defined. IMHO that's awful for readability and code maintenance.powerpc is a special case, there's no other users like this. The reason is because of all the difficulty in this prom_init.c code. A lot of the generic code has similar kind of changes to work across architectures.
I'd suggest the following (sorry if Thunderbird damages whitespaces, you'll get the idea anyway)
diff --git a/include/linux/cmdline.h b/include/linux/cmdline.h
new file mode 100644
index 000000000000..30b9eefc802f
--- /dev/null
+++ b/include/linux/cmdline.h@@ -0,0 +1,42 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_CMDLINE_H +#define _LINUX_CMDLINE_H + +#ifdef CONFIG_GENERIC_CMDLINE + +#ifndef cmdline_strlcpy +#define cmdline_strlcpy strlcpy +#endif +#ifndef cmdline_strlcat +#define cmdline_strlcat strlcat +#endif + +static __always_inline void +cmdline_add_builtin_custom(char *dest, const char *src, char *tmp, unsigned long length) +{ + if (WARN_ON(sizeof(CONFIG_CMDLINE_PREPEND) > 1 && + !IS_ENABLED(CONFIG_CMDLINE_OVERRIDE) && + !tmp && src == dest)) + return; + + if (sizeof(CONFIG_CMDLINE_PREPEND) > 1 && + !IS_ENABLED(CONFIG_CMDLINE_OVERRIDE) && src == dest) + cmdline_strlcpy(tmp, src, length); + else + tmp = (char *)src; + + cmdline_strlcpy(dest, CONFIG_CMDLINE_PREPEND " ", length); + if (!IS_ENABLED(CONFIG_CMDLINE_OVERRIDE) && tmp) + cmdline_strlcat(dest, tmp, length); + cmdline_strlcat(dest, " " CONFIG_CMDLINE_APPEND, length); +} + +#define cmdline_add_builtin(dest, src, length) do { \ + static __init char cmdline_tmp[length]; \ + \ + cmdline_add_builtin_custom(dest, src, cmdline_tmp, length); \ +} while (0) + +#endif /* CONFIG_GENERIC_CMDLINE */ + +#endif /* _LINUX_CMDLINE_H */
diff --git a/init/Kconfig b/init/Kconfig
index 22946fe5ded9..aeb134f0703b 100644
--- a/init/Kconfig
+++ b/init/Kconfig@@ -2035,6 +2035,27 @@ config PROFILING config TRACEPOINTS bool +config GENERIC_CMDLINE + bool + +if GENERIC_CMDLINE + +config CMDLINE_BOOL + bool "Built-in kernel command line" + +config CMDLINE_APPEND + string "Built-in kernel command string append" if CMDLINE_BOOL + default "" + +config CMDLINE_PREPEND + string "Built-in kernel command string prepend" if CMDLINE_BOOL + default "" + +config CMDLINE_OVERRIDE + bool "Built-in command line overrides boot loader arguments" if CMDLINE_BOOL + +endif + endmenu # General setup source "arch/Kconfig"
--
Then on powerpc you do:
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index 2c2f33155317..1649787c3953 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -152,7 +152,7 @@ static struct prom_t __prombss prom;
static unsigned long __prombss prom_entry;
static char __prombss of_stdout_device[256];
-static char __prombss prom_scratch[256];
+static char __prombss prom_scratch[COMMAND_LINE_SIZE];
static unsigned long __prombss dt_header_start;
static unsigned long __prombss dt_struct_start, dt_struct_end;
@@ -770,6 +770,12 @@ static unsigned long prom_memparse(const char *ptr, const char **retptr)
* Early parsing of the command line passed to the kernel, used for
* "mem=x" and the options that affect the iommu
*/
+
+#define cmdline_strlcpy prom_strlcpy
+#define cmdline_strlcat prom_strlcat
+
+#include <linux/cmdline.h>
+
static void __init early_cmdline_parse(void)
{
const char *opt;
@@ -780,12 +786,11 @@ static void __init early_cmdline_parse(void)
prom_cmd_line[0] = 0;
p = prom_cmd_line;
- if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && (long)prom.chosen > 0)
+ if ((long)prom.chosen > 0)
l = prom_getprop(prom.chosen, "bootargs", p, COMMAND_LINE_SIZE-1);
- if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || l <= 0 || p[0] == '\0')
- prom_strlcat(prom_cmd_line, " " CONFIG_CMDLINE,
- sizeof(prom_cmd_line));
+ cmdline_add_builtin_custom(prom_cmd_line, (l > 0 ? p : NULL),
+ prom_scratch, sizeof(prom_cmd_line));
prom_printf("command line: %s\n", prom_cmd_line);
--
2.25.0
Christophe