Re: [PATCH v2 4/7] CMDLINE: powerpc: convert to generic builtin command line
From: Christophe Leroy
Date: Wed Mar 24 2021 - 11:33:08 EST
Le 09/03/2021 à 22:40, Daniel Walker a écrit :
On Tue, Mar 09, 2021 at 08:56:47AM +0100, Christophe Leroy wrote:
Le 09/03/2021 à 01:02, Daniel Walker a écrit :
This updates the powerpc code to use the CONFIG_GENERIC_CMDLINE
option.
Cc: xe-linux-external@xxxxxxxxx
Signed-off-by: Ruslan Ruslichenko <rruslich@xxxxxxxxx>
Signed-off-by: Ruslan Bilovol <rbilovol@xxxxxxxxx>
Signed-off-by: Daniel Walker <danielwa@xxxxxxxxx>
---
arch/powerpc/Kconfig | 37 +--------------------------------
arch/powerpc/kernel/prom.c | 1 +
arch/powerpc/kernel/prom_init.c | 35 ++++++++++++++++++-------------
3 files changed, 23 insertions(+), 50 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 107bb4319e0e..276b06d5c961 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -167,6 +167,7 @@ config PPC
select EDAC_SUPPORT
select GENERIC_ATOMIC64 if PPC32
select GENERIC_CLOCKEVENTS_BROADCAST if SMP
+ select GENERIC_CMDLINE
select GENERIC_CMOS_UPDATE
select GENERIC_CPU_AUTOPROBE
select GENERIC_CPU_VULNERABILITIES if PPC_BARRIER_NOSPEC
@@ -906,42 +907,6 @@ config PPC_DENORMALISATION
Add support for handling denormalisation of single precision
values. Useful for bare metal only. If unsure say Y here.
-config CMDLINE
- string "Initial kernel command string"
- default ""
- help
- On some platforms, there is currently no way for the boot loader to
- pass arguments to the kernel. For these platforms, you can supply
- some command-line options at build time by entering them here. In
- most cases you will need to specify the root device here.
-
-choice
- prompt "Kernel command line type" if CMDLINE != ""
- default CMDLINE_FROM_BOOTLOADER
-
-config CMDLINE_FROM_BOOTLOADER
- bool "Use bootloader kernel arguments if available"
- help
- Uses the command-line options passed by the boot loader. If
- the boot loader doesn't provide any, the default kernel command
- string provided in CMDLINE will be used.
I can't see how the above is supported in the generic builtin.
Taking into account that it is the default on powerpc, I'm having hardtime with that.
-
-config CMDLINE_EXTEND
- bool "Extend bootloader kernel arguments"
- help
- The command-line arguments provided by the boot loader will be
- appended to the default kernel command string.
-
-config CMDLINE_FORCE
- bool "Always use the default kernel command string"
- help
- Always use the default kernel command string, even if the boot
- loader passes other arguments to the kernel.
- This is useful if you cannot or don't want to change the
- command-line options your boot loader passes to the kernel.
-
-endchoice
-
config EXTRA_TARGETS
string "Additional default image types"
help
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index ae3c41730367..96d0a01be1b4 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -27,6 +27,7 @@
#include <linux/irq.h>
#include <linux/memblock.h>
#include <linux/of.h>
+#include <linux/cmdline.h>
Why is this needed in prom.c ?
Must have been a mistake, I don't think it's needed.
#include <linux/of_fdt.h>
#include <linux/libfdt.h>
#include <linux/cpu.h>
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index e9d4eb6144e1..657241534d69 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -27,6 +27,7 @@
#include <linux/initrd.h>
#include <linux/bitops.h>
#include <linux/pgtable.h>
+#include <linux/cmdline.h>
#include <asm/prom.h>
#include <asm/rtas.h>
#include <asm/page.h>
@@ -242,15 +243,6 @@ static int __init prom_strcmp(const char *cs, const char *ct)
return 0;
}
-static char __init *prom_strcpy(char *dest, const char *src)
-{
- char *tmp = dest;
-
- while ((*dest++ = *src++) != '\0')
- /* nothing */;
- return tmp;
-}
-
This game with prom_strcpy() should go a separate preceeding patch.
Also, it looks like checkpatch.pl recommends to use strscpy() instead of strlcpy().
strscpy() is very large. I'm not sure it's compatible with this prom_init.c
environment.
Ok you are right, lets keep strlcpy() and ignore checkpatch complaints
static int __init prom_strncmp(const char *cs, const char *ct, size_t count)
{
unsigned char c1, c2;
@@ -276,6 +268,20 @@ static size_t __init prom_strlen(const char *s)
return sc - s;
}
+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;
+}
+
+
static int __init prom_memcmp(const void *cs, const void *ct, size_t count)
{
const unsigned char *su1, *su2;
@@ -304,6 +310,7 @@ static char __init *prom_strstr(const char *s1, const char *s2)
return NULL;
}
+#ifdef GENERIC_CMDLINE_NEED_STRLCAT
static size_t __init prom_strlcat(char *dest, const char *src, size_t count)
{
size_t dsize = prom_strlen(dest);
@@ -323,6 +330,7 @@ static size_t __init prom_strlcat(char *dest, const char *src, size_t count)
return res;
}
+#endif
#ifdef CONFIG_PPC_PSERIES
static int __init prom_strtobool(const char *s, bool *res)
@@ -775,12 +783,11 @@ 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), sizeof(prom_cmd_line),
+ __prombss, prom_strlcpy, prom_strlcat);
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.
Any feedback on the proposed changes I made on the 13th ? I know it is partly buggy but that was
more for the principle. I can make clean working patch if it helps.
prom_printf("command line: %s\n", prom_cmd_line);
@@ -2706,7 +2713,7 @@ static void __init flatten_device_tree(void)
/* Add "phandle" in there, we'll need it */
namep = make_room(&mem_start, &mem_end, 16, 1);
- prom_strcpy(namep, "phandle");
+ prom_strlcpy(namep, "phandle", 8);
Should be in a separate patch.
I can move it, I missed that from the first round.
Daniel
Christophe