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Date: Thu, 27 Sep 2018 22:59:18 +0000
From: Paul Burton <paul.burton@...s.com>
To: "linux-mips@...ux-mips.org" <linux-mips@...ux-mips.org>,
Rob Herring <robh+dt@...nel.org>
CC: Paul Burton <pburton@...ecomp.com>,
Frank Rowand <frowand.list@...il.com>,
Jaedon Shin <jaedon.shin@...il.com>,
Mathieu Malaterre <malat@...ian.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: [PATCH v2] MIPS: Fix CONFIG_CMDLINE handling
Commit 8ce355cf2e38 ("MIPS: Setup boot_command_line before
plat_mem_setup") fixed a problem for systems which have
CONFIG_CMDLINE_BOOL=y & use a DT with a chosen node that has either no
bootargs property or an empty one. In this configuration
early_init_dt_scan_chosen() copies CONFIG_CMDLINE into
boot_command_line, but the MIPS code doesn't know this so it appends
CONFIG_CMDLINE (via builtin_cmdline) to boot_command_line again. The
result is that boot_command_line contains the arguments from
CONFIG_CMDLINE twice.
That commit took the approach of simply setting up boot_command_line
from the MIPS code before early_init_dt_scan_chosen() runs, causing it
not to copy CONFIG_CMDLINE to boot_command_line if a chosen node with no
bootargs property is found.
Unfortunately this is problematic for systems which do have a non-empty
bootargs property & CONFIG_CMDLINE_BOOL=y. There
early_init_dt_scan_chosen() will overwrite boot_command_line with the
arguments from DT, which means we lose those from CONFIG_CMDLINE
entirely. This breaks CONFIG_MIPS_CMDLINE_DTB_EXTEND. If we have
CONFIG_MIPS_CMDLINE_FROM_BOOTLOADER or
CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND selected and the DT has a bootargs
property which we should ignore, it will instead be honoured breaking
those configurations too.
Fix this by reverting commit 8ce355cf2e38 ("MIPS: Setup
boot_command_line before plat_mem_setup") to restore the former
behaviour, and fixing the CONFIG_CMDLINE duplication issue by
initializing boot_command_line to a non-empty string that
early_init_dt_scan_chosen() will not overwrite with CONFIG_CMDLINE.
This is a little ugly, but cleanup in this area is on its way. In the
meantime this is at least easy to backport & contains the ugliness
within arch/mips/.
Signed-off-by: Paul Burton <paul.burton@...s.com>
Fixes: 8ce355cf2e38 ("MIPS: Setup boot_command_line before plat_mem_setup")
References: https://patchwork.linux-mips.org/patch/18804/
Cc: Frank Rowand <frowand.list@...il.com>
Cc: Jaedon Shin <jaedon.shin@...il.com>
Cc: Mathieu Malaterre <malat@...ian.org>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: devicetree@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Cc: linux-mips@...ux-mips.org
Cc: stable@...r.kernel.org # v4.16+
---
This isn't pretty, but further cleanup is underway [1] and this fixes
the regression in an easily backportable manner without adding another
per-architecture function like v1.
[1] https://www.spinics.net/lists/kernel/msg2918275.html
Changes in v2:
- Drop the arch-specific function & just initialize boot_command_line
such that early_init_dt_scan_chosen() won't overwrite it with
CONFIG_CMDLINE.
v1: https://marc.info/?l=linux-mips&m=153634652318477&w=2
https://marc.info/?l=linux-mips&m=153634653718485&w=2
---
arch/mips/kernel/setup.c | 48 +++++++++++++++++++++++-----------------
1 file changed, 28 insertions(+), 20 deletions(-)
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index c71d1eb7da59..8aaaa42f91ed 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -846,6 +846,34 @@ static void __init arch_mem_init(char **cmdline_p)
struct memblock_region *reg;
extern void plat_mem_setup(void);
+ /*
+ * Initialize boot_command_line to an innocuous but non-empty string in
+ * order to prevent early_init_dt_scan_chosen() from copying
+ * CONFIG_CMDLINE into it without our knowledge. We handle
+ * CONFIG_CMDLINE ourselves below & don't want to duplicate its
+ * content because repeating arguments can be problematic.
+ */
+ strlcpy(boot_command_line, " ", COMMAND_LINE_SIZE);
+
+ /* call board setup routine */
+ plat_mem_setup();
+
+ /*
+ * Make sure all kernel memory is in the maps. The "UP" and
+ * "DOWN" are opposite for initdata since if it crosses over
+ * into another memory section you don't want that to be
+ * freed when the initdata is freed.
+ */
+ arch_mem_addpart(PFN_DOWN(__pa_symbol(&_text)) << PAGE_SHIFT,
+ PFN_UP(__pa_symbol(&_edata)) << PAGE_SHIFT,
+ BOOT_MEM_RAM);
+ arch_mem_addpart(PFN_UP(__pa_symbol(&__init_begin)) << PAGE_SHIFT,
+ PFN_DOWN(__pa_symbol(&__init_end)) << PAGE_SHIFT,
+ BOOT_MEM_INIT_RAM);
+
+ pr_info("Determined physical RAM map:\n");
+ print_memory_map();
+
#if defined(CONFIG_CMDLINE_BOOL) && defined(CONFIG_CMDLINE_OVERRIDE)
strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
#else
@@ -873,26 +901,6 @@ static void __init arch_mem_init(char **cmdline_p)
}
#endif
#endif
-
- /* call board setup routine */
- plat_mem_setup();
-
- /*
- * Make sure all kernel memory is in the maps. The "UP" and
- * "DOWN" are opposite for initdata since if it crosses over
- * into another memory section you don't want that to be
- * freed when the initdata is freed.
- */
- arch_mem_addpart(PFN_DOWN(__pa_symbol(&_text)) << PAGE_SHIFT,
- PFN_UP(__pa_symbol(&_edata)) << PAGE_SHIFT,
- BOOT_MEM_RAM);
- arch_mem_addpart(PFN_UP(__pa_symbol(&__init_begin)) << PAGE_SHIFT,
- PFN_DOWN(__pa_symbol(&__init_end)) << PAGE_SHIFT,
- BOOT_MEM_INIT_RAM);
-
- pr_info("Determined physical RAM map:\n");
- print_memory_map();
-
strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
*cmdline_p = command_line;
--
2.19.0
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