| Message ID | 20210225125921.13147-2-will@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Fix CMDLINE_EXTEND handling for FDT "bootargs" | expand |
On Thu, 25 Feb 2021 12:59:20 +0000, Will Deacon <will@kernel.org> wrote: > > The built-in kernel commandline (CONFIG_CMDLINE) can be configured in > three different ways: > > 1. CMDLINE_FORCE: Use CONFIG_CMDLINE instead of any bootloader args > 2. CMDLINE_EXTEND: Append the bootloader args to CONFIG_CMDLINE > 3. CMDLINE_FROM_BOOTLOADER: Only use CONFIG_CMDLINE if there aren't > any bootloader args. > > The early cmdline parsing to detect idreg overrides gets (2) and (3) > slightly wrong: in the case of (2) the bootloader args are parsed first > and in the case of (3) the CMDLINE is always parsed. > > Fix these issues by moving the bootargs parsing out into a helper > function and following the same logic as that used by the EFI stub. > > Cc: Marc Zyngier <maz@kernel.org> > Fixes: 33200303553d ("arm64: cpufeature: Add an early command-line cpufeature override facility") > Signed-off-by: Will Deacon <will@kernel.org> > --- > arch/arm64/kernel/idreg-override.c | 44 +++++++++++++++++------------- > 1 file changed, 25 insertions(+), 19 deletions(-) > > diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c > index dffb16682330..cc071712c6f9 100644 > --- a/arch/arm64/kernel/idreg-override.c > +++ b/arch/arm64/kernel/idreg-override.c > @@ -163,33 +163,39 @@ static __init void __parse_cmdline(const char *cmdline, bool parse_aliases) > } while (1); > } > > -static __init void parse_cmdline(void) > +static __init const u8 *get_bootargs_cmdline(void) > { > - if (!IS_ENABLED(CONFIG_CMDLINE_FORCE)) { > - const u8 *prop; > - void *fdt; > - int node; > + const u8 *prop; > + void *fdt; > + int node; > > - fdt = get_early_fdt_ptr(); > - if (!fdt) > - goto out; > + fdt = get_early_fdt_ptr(); > + if (!fdt) > + return NULL; > > - node = fdt_path_offset(fdt, "/chosen"); > - if (node < 0) > - goto out; > + node = fdt_path_offset(fdt, "/chosen"); > + if (node < 0) > + return NULL; > > - prop = fdt_getprop(fdt, node, "bootargs", NULL); > - if (!prop) > - goto out; > + prop = fdt_getprop(fdt, node, "bootargs", NULL); > + if (!prop) > + return NULL; > > - __parse_cmdline(prop, true); > + return strlen(prop) ? prop : NULL; > +} > > - if (!IS_ENABLED(CONFIG_CMDLINE_EXTEND)) > - return; > +static __init void parse_cmdline(void) > +{ > + const u8 *prop = get_bootargs_cmdline(); > + > + if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || > + IS_ENABLED(CONFIG_CMDLINE_FORCE) || > + !prop) { The logic hurts, but I think I grok it now. The last term is actually a reduction of (IS_ENABLED(CONFIG_CMDLINE_FROM_BOOTLOADER) && !prop) and we know for sure that if none of the other two terms are true, then CMDLINE_FROM_BOOTLOADER *must* be enabled. > + __parse_cmdline(CONFIG_CMDLINE, true); > } > > -out: > - __parse_cmdline(CONFIG_CMDLINE, true); > + if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && prop) > + __parse_cmdline(prop, true); > } > > /* Keep checkers quiet */ I don't think we need to backport anything to stable for the nokaslr handling, do we? Otherwise, Reviewed-by: Marc Zyngier <maz@kernel.org> Thanks, M.
On Thu, Feb 25, 2021 at 01:53:56PM +0000, Marc Zyngier wrote: > On Thu, 25 Feb 2021 12:59:20 +0000, > Will Deacon <will@kernel.org> wrote: > > > > The built-in kernel commandline (CONFIG_CMDLINE) can be configured in > > three different ways: > > > > 1. CMDLINE_FORCE: Use CONFIG_CMDLINE instead of any bootloader args > > 2. CMDLINE_EXTEND: Append the bootloader args to CONFIG_CMDLINE > > 3. CMDLINE_FROM_BOOTLOADER: Only use CONFIG_CMDLINE if there aren't > > any bootloader args. > > > > The early cmdline parsing to detect idreg overrides gets (2) and (3) > > slightly wrong: in the case of (2) the bootloader args are parsed first > > and in the case of (3) the CMDLINE is always parsed. > > > > Fix these issues by moving the bootargs parsing out into a helper > > function and following the same logic as that used by the EFI stub. > > > > Cc: Marc Zyngier <maz@kernel.org> > > Fixes: 33200303553d ("arm64: cpufeature: Add an early command-line cpufeature override facility") > > Signed-off-by: Will Deacon <will@kernel.org> > > --- > > arch/arm64/kernel/idreg-override.c | 44 +++++++++++++++++------------- > > 1 file changed, 25 insertions(+), 19 deletions(-) > > > > diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c > > index dffb16682330..cc071712c6f9 100644 > > --- a/arch/arm64/kernel/idreg-override.c > > +++ b/arch/arm64/kernel/idreg-override.c > > @@ -163,33 +163,39 @@ static __init void __parse_cmdline(const char *cmdline, bool parse_aliases) > > } while (1); > > } > > > > -static __init void parse_cmdline(void) > > +static __init const u8 *get_bootargs_cmdline(void) > > { > > - if (!IS_ENABLED(CONFIG_CMDLINE_FORCE)) { > > - const u8 *prop; > > - void *fdt; > > - int node; > > + const u8 *prop; > > + void *fdt; > > + int node; > > > > - fdt = get_early_fdt_ptr(); > > - if (!fdt) > > - goto out; > > + fdt = get_early_fdt_ptr(); > > + if (!fdt) > > + return NULL; > > > > - node = fdt_path_offset(fdt, "/chosen"); > > - if (node < 0) > > - goto out; > > + node = fdt_path_offset(fdt, "/chosen"); > > + if (node < 0) > > + return NULL; > > > > - prop = fdt_getprop(fdt, node, "bootargs", NULL); > > - if (!prop) > > - goto out; > > + prop = fdt_getprop(fdt, node, "bootargs", NULL); > > + if (!prop) > > + return NULL; > > > > - __parse_cmdline(prop, true); > > + return strlen(prop) ? prop : NULL; > > +} > > > > - if (!IS_ENABLED(CONFIG_CMDLINE_EXTEND)) > > - return; > > +static __init void parse_cmdline(void) > > +{ > > + const u8 *prop = get_bootargs_cmdline(); > > + > > + if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || > > + IS_ENABLED(CONFIG_CMDLINE_FORCE) || > > + !prop) { > > The logic hurts, but I think I grok it now. The last term is actually > a reduction of > > (IS_ENABLED(CONFIG_CMDLINE_FROM_BOOTLOADER) && !prop) > > and we know for sure that if none of the other two terms are true, > then CMDLINE_FROM_BOOTLOADER *must* be enabled. Yes, with one gotcha: when CONFIG_CMDLINE is "", I don't think any of the CONFIG_CMDLINE_* are set, but the behaviour ends up being the same as CMDLINE_FROM_BOOTLOADER. > > > + __parse_cmdline(CONFIG_CMDLINE, true); > > } > > > > -out: > > - __parse_cmdline(CONFIG_CMDLINE, true); > > + if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && prop) > > + __parse_cmdline(prop, true); > > } > > > > /* Keep checkers quiet */ > > I don't think we need to backport anything to stable for the nokaslr > handling, do we? No, I don't think so. There isn't a "kaslr" or "nonokaslr", so the ordering doesn't matter afaict. > Reviewed-by: Marc Zyngier <maz@kernel.org> Cheers! Will
diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c index dffb16682330..cc071712c6f9 100644 --- a/arch/arm64/kernel/idreg-override.c +++ b/arch/arm64/kernel/idreg-override.c @@ -163,33 +163,39 @@ static __init void __parse_cmdline(const char *cmdline, bool parse_aliases) } while (1); } -static __init void parse_cmdline(void) +static __init const u8 *get_bootargs_cmdline(void) { - if (!IS_ENABLED(CONFIG_CMDLINE_FORCE)) { - const u8 *prop; - void *fdt; - int node; + const u8 *prop; + void *fdt; + int node; - fdt = get_early_fdt_ptr(); - if (!fdt) - goto out; + fdt = get_early_fdt_ptr(); + if (!fdt) + return NULL; - node = fdt_path_offset(fdt, "/chosen"); - if (node < 0) - goto out; + node = fdt_path_offset(fdt, "/chosen"); + if (node < 0) + return NULL; - prop = fdt_getprop(fdt, node, "bootargs", NULL); - if (!prop) - goto out; + prop = fdt_getprop(fdt, node, "bootargs", NULL); + if (!prop) + return NULL; - __parse_cmdline(prop, true); + return strlen(prop) ? prop : NULL; +} - if (!IS_ENABLED(CONFIG_CMDLINE_EXTEND)) - return; +static __init void parse_cmdline(void) +{ + const u8 *prop = get_bootargs_cmdline(); + + if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || + IS_ENABLED(CONFIG_CMDLINE_FORCE) || + !prop) { + __parse_cmdline(CONFIG_CMDLINE, true); } -out: - __parse_cmdline(CONFIG_CMDLINE, true); + if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && prop) + __parse_cmdline(prop, true); } /* Keep checkers quiet */
The built-in kernel commandline (CONFIG_CMDLINE) can be configured in three different ways: 1. CMDLINE_FORCE: Use CONFIG_CMDLINE instead of any bootloader args 2. CMDLINE_EXTEND: Append the bootloader args to CONFIG_CMDLINE 3. CMDLINE_FROM_BOOTLOADER: Only use CONFIG_CMDLINE if there aren't any bootloader args. The early cmdline parsing to detect idreg overrides gets (2) and (3) slightly wrong: in the case of (2) the bootloader args are parsed first and in the case of (3) the CMDLINE is always parsed. Fix these issues by moving the bootargs parsing out into a helper function and following the same logic as that used by the EFI stub. Cc: Marc Zyngier <maz@kernel.org> Fixes: 33200303553d ("arm64: cpufeature: Add an early command-line cpufeature override facility") Signed-off-by: Will Deacon <will@kernel.org> --- arch/arm64/kernel/idreg-override.c | 44 +++++++++++++++++------------- 1 file changed, 25 insertions(+), 19 deletions(-)