On 3/5/24 00:28, Conor Dooley wrote:
From: Conor Dooley <conor.doo...@microchip.com>The first multi-letter extension after the single-letter extensions does not have to be preceded by an underscore, which could cause the parser to mistakenly find a single-letter extension after the start of the multi-letter portion of the string. Three letters precede multi-letter extensions (s, x & z), none of which are valid single-letter extensions. The dt-binding also allows multi-letter extensions starting with h, but no such extension have been frozen or ratified, and the unprivileged spec no longer uses "h" as a prefix for multi-letter hypervisor extensions, having moved to "sh" instead. For that reason, modify the parser to stop at s, x & z to prevent this overrun, ignoring h. Signed-off-by: Conor Dooley <conor.doo...@microchip.com> --- The parser in U-Boot only supports single-letter extensions & the single-letter h has to be at the end of the single-letter section, so it would not be difficult to terminate parsing once a h is seen (you'd need to support the hypervisor extension to support additional hypervisor extensions after all) if in the future a multi-letter extension starting with h did come about. I've got no problem adding a special case for h, but I'm tempted to just remove the multi-letter h extensions from the binding, given there's actually not going to be any extensions ratified using that naming scheme. CC: Rick Chen <r...@andestech.com> CC: Leo <ycli...@andestech.com> CC: Tom Rini <tr...@konsulko.com> CC: Simon Glass <s...@chromium.org> CC: Chanho Park <chanho61.p...@samsung.com> CC: Heinrich Schuchardt <xypron.g...@gmx.de> CC: Bin Meng <bmeng...@gmail.com> CC: Conor Dooley <conor.doo...@microchip.com> CC: pal...@dabbelt.com CC: u-boot@lists.denx.de --- arch/riscv/cpu/cpu.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/arch/riscv/cpu/cpu.c b/arch/riscv/cpu/cpu.c index 8445c5823e..ecfefa1a02 100644 --- a/arch/riscv/cpu/cpu.c +++ b/arch/riscv/cpu/cpu.c @@ -49,14 +49,24 @@ static inline bool supports_extension(char ext) } if (!cpu_get_desc(dev, desc, sizeof(desc))) { /* - * skip the first 4 characters (rv32|rv64) and - * check until underscore + * skip the first 4 characters (rv32|rv64) */ for (i = 4; i < sizeof(desc); i++) { - if (desc[i] == '_' || desc[i] == '\0') - break; - if (desc[i] == ext) - return true; + switch (desc[i]) { + case 's': + case 'x': + case 'z': + case '_': + case '\0': + /* + * Any of these characters mean the single + * letter extensions have all been consumed. + */ + return false; + default: + if (desc[i] == ext) + return true; + } } }
According to https://github.com/riscv/riscv-isa-manual/blob/main/src/naming.adoc the ISA string is case insensitive. Why can we assume here that it is lower case? Best regards Heinrich
