From 781380d2cdef34559a0125ca6464b90bfc01594f Mon Sep 17 00:00:00 2001 From: =?utf8?q?Miquel=20Sabat=C3=A9=20Sol=C3=A0?= Date: Mon, 15 Sep 2025 16:32:52 +0200 Subject: [PATCH] riscv: kgdb: Ensure that BUFMAX > NUMREGBYTES MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The current value of BUFMAX is similar as in other architectures, but as per documentation on KGDB (see 'Documentation/process/debugging/kgdb.rst'), BUFMAX has to be larger than NUMREGBYTES. Some NUMREGBYTES architectures (e.g. powerpc or hexagon) actually define BUFMAX in relation to NUMREGBYTES, and thus this condition is always guaranteed. Since 2048 is a value that is generally accepted on all architectures, and that is larger than the current value of NUMREGBYTES, we can keep this value in arch/riscv, but we can at least add an 'static_assert' as an extra measure just in case NUMREGBYTES changes in the future for some unforseen reason. Signed-off-by: Miquel Sabaté Solà Link: https://lore.kernel.org/r/20250915143252.154955-1-mikisabate@gmail.com Signed-off-by: Paul Walmsley --- arch/riscv/include/asm/kgdb.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/riscv/include/asm/kgdb.h b/arch/riscv/include/asm/kgdb.h index 7559d728c5ff9..78b18e2fd7717 100644 --- a/arch/riscv/include/asm/kgdb.h +++ b/arch/riscv/include/asm/kgdb.h @@ -3,14 +3,18 @@ #ifndef __ASM_KGDB_H_ #define __ASM_KGDB_H_ +#include + #ifdef __KERNEL__ #define GDB_SIZEOF_REG sizeof(unsigned long) -#define DBG_MAX_REG_NUM (36) -#define NUMREGBYTES ((DBG_MAX_REG_NUM) * GDB_SIZEOF_REG) +#define DBG_MAX_REG_NUM 36 +#define NUMREGBYTES (DBG_MAX_REG_NUM * GDB_SIZEOF_REG) #define CACHE_FLUSH_IS_SAFE 1 #define BUFMAX 2048 +static_assert(BUFMAX > NUMREGBYTES, + "As per KGDB documentation, BUFMAX must be larger than NUMREGBYTES"); #ifdef CONFIG_RISCV_ISA_C #define BREAK_INSTR_SIZE 2 #else @@ -97,6 +101,7 @@ extern unsigned long kgdb_compiled_break; #define DBG_REG_STATUS_OFF 33 #define DBG_REG_BADADDR_OFF 34 #define DBG_REG_CAUSE_OFF 35 +/* NOTE: increase DBG_MAX_REG_NUM if you add more values here. */ extern const char riscv_gdb_stub_feature[64]; -- 2.47.3