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include: sbi: Use array for struct sbi_trap_regs and GET/SET macros

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Rather than hand-rolling scaled pointer arithmetic with casts and
shifts, let the compiler do so by indexing an array of GPRs, taking
advantage of the language's type system to scale based on whatever type
the register happens to be. This makes it easier to support CHERI where
the registers are capabilities, not plain integers, and so this pointer
arithmetic would need to change (and currently REGBYTES is both the size
of a register and the size of an integer word upstream).

Signed-off-by: Jessica Clarke <jrtc27@jrtc27.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20250709232932.37622-1-jrtc27@jrtc27.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Jessica Clarke
2025-07-10 00:29:28 +01:00
committed by Anup Patel
parent 0b7c2e0d60
commit ffd3ed976d
2 changed files with 92 additions and 81 deletions
Download Patch File Download Diff File Expand all files Collapse all files

148
include/sbi/sbi_trap.h
View File

@@ -127,70 +127,75 @@
/** Representation of register state at time of trap/interrupt */
struct sbi_trap_regs {
/** zero register state */
unsigned long zero;
/** ra register state */
unsigned long ra;
/** sp register state */
unsigned long sp;
/** gp register state */
unsigned long gp;
/** tp register state */
unsigned long tp;
/** t0 register state */
unsigned long t0;
/** t1 register state */
unsigned long t1;
/** t2 register state */
unsigned long t2;
/** s0 register state */
unsigned long s0;
/** s1 register state */
unsigned long s1;
/** a0 register state */
unsigned long a0;
/** a1 register state */
unsigned long a1;
/** a2 register state */
unsigned long a2;
/** a3 register state */
unsigned long a3;
/** a4 register state */
unsigned long a4;
/** a5 register state */
unsigned long a5;
/** a6 register state */
unsigned long a6;
/** a7 register state */
unsigned long a7;
/** s2 register state */
unsigned long s2;
/** s3 register state */
unsigned long s3;
/** s4 register state */
unsigned long s4;
/** s5 register state */
unsigned long s5;
/** s6 register state */
unsigned long s6;
/** s7 register state */
unsigned long s7;
/** s8 register state */
unsigned long s8;
/** s9 register state */
unsigned long s9;
/** s10 register state */
unsigned long s10;
/** s11 register state */
unsigned long s11;
/** t3 register state */
unsigned long t3;
/** t4 register state */
unsigned long t4;
/** t5 register state */
unsigned long t5;
/** t6 register state */
unsigned long t6;
union {
unsigned long gprs[32];
struct {
/** zero register state */
unsigned long zero;
/** ra register state */
unsigned long ra;
/** sp register state */
unsigned long sp;
/** gp register state */
unsigned long gp;
/** tp register state */
unsigned long tp;
/** t0 register state */
unsigned long t0;
/** t1 register state */
unsigned long t1;
/** t2 register state */
unsigned long t2;
/** s0 register state */
unsigned long s0;
/** s1 register state */
unsigned long s1;
/** a0 register state */
unsigned long a0;
/** a1 register state */
unsigned long a1;
/** a2 register state */
unsigned long a2;
/** a3 register state */
unsigned long a3;
/** a4 register state */
unsigned long a4;
/** a5 register state */
unsigned long a5;
/** a6 register state */
unsigned long a6;
/** a7 register state */
unsigned long a7;
/** s2 register state */
unsigned long s2;
/** s3 register state */
unsigned long s3;
/** s4 register state */
unsigned long s4;
/** s5 register state */
unsigned long s5;
/** s6 register state */
unsigned long s6;
/** s7 register state */
unsigned long s7;
/** s8 register state */
unsigned long s8;
/** s9 register state */
unsigned long s9;
/** s10 register state */
unsigned long s10;
/** s11 register state */
unsigned long s11;
/** t3 register state */
unsigned long t3;
/** t4 register state */
unsigned long t4;
/** t5 register state */
unsigned long t5;
/** t6 register state */
unsigned long t6;
};
};
/** mepc register state */
unsigned long mepc;
/** mstatus register state */
@@ -199,6 +204,21 @@ struct sbi_trap_regs {
unsigned long mstatusH;
};
_Static_assert(
sizeof(((struct sbi_trap_regs *)0)->gprs) ==
offsetof(struct sbi_trap_regs, t6) +
sizeof(((struct sbi_trap_regs *)0)->t6),
"struct sbi_trap_regs's layout differs between gprs and named members");
#define REG_VAL(idx, regs) ((regs)->gprs[(idx)])
#define GET_RS1(insn, regs) REG_VAL(GET_RS1_NUM(insn), regs)
#define GET_RS2(insn, regs) REG_VAL(GET_RS2_NUM(insn), regs)
#define GET_RS1S(insn, regs) REG_VAL(GET_RS1S_NUM(insn), regs)
#define GET_RS2S(insn, regs) REG_VAL(GET_RS2S_NUM(insn), regs)
#define GET_RS2C(insn, regs) REG_VAL(GET_RS2C_NUM(insn), regs)
#define SET_RD(insn, regs, val) (REG_VAL(GET_RD_NUM(insn), regs) = (val))
/** Representation of trap details */
struct sbi_trap_info {
/** cause Trap exception cause */