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ARCv3: r13 register changes in accordance with ABI
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For the ARCv3 architecture, changes have occurred regarding the r13 registry
in the ABI. Now register r13 from callee saved has become a scratch register.
This patch moves r13 in the corresponding structures and makes changes
in functions for proper saving and restoring user context.

We also saving and restoring missed r58/r59 registers when signal handling.
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@xxkent
xxkent committed Jun 13, 2024
1 parent 613326e commit 8fbed42
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Showing 3 changed files with 24 additions and 8 deletions.
8 changes: 8 additions & 0 deletions arch/arc/include/uapi/asm/ptrace.h
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Original file line number Diff line number Diff line change
Expand Up @@ -37,13 +37,21 @@ struct user_regs_struct {
struct {
unsigned long bta, lp_start, lp_end, lp_count;
unsigned long status32, ret, blink, fp, gp;
#ifdef __ARC64__

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@shahab-vahedi

shahab-vahedi Jun 18, 2024 •
edited
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@xxkent I think the following is a cleaner approach

struct user_regs_struct {

	unsigned long pad;
	struct {
		unsigned long bta, lp_start, lp_end, lp_count;
		unsigned long status32, ret, blink, fp, gp;
#ifdef __ARC64__
		unsigned long r13;
#endif
		unsigned long r12, r11, r10, r9, r8, r7, r6, r5, r4, r3, r2, r1, r0;
		unsigned long sp;
	} scratch;
	unsigned long pad2;
	struct {
		unsigned long r25, r24, r23, r22, r21, r20;
		unsigned long r19, r18, r17, r16, r15, r14;
#ifndef __ARC64__
		unsigned long r13;
#endif
	} callee;
	unsigned long efa;	/* break pt addr, for break points in delay slots */
	unsigned long stop_pc;	/* give dbg stop_pc after ensuring brkpt trap */
};
unsigned long r13, r12, r11, r10, r9, r8, r7, r6, r5, r4, r3, r2, r1, r0;
#else
unsigned long r12, r11, r10, r9, r8, r7, r6, r5, r4, r3, r2, r1, r0;
#endif
unsigned long sp;
} scratch;
unsigned long pad2;
struct {
unsigned long r25, r24, r23, r22, r21, r20;
#ifdef __ARC64__
unsigned long r19, r18, r17, r16, r15, r14;
#else
unsigned long r19, r18, r17, r16, r15, r14, r13;
#endif
} callee;
unsigned long efa; /* break pt addr, for break points in delay slots */
unsigned long stop_pc; /* give dbg stop_pc after ensuring brkpt trap */
Expand Down
14 changes: 8 additions & 6 deletions arch/arc/kernel/ptrace.c
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,9 @@ static int genregs_get(struct task_struct *target,
membuf_store(&to, ptregs->blink);
membuf_store(&to, ptregs->fp);
membuf_store(&to, ptregs->gp);
#ifdef CONFIG_ISA_ARCV3
membuf_store(&to, ptregs->r13);
#endif
membuf_store(&to, ptregs->r12);
membuf_store(&to, ptregs->r11);
membuf_store(&to, ptregs->r10);
Expand Down Expand Up @@ -68,9 +71,7 @@ static int genregs_get(struct task_struct *target,
membuf_store(&to, cregs->r16);
membuf_store(&to, cregs->r15);
membuf_store(&to, cregs->r14);
#ifdef CONFIG_ISA_ARCV3
membuf_store(&to, ptregs->r13);
#else
#ifndef CONFIG_ISA_ARCV3
membuf_store(&to, cregs->r13);
#endif
membuf_store(&to, target->thread.fault_address); // efa
Expand Down Expand Up @@ -134,6 +135,9 @@ static int genregs_set(struct task_struct *target,
REG_IN_ONE(scratch.blink, &ptregs->blink);
REG_IN_ONE(scratch.fp, &ptregs->fp);
REG_IN_ONE(scratch.gp, &ptregs->gp);
#ifdef CONFIG_ISA_ARCV3
REG_IN_ONE(scratch.r13, &ptregs->r13);
#endif
REG_IN_ONE(scratch.r12, &ptregs->r12);
REG_IN_ONE(scratch.r11, &ptregs->r11);
REG_IN_ONE(scratch.r10, &ptregs->r10);
Expand Down Expand Up @@ -164,9 +168,7 @@ static int genregs_set(struct task_struct *target,
REG_IN_ONE(callee.r15, &cregs->r15);
REG_IN_ONE(callee.r14, &cregs->r14);

#ifdef CONFIG_ISA_ARCV3
REG_IN_ONE(callee.r13, &ptregs->r13);
#else
#ifndef CONFIG_ISA_ARCV3
REG_IN_ONE(callee.r13, &cregs->r13);
#endif

Expand Down
10 changes: 8 additions & 2 deletions arch/arc/kernel/signal.c
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Original file line number Diff line number Diff line change
Expand Up @@ -129,6 +129,9 @@ stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,
uregs.scratch.blink = regs->blink;
uregs.scratch.fp = regs->fp;
uregs.scratch.gp = regs->gp;
#ifdef CONFIG_ISA_ARCV3
uregs.scratch.r13 = regs->r13;
#endif
uregs.scratch.r12 = regs->r12;
uregs.scratch.r11 = regs->r11;
uregs.scratch.r10 = regs->r10;
Expand All @@ -147,7 +150,7 @@ stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,
err = __copy_to_user(&(sf->uc.uc_mcontext.regs.scratch), &uregs.scratch,
sizeof(sf->uc.uc_mcontext.regs.scratch));

if (is_isa_arcv2())
if (!is_isa_arcompact())
err |= save_arcv2_regs(&(sf->uc.uc_mcontext), regs);

err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));
Expand All @@ -166,7 +169,7 @@ static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
&(sf->uc.uc_mcontext.regs.scratch),
sizeof(sf->uc.uc_mcontext.regs.scratch));

if (is_isa_arcv2())
if (!is_isa_arcompact())
err |= restore_arcv2_regs(&(sf->uc.uc_mcontext), regs);

if (err)
Expand All @@ -184,6 +187,9 @@ static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
regs->blink = uregs.scratch.blink;
regs->fp = uregs.scratch.fp;
regs->gp = uregs.scratch.gp;
#ifdef CONFIG_ISA_ARCV3
regs->r13 = uregs.scratch.r13;
#endif
regs->r12 = uregs.scratch.r12;
regs->r11 = uregs.scratch.r11;
regs->r10 = uregs.scratch.r10;
Expand Down

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