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powerpc: move norestart trap flag to bit 0 

Compact the trap flags down to use the low 4 bits of regs.trap.

A few 64e interrupt trap numbers set bit 4. Although they tended to be
trivial so it wasn't a real problem[1], it is not the right thing to do,
and confusing.

[*] E.g., 0x310 hypercall goes to unknown_exception, which prints
    regs->trap directly so 0x310 will appear fine, and only the syscall
    interrupt will test norestart, so it won't be confused by 0x310.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210316104206.407354-12-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2021-03-16 20:42:05 +10:00 committed by Michael Ellerman
parent 8dc7f0229b
commit 8f6cc75a97
1 changed files with 11 additions and 6 deletions
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17
arch/powerpc/include/asm/ptrace.h
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@ -185,20 +185,25 @@ static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
#define current_pt_regs() \
((struct pt_regs *)((unsigned long)task_stack_page(current) + THREAD_SIZE) - 1)
/*
* The 4 low bits (0xf) are available as flags to overload the trap word,
* because interrupt vectors have minimum alignment of 0x10. TRAP_FLAGS_MASK
* must cover the bits used as flags, including bit 0 which is used as the
* "norestart" bit.
*/
#ifdef __powerpc64__
#define TRAP_FLAGS_MASK 0x10
#define TRAP(regs) ((regs)->trap & ~TRAP_FLAGS_MASK)
#define TRAP_FLAGS_MASK 0x1
#else
/*
* On 4xx we use bit 1 in the trap word to indicate whether the exception
* is a critical exception (1 means it is).
*/
#define TRAP_FLAGS_MASK 0x1E
#define TRAP(regs) ((regs)->trap & ~TRAP_FLAGS_MASK)
#define TRAP_FLAGS_MASK 0xf
#define IS_CRITICAL_EXC(regs) (((regs)->trap & 2) != 0)
#define IS_MCHECK_EXC(regs) (((regs)->trap & 4) != 0)
#define IS_DEBUG_EXC(regs) (((regs)->trap & 8) != 0)
#endif /* __powerpc64__ */
#define TRAP(regs) ((regs)->trap & ~TRAP_FLAGS_MASK)
static __always_inline void set_trap(struct pt_regs *regs, unsigned long val)
{
@ -222,12 +227,12 @@ static inline bool trap_is_syscall(struct pt_regs *regs)
static inline bool trap_norestart(struct pt_regs *regs)
{
return regs->trap & 0x10;
return regs->trap & 0x1;
}
static __always_inline void set_trap_norestart(struct pt_regs *regs)
{
regs->trap |= 0x10;
regs->trap |= 0x1;
}
#define arch_has_single_step() (1)