diff options
| author | Nicholas Piggin <npiggin@gmail.com> | 2020-05-07 22:13:32 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-05-15 11:58:54 +1000 |
| commit | 4e0e45b07d790253643ee05300784ab2156e2d5e (patch) | |
| tree | 8945f0e66bed685345be9fa12472e21893db7a41 /arch/powerpc/include/asm/ptrace.h | |
| parent | 912237ea166428edcbf3c137adf12cb987c477f2 (diff) | |
powerpc: Use trap metadata to prevent double restart rather than zeroing trap
It's not very nice to zero trap for this, because then system calls no
longer have trap_is_syscall(regs) invariant, and we can't distinguish
between sc and scv system calls (in a later patch).
Take one last unused bit from the low bits of the pt_regs.trap word
for this instead. There is not a really good reason why it should be
in trap as opposed to another field, but trap has some concept of
flags and it exists. Ideally I think we would move trap to 2-byte
field and have 2 more bytes available independently.
Add a selftests case for this, which can be seen to fail if
trap_norestart() is changed to return false.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Make them static inlines]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200507121332.2233629-4-mpe@ellerman.id.au
Diffstat (limited to 'arch/powerpc/include/asm/ptrace.h')
| -rw-r--r-- | arch/powerpc/include/asm/ptrace.h | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h index 5db45790a087..ac3970fff0d5 100644 --- a/arch/powerpc/include/asm/ptrace.h +++ b/arch/powerpc/include/asm/ptrace.h @@ -182,13 +182,13 @@ extern int ptrace_put_reg(struct task_struct *task, int regno, #ifdef __powerpc64__ #ifdef CONFIG_PPC_BOOK3S -#define TRAP_FLAGS_MASK 0 -#define TRAP(regs) ((regs)->trap) +#define TRAP_FLAGS_MASK 0x10 +#define TRAP(regs) ((regs)->trap & ~TRAP_FLAGS_MASK) #define FULL_REGS(regs) true #define SET_FULL_REGS(regs) do { } while (0) #else -#define TRAP_FLAGS_MASK 0x1 -#define TRAP(regs) ((regs)->trap & ~0x1) +#define TRAP_FLAGS_MASK 0x11 +#define TRAP(regs) ((regs)->trap & ~TRAP_FLAGS_MASK) #define FULL_REGS(regs) (((regs)->trap & 1) == 0) #define SET_FULL_REGS(regs) ((regs)->trap |= 1) #endif @@ -202,8 +202,8 @@ extern int ptrace_put_reg(struct task_struct *task, int regno, * On 4xx we use the next bit to indicate whether the exception * is a critical exception (1 means it is). */ -#define TRAP_FLAGS_MASK 0xF -#define TRAP(regs) ((regs)->trap & ~0xF) +#define TRAP_FLAGS_MASK 0x1F +#define TRAP(regs) ((regs)->trap & ~TRAP_FLAGS_MASK) #define FULL_REGS(regs) (((regs)->trap & 1) == 0) #define SET_FULL_REGS(regs) ((regs)->trap |= 1) #define IS_CRITICAL_EXC(regs) (((regs)->trap & 2) != 0) @@ -227,6 +227,16 @@ static inline bool trap_is_syscall(struct pt_regs *regs) return TRAP(regs) == 0xc00; } +static inline bool trap_norestart(struct pt_regs *regs) +{ + return regs->trap & 0x10; +} + +static inline void set_trap_norestart(struct pt_regs *regs) +{ + regs->trap |= 0x10; +} + #define arch_has_single_step() (1) #ifndef CONFIG_BOOK3S_601 #define arch_has_block_step() (true) |