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author | Dave Martin <Dave.Martin@arm.com> | 2017-06-21 16:00:42 +0100 |
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committer | Will Deacon <will.deacon@arm.com> | 2017-06-22 15:58:19 +0100 |
commit | af66b2d88a76574d55e81d712292abd34beb6178 (patch) | |
tree | c74ef3292b52b8bba5a1d92d7c654b73fd9073dd | |
parent | f5d284900c0f960e318a063f4c40826b6e3aa6a8 (diff) | |
download | linux-af66b2d88a76574d55e81d712292abd34beb6178.tar.gz linux-af66b2d88a76574d55e81d712292abd34beb6178.tar.bz2 linux-af66b2d88a76574d55e81d712292abd34beb6178.zip |
arm64: ptrace: Fix VFP register dumping in compat coredumps
Currently, VFP registers are omitted from coredumps for compat
processes, due to a bug in the REGSET_COMPAT_VFP regset
implementation.
compat_vfp_get() needs to transfer non-contiguous data from
thread_struct.fpsimd_state, and uses put_user() to handle the
offending trailing word (FPSCR). This fails when copying to a
kernel address (i.e., kbuf && !ubuf), which is what happens when
dumping core. As a result, the ELF coredump core code silently
omits the NT_ARM_VFP note from the dump.
It would be possible to work around this with additional special
case code for the put_user(), but since user_regset_copyout() is
explicitly designed to handle this scenario it is cleaner to port
the put_user() to a user_regset_copyout() call, which this patch
does.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
-rw-r--r-- | arch/arm64/kernel/ptrace.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index c142459a88f3..0e5aaec5b751 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -894,7 +894,7 @@ static int compat_vfp_get(struct task_struct *target, { struct user_fpsimd_state *uregs; compat_ulong_t fpscr; - int ret; + int ret, vregs_end_pos; uregs = &target->thread.fpsimd_state.user_fpsimd; @@ -902,13 +902,16 @@ static int compat_vfp_get(struct task_struct *target, * The VFP registers are packed into the fpsimd_state, so they all sit * nicely together for us. We just need to create the fpscr separately. */ - ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0, - VFP_STATE_SIZE - sizeof(compat_ulong_t)); + vregs_end_pos = VFP_STATE_SIZE - sizeof(compat_ulong_t); + ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, + 0, vregs_end_pos); if (count && !ret) { fpscr = (uregs->fpsr & VFP_FPSCR_STAT_MASK) | (uregs->fpcr & VFP_FPSCR_CTRL_MASK); - ret = put_user(fpscr, (compat_ulong_t *)ubuf); + + ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &fpscr, + vregs_end_pos, VFP_STATE_SIZE); } return ret; |