On 10/07/2019 14:25, Will Deacon wrote:
On Wed, Jul 10, 2019 at 02:04:52PM +0100, Vincenzo Frascino wrote:
Prior to the introduction of Unified vDSO support and compat layer for vDSO on arm64, AT_SYSINFO_EHDR was not defined for compat tasks. In the current implementation, AT_SYSINFO_EHDR is defined even if the compat vdso layer is not built and this causes a regression in the expected behavior of the ABI.
Restore the ABI behavior making sure that AT_SYSINFO_EHDR for compat tasks is defined only when CONFIG_GENERIC_COMPAT_VDSO and CONFIG_COMPAT_VDSO are enabled.
I think you could do a better job in the changelog of explaining what's actually going on here. The problem seems to be that you're advertising the presence of a non-existent vDSO to userspace.
Reported-by: John Stultz john.stultz@linaro.org Signed-off-by: Vincenzo Frascino vincenzo.frascino@arm.com
arch/arm64/include/asm/elf.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h index 3c7037c6ba9b..b7992bb9d414 100644 --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -202,7 +202,7 @@ typedef compat_elf_greg_t compat_elf_gregset_t[COMPAT_ELF_NGREG]; ({ \ set_thread_flag(TIF_32BIT); \ }) -#ifdef CONFIG_GENERIC_COMPAT_VDSO +#if defined(CONFIG_COMPAT_VDSO) && defined(CONFIG_GENERIC_COMPAT_VDSO)
Can't this just be #ifdef CONFIG_COMPAT_VDSO ?
Yes, I realized it after I pushed the patch that CONFIG_GENERIC_COMPAT_VDSO can be removed. Posting v2 shortly.
John -- can you give this a whirl, please?
Cheers,
Will