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authorGabriel Krisman Bertazi <krisman@collabora.com>2020-10-03 23:25:32 -0400
committerThomas Gleixner <tglx@linutronix.de>2020-10-26 13:46:46 +0100
commit2424b14605c71a7187c14edd525044eb36bdea47 (patch)
treeba9a94d548fafade96dddbe8bf64c29ebd7f2332
parentelf: Expose ELF header in compat_start_thread() (diff)
downloadlinux-dev-2424b14605c71a7187c14edd525044eb36bdea47.tar.xz
linux-dev-2424b14605c71a7187c14edd525044eb36bdea47.zip
x86/elf: Use e_machine to select start_thread for x32
Since TIF_X32 is going away, avoid using it to find the ELF type in compat_start_thread. According to SysV AMD64 ABI Draft, an AMD64 ELF object using ILP32 must have ELFCLASS32 with (E_MACHINE == EM_X86_64), so use that ELF field to differentiate a x32 object from a IA32 object when executing start_thread() in compat mode. Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20201004032536.1229030-7-krisman@collabora.com
-rw-r--r--arch/x86/include/asm/elf.h5
-rw-r--r--arch/x86/kernel/process_64.c5
2 files changed, 5 insertions, 5 deletions
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 9220efc65d78..109697a19eb1 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -186,8 +186,9 @@ static inline void elf_common_init(struct thread_struct *t,
#define COMPAT_ELF_PLAT_INIT(regs, load_addr) \
elf_common_init(&current->thread, regs, __USER_DS)
-void compat_start_thread(struct pt_regs *regs, u32 new_ip, u32 new_sp);
-#define compat_start_thread compat_start_thread
+void compat_start_thread(struct pt_regs *regs, u32 new_ip, u32 new_sp, bool x32);
+#define COMPAT_START_THREAD(ex, regs, new_ip, new_sp) \
+ compat_start_thread(regs, new_ip, new_sp, ex->e_machine == EM_X86_64)
void set_personality_ia32(bool);
#define COMPAT_SET_PERSONALITY(ex) \
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index df342bedea88..5fb4103101f5 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -511,11 +511,10 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
EXPORT_SYMBOL_GPL(start_thread);
#ifdef CONFIG_COMPAT
-void compat_start_thread(struct pt_regs *regs, u32 new_ip, u32 new_sp)
+void compat_start_thread(struct pt_regs *regs, u32 new_ip, u32 new_sp, bool x32)
{
start_thread_common(regs, new_ip, new_sp,
- test_thread_flag(TIF_X32)
- ? __USER_CS : __USER32_CS,
+ x32 ? __USER_CS : __USER32_CS,
__USER_DS, __USER_DS);
}
#endif