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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-05-17 21:08:29 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-05-17 21:08:29 +0300 |
| commit | 43567139f5f3808cda4f61c956576f8a4f2232cb (patch) | |
| tree | a878bdae763213bbde2d1deaab2c7a7f102d0d90 /arch | |
| parent | 5a9ffb954a3933d7867f4341684a23e008d6839b (diff) | |
| parent | a9a3ed1eff3601b63aea4fb462d8b3b92c7c1e7e (diff) | |
| download | linux-43567139f5f3808cda4f61c956576f8a4f2232cb.tar.xz | |
Merge tag 'x86_urgent_for_v5.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fix from Borislav Petkov:
"A single fix for early boot crashes of kernels built with gcc10 and
stack protector enabled"
* tag 'x86_urgent_for_v5.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86: Fix early boot crash on gcc-10, third try
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/stackprotector.h | 7 | ||||
| -rw-r--r-- | arch/x86/kernel/smpboot.c | 8 | ||||
| -rw-r--r-- | arch/x86/xen/smp_pv.c | 1 |
3 files changed, 15 insertions, 1 deletions
diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h index 91e29b6a86a5..9804a7957f4e 100644 --- a/arch/x86/include/asm/stackprotector.h +++ b/arch/x86/include/asm/stackprotector.h @@ -55,8 +55,13 @@ /* * Initialize the stackprotector canary value. * - * NOTE: this must only be called from functions that never return, + * NOTE: this must only be called from functions that never return * and it must always be inlined. + * + * In addition, it should be called from a compilation unit for which + * stack protector is disabled. Alternatively, the caller should not end + * with a function call which gets tail-call optimized as that would + * lead to checking a modified canary value. */ static __always_inline void boot_init_stack_canary(void) { diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 8c89e4d9ad28..2f24c334a938 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -266,6 +266,14 @@ static void notrace start_secondary(void *unused) wmb(); cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); + + /* + * Prevent tail call to cpu_startup_entry() because the stack protector + * guard has been changed a couple of function calls up, in + * boot_init_stack_canary() and must not be checked before tail calling + * another function. + */ + prevent_tail_call_optimization(); } /** diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c index 8fb8a50a28b4..f2adb63b2d7c 100644 --- a/arch/x86/xen/smp_pv.c +++ b/arch/x86/xen/smp_pv.c @@ -93,6 +93,7 @@ asmlinkage __visible void cpu_bringup_and_idle(void) cpu_bringup(); boot_init_stack_canary(); cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); + prevent_tail_call_optimization(); } void xen_smp_intr_free_pv(unsigned int cpu) |