* [PATCH] UefiCpuPkg/CpuMpPei: suppress compiler complaining
@ 2018-09-11 4:47 Jian J Wang
2018-09-11 14:55 ` Laszlo Ersek
0 siblings, 1 reply; 3+ messages in thread
From: Jian J Wang @ 2018-09-11 4:47 UTC (permalink / raw)
To: edk2-devel; +Cc: Dandan Bi, Hao A Wu
BZ#: https://bugzilla.tianocore.org/show_bug.cgi?id=1166
Cc: Dandan Bi <dandan.bi@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
UefiCpuPkg/CpuMpPei/CpuPaging.c | 23 ++++++++++++++++-------
1 file changed, 16 insertions(+), 7 deletions(-)
diff --git a/UefiCpuPkg/CpuMpPei/CpuPaging.c b/UefiCpuPkg/CpuMpPei/CpuPaging.c
index bcb942a8e5..a63421a1af 100644
--- a/UefiCpuPkg/CpuMpPei/CpuPaging.c
+++ b/UefiCpuPkg/CpuMpPei/CpuPaging.c
@@ -517,7 +517,7 @@ GetStackBase (
IN OUT VOID *Buffer
)
{
- EFI_PHYSICAL_ADDRESS StackBase;
+ volatile EFI_PHYSICAL_ADDRESS StackBase;
StackBase = (EFI_PHYSICAL_ADDRESS)(UINTN)&StackBase;
StackBase += BASE_4KB;
@@ -554,6 +554,8 @@ SetupStackGuardPage (
MpInitLibGetNumberOfProcessors(&NumberOfProcessors, NULL);
MpInitLibWhoAmI (&Bsp);
for (Index = 0; Index < NumberOfProcessors; ++Index) {
+ StackBase = 0;
+
if (Index == Bsp) {
Hob.Raw = GetHobList ();
while ((Hob.Raw = GetNextHob (EFI_HOB_TYPE_MEMORY_ALLOCATION, Hob.Raw)) != NULL) {
@@ -570,12 +572,19 @@ SetupStackGuardPage (
//
MpInitLibStartupThisAP(GetStackBase, Index, NULL, 0, (VOID *)&StackBase, NULL);
}
- //
- // Set Guard page at stack base address.
- //
- ConvertMemoryPageAttributes(StackBase, EFI_PAGE_SIZE, 0);
- DEBUG ((DEBUG_INFO, "Stack Guard set at %lx [cpu%lu]!\n",
- (UINT64)StackBase, (UINT64)Index));
+
+ if (StackBase == 0) {
+ DEBUG ((DEBUG_ERROR, "Stack base address was not found for [cpu%lu]!\n",
+ (UINT64)Index));
+ ASSERT(StackBase != 0);
+ } else {
+ //
+ // Set Guard page at stack base address.
+ //
+ ConvertMemoryPageAttributes(StackBase, EFI_PAGE_SIZE, 0);
+ DEBUG ((DEBUG_INFO, "Stack Guard set at %lx [cpu%lu]!\n",
+ (UINT64)StackBase, (UINT64)Index));
+ }
}
//
--
2.16.2.windows.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] UefiCpuPkg/CpuMpPei: suppress compiler complaining
2018-09-11 4:47 [PATCH] UefiCpuPkg/CpuMpPei: suppress compiler complaining Jian J Wang
@ 2018-09-11 14:55 ` Laszlo Ersek
2018-09-12 0:23 ` Wang, Jian J
0 siblings, 1 reply; 3+ messages in thread
From: Laszlo Ersek @ 2018-09-11 14:55 UTC (permalink / raw)
To: Jian J Wang, edk2-devel; +Cc: Hao A Wu, Dandan Bi, Eric Dong
Jian,
On 09/11/18 06:47, Jian J Wang wrote:
> BZ#: https://bugzilla.tianocore.org/show_bug.cgi?id=1166
>
> Cc: Dandan Bi <dandan.bi@intel.com>
> Cc: Hao A Wu <hao.a.wu@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
> ---
> UefiCpuPkg/CpuMpPei/CpuPaging.c | 23 ++++++++++++++++-------
> 1 file changed, 16 insertions(+), 7 deletions(-)
(1) Please remember to CC the package maintainers / reviewers on
patches. "Maintainers.txt" lists Eric (M) and myself (R) for UefiCpuPkg.
It's OK to CC other people as well, of course.
(2) Bug 1166 mentions "warning C4701: potentially uninitialized local
variable 'StackBase' used".
If that warning is invalid (= the variable can never be read
unassigned), then we have some suggested language for that; please see
<https://bugzilla.tianocore.org/show_bug.cgi?id=607>.
Furthermore:
>
> diff --git a/UefiCpuPkg/CpuMpPei/CpuPaging.c b/UefiCpuPkg/CpuMpPei/CpuPaging.c
> index bcb942a8e5..a63421a1af 100644
> --- a/UefiCpuPkg/CpuMpPei/CpuPaging.c
> +++ b/UefiCpuPkg/CpuMpPei/CpuPaging.c
> @@ -517,7 +517,7 @@ GetStackBase (
> IN OUT VOID *Buffer
> )
> {
> - EFI_PHYSICAL_ADDRESS StackBase;
> + volatile EFI_PHYSICAL_ADDRESS StackBase;
(3) "volatile" seems unrelated; I suggest dropping it.
(Especially without the comment mentioned in TianoCore#607, "volatile"
is totally unjustified and confusing.)
>
> StackBase = (EFI_PHYSICAL_ADDRESS)(UINTN)&StackBase;
> StackBase += BASE_4KB;
> @@ -554,6 +554,8 @@ SetupStackGuardPage (
> MpInitLibGetNumberOfProcessors(&NumberOfProcessors, NULL);
> MpInitLibWhoAmI (&Bsp);
> for (Index = 0; Index < NumberOfProcessors; ++Index) {
> + StackBase = 0;
> +
> if (Index == Bsp) {
> Hob.Raw = GetHobList ();
> while ((Hob.Raw = GetNextHob (EFI_HOB_TYPE_MEMORY_ALLOCATION, Hob.Raw)) != NULL) {
> @@ -570,12 +572,19 @@ SetupStackGuardPage (
> //
> MpInitLibStartupThisAP(GetStackBase, Index, NULL, 0, (VOID *)&StackBase, NULL);
> }
> - //
> - // Set Guard page at stack base address.
> - //
> - ConvertMemoryPageAttributes(StackBase, EFI_PAGE_SIZE, 0);
> - DEBUG ((DEBUG_INFO, "Stack Guard set at %lx [cpu%lu]!\n",
> - (UINT64)StackBase, (UINT64)Index));
> +
> + if (StackBase == 0) {
> + DEBUG ((DEBUG_ERROR, "Stack base address was not found for [cpu%lu]!\n",
> + (UINT64)Index));
> + ASSERT(StackBase != 0);
(4) On the other hand, if it *can* happen in practice that the stack
base is not found (and in that case, we should halt), then:
* the subject line is wrong, because the compiler warning is *valid*,
and we don't suppress it, but fix the issue caught by the compiler;
* we must not proceed in a RELEASE build either, therefore an ASSERT is
insufficient. A CpuDeadLoop() is necessary.
(Again, this only applies if StackBase may be zero here by design.)
Thanks
Laszlo
> + } else {
> + //
> + // Set Guard page at stack base address.
> + //
> + ConvertMemoryPageAttributes(StackBase, EFI_PAGE_SIZE, 0);
> + DEBUG ((DEBUG_INFO, "Stack Guard set at %lx [cpu%lu]!\n",
> + (UINT64)StackBase, (UINT64)Index));
> + }
> }
>
> //
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] UefiCpuPkg/CpuMpPei: suppress compiler complaining
2018-09-11 14:55 ` Laszlo Ersek
@ 2018-09-12 0:23 ` Wang, Jian J
0 siblings, 0 replies; 3+ messages in thread
From: Wang, Jian J @ 2018-09-12 0:23 UTC (permalink / raw)
To: Laszlo Ersek, edk2-devel@lists.01.org; +Cc: Wu, Hao A, Bi, Dandan, Dong, Eric
Laszlo,
Thanks for the comments.
(1) Sure. My fault. I thought it’s just very small change for compiler warning.
(2) From language point view, it’s a valid warning. But from code logic, it’s invalid.
(3) Agree. It’ll be dropped.
(4) Agree. I’ll change it.
Regards,
Jian
From: Laszlo Ersek [mailto:lersek@redhat.com]
Sent: Tuesday, September 11, 2018 10:56 PM
To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org
Cc: Wu, Hao A <hao.a.wu@intel.com>; Bi, Dandan <dandan.bi@intel.com>; Dong, Eric <eric.dong@intel.com>
Subject: Re: [edk2] [PATCH] UefiCpuPkg/CpuMpPei: suppress compiler complaining
Jian,
On 09/11/18 06:47, Jian J Wang wrote:
> BZ#: https://bugzilla.tianocore.org/show_bug.cgi?id=1166
>
> Cc: Dandan Bi <dandan.bi@intel.com<mailto:dandan.bi@intel.com>>
> Cc: Hao A Wu <hao.a.wu@intel.com<mailto:hao.a.wu@intel.com>>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jian J Wang <jian.j.wang@intel.com<mailto:jian.j.wang@intel.com>>
> ---
> UefiCpuPkg/CpuMpPei/CpuPaging.c | 23 ++++++++++++++++-------
> 1 file changed, 16 insertions(+), 7 deletions(-)
(1) Please remember to CC the package maintainers / reviewers on
patches. "Maintainers.txt" lists Eric (M) and myself (R) for UefiCpuPkg.
It's OK to CC other people as well, of course.
(2) Bug 1166 mentions "warning C4701: potentially uninitialized local
variable 'StackBase' used".
If that warning is invalid (= the variable can never be read
unassigned), then we have some suggested language for that; please see
<https://bugzilla.tianocore.org/show_bug.cgi?id=607>.
Furthermore:
>
> diff --git a/UefiCpuPkg/CpuMpPei/CpuPaging.c b/UefiCpuPkg/CpuMpPei/CpuPaging.c
> index bcb942a8e5..a63421a1af 100644
> --- a/UefiCpuPkg/CpuMpPei/CpuPaging.c
> +++ b/UefiCpuPkg/CpuMpPei/CpuPaging.c
> @@ -517,7 +517,7 @@ GetStackBase (
> IN OUT VOID *Buffer
> )
> {
> - EFI_PHYSICAL_ADDRESS StackBase;
> + volatile EFI_PHYSICAL_ADDRESS StackBase;
(3) "volatile" seems unrelated; I suggest dropping it.
(Especially without the comment mentioned in TianoCore#607, "volatile"
is totally unjustified and confusing.)
>
> StackBase = (EFI_PHYSICAL_ADDRESS)(UINTN)&StackBase;
> StackBase += BASE_4KB;
> @@ -554,6 +554,8 @@ SetupStackGuardPage (
> MpInitLibGetNumberOfProcessors(&NumberOfProcessors, NULL);
> MpInitLibWhoAmI (&Bsp);
> for (Index = 0; Index < NumberOfProcessors; ++Index) {
> + StackBase = 0;
> +
> if (Index == Bsp) {
> Hob.Raw = GetHobList ();
> while ((Hob.Raw = GetNextHob (EFI_HOB_TYPE_MEMORY_ALLOCATION, Hob.Raw)) != NULL) {
> @@ -570,12 +572,19 @@ SetupStackGuardPage (
> //
> MpInitLibStartupThisAP(GetStackBase, Index, NULL, 0, (VOID *)&StackBase, NULL);
> }
> - //
> - // Set Guard page at stack base address.
> - //
> - ConvertMemoryPageAttributes(StackBase, EFI_PAGE_SIZE, 0);
> - DEBUG ((DEBUG_INFO, "Stack Guard set at %lx [cpu%lu]!\n",
> - (UINT64)StackBase, (UINT64)Index));
> +
> + if (StackBase == 0) {
> + DEBUG ((DEBUG_ERROR, "Stack base address was not found for [cpu%lu]!\n",
> + (UINT64)Index));
> + ASSERT(StackBase != 0);
(4) On the other hand, if it *can* happen in practice that the stack
base is not found (and in that case, we should halt), then:
* the subject line is wrong, because the compiler warning is *valid*,
and we don't suppress it, but fix the issue caught by the compiler;
* we must not proceed in a RELEASE build either, therefore an ASSERT is
insufficient. A CpuDeadLoop() is necessary.
(Again, this only applies if StackBase may be zero here by design.)
Thanks
Laszlo
> + } else {
> + //
> + // Set Guard page at stack base address.
> + //
> + ConvertMemoryPageAttributes(StackBase, EFI_PAGE_SIZE, 0);
> + DEBUG ((DEBUG_INFO, "Stack Guard set at %lx [cpu%lu]!\n",
> + (UINT64)StackBase, (UINT64)Index));
> + }
> }
>
> //
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-09-11 4:47 [PATCH] UefiCpuPkg/CpuMpPei: suppress compiler complaining Jian J Wang
2018-09-11 14:55 ` Laszlo Ersek
2018-09-12 0:23 ` Wang, Jian J
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