When upreving llvm I realised that kexec stopped working on my test platform.
The reason seems to be that due to PGO there are multiple .text sections on the purgatory, and kexec does not supports that.
Signed-off-by: Ricardo Ribalda ribalda@chromium.org --- Changes in v6: - Replace linker script with Makefile rule. Thanks Nick - Link to v5: https://lore.kernel.org/r/20230321-kexec_clang16-v5-0-5563bf7c4173@chromium....
Changes in v5: - Add warning when multiple text sections are found. Thanks Simon! - Add Fixes tag. - Link to v4: https://lore.kernel.org/r/20230321-kexec_clang16-v4-0-1340518f98e9@chromium....
Changes in v4: - Add Cc: stable - Add linker script for x86 - Add a warning when the kernel image has overlapping sections. - Link to v3: https://lore.kernel.org/r/20230321-kexec_clang16-v3-0-5f016c8d0e87@chromium....
Changes in v3: - Fix initial value. Thanks Ross! - Link to v2: https://lore.kernel.org/r/20230321-kexec_clang16-v2-0-d10e5d517869@chromium....
Changes in v2: - Fix if condition. Thanks Steven!. - Update Philipp email. Thanks Baoquan. - Link to v1: https://lore.kernel.org/r/20230321-kexec_clang16-v1-0-a768fc2c7c4d@chromium....
--- Ricardo Ribalda (4): kexec: Support purgatories with .text.hot sections x86/purgatory: Remove profile optimization flags powerpc/purgatory: Remove profile optimization flags risc/purgatory: Add linker script
arch/powerpc/purgatory/Makefile | 5 +++++ arch/riscv/purgatory/Makefile | 5 +++++ arch/x86/purgatory/Makefile | 5 +++++ kernel/kexec_file.c | 14 +++++++++++++- 4 files changed, 28 insertions(+), 1 deletion(-) --- base-commit: 58390c8ce1bddb6c623f62e7ed36383e7fa5c02f change-id: 20230321-kexec_clang16-4510c23d129c
Best regards,
Clang16 links the purgatory text in two sections when PGO is in use:
[ 1] .text PROGBITS 0000000000000000 00000040 00000000000011a1 0000000000000000 AX 0 0 16 [ 2] .rela.text RELA 0000000000000000 00003498 0000000000000648 0000000000000018 I 24 1 8 ... [17] .text.hot. PROGBITS 0000000000000000 00003220 000000000000020b 0000000000000000 AX 0 0 1 [18] .rela.text.hot. RELA 0000000000000000 00004428 0000000000000078 0000000000000018 I 24 17 8
And both of them have their range [sh_addr ... sh_addr+sh_size] on the area pointed by `e_entry`.
This causes that image->start is calculated twice, once for .text and another time for .text.hot. The second calculation leaves image->start in a random location.
Because of this, the system crashes immediately after:
kexec_core: Starting new kernel
Cc: stable@vger.kernel.org Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory") Reviewed-by: Ross Zwisler zwisler@google.com Reviewed-by: Steven Rostedt (Google) rostedt@goodmis.org Reviewed-by: Philipp Rudo prudo@redhat.com Signed-off-by: Ricardo Ribalda ribalda@chromium.org --- kernel/kexec_file.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index f989f5f1933b..69ee4a29136f 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -901,10 +901,22 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi, }
offset = ALIGN(offset, align); + + /* + * Check if the segment contains the entry point, if so, + * calculate the value of image->start based on it. + * If the compiler has produced more than one .text section + * (Eg: .text.hot), they are generally after the main .text + * section, and they shall not be used to calculate + * image->start. So do not re-calculate image->start if it + * is not set to the initial value, and warn the user so they + * have a chance to fix their purgatory's linker script. + */ if (sechdrs[i].sh_flags & SHF_EXECINSTR && pi->ehdr->e_entry >= sechdrs[i].sh_addr && pi->ehdr->e_entry < (sechdrs[i].sh_addr - + sechdrs[i].sh_size)) { + + sechdrs[i].sh_size) && + !WARN_ON(kbuf->image->start != pi->ehdr->e_entry)) { kbuf->image->start -= sechdrs[i].sh_addr; kbuf->image->start += kbuf->mem + offset; }
If PGO is enabled, the purgatory ends up with multiple .text sections. This is not supported by kexec and crashes the system.
Cc: stable@vger.kernel.org Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory") Signed-off-by: Ricardo Ribalda ribalda@chromium.org --- arch/x86/purgatory/Makefile | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile index 82fec66d46d2..7a7a4901ed41 100644 --- a/arch/x86/purgatory/Makefile +++ b/arch/x86/purgatory/Makefile @@ -14,6 +14,11 @@ $(obj)/sha256.o: $(srctree)/lib/crypto/sha256.c FORCE
CFLAGS_sha256.o := -D__DISABLE_EXPORTS
+# When profile optimization is enabled, llvm emits two different overlapping +# text sections, which is not supported by kexec. Remove profile optimization +# flags. +KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS)) + # When linking purgatory.ro with -r unresolved symbols are not checked, # also link a purgatory.chk binary without -r to check for unresolved symbols. PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
If PGO is enabled, the purgatory ends up with multiple .text sections. This is not supported by kexec and crashes the system.
Cc: stable@vger.kernel.org Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory") Signed-off-by: Ricardo Ribalda ribalda@chromium.org --- arch/powerpc/purgatory/Makefile | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/powerpc/purgatory/Makefile b/arch/powerpc/purgatory/Makefile index 6f5e2727963c..5efb164330b2 100644 --- a/arch/powerpc/purgatory/Makefile +++ b/arch/powerpc/purgatory/Makefile @@ -5,6 +5,11 @@ KCSAN_SANITIZE := n
targets += trampoline_$(BITS).o purgatory.ro
+# When profile optimization is enabled, llvm emits two different overlapping +# text sections, which is not supported by kexec. Remove profile optimization +# flags. +KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS)) + LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined
$(obj)/purgatory.ro: $(obj)/trampoline_$(BITS).o FORCE
If PGO is enabled, the purgatory ends up with multiple .text sections. This is not supported by kexec and crashes the system.
Cc: stable@vger.kernel.org Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory") Signed-off-by: Ricardo Ribalda ribalda@chromium.org --- arch/riscv/purgatory/Makefile | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile index 5730797a6b40..cf3a44121a90 100644 --- a/arch/riscv/purgatory/Makefile +++ b/arch/riscv/purgatory/Makefile @@ -35,6 +35,11 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS CFLAGS_string.o := -D__DISABLE_EXPORTS CFLAGS_ctype.o := -D__DISABLE_EXPORTS
+# When profile optimization is enabled, llvm emits two different overlapping +# text sections, which is not supported by kexec. Remove profile optimization +# flags. +KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS)) + # When linking purgatory.ro with -r unresolved symbols are not checked, # also link a purgatory.chk binary without -r to check for unresolved symbols. PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
On Mon, 01 May 2023 05:38:22 PDT (-0700), ribalda@chromium.org wrote:
If PGO is enabled, the purgatory ends up with multiple .text sections. This is not supported by kexec and crashes the system.
Cc: stable@vger.kernel.org Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory") Signed-off-by: Ricardo Ribalda ribalda@chromium.org
arch/riscv/purgatory/Makefile | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile index 5730797a6b40..cf3a44121a90 100644 --- a/arch/riscv/purgatory/Makefile +++ b/arch/riscv/purgatory/Makefile @@ -35,6 +35,11 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS CFLAGS_string.o := -D__DISABLE_EXPORTS CFLAGS_ctype.o := -D__DISABLE_EXPORTS
+# When profile optimization is enabled, llvm emits two different overlapping +# text sections, which is not supported by kexec. Remove profile optimization +# flags. +KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))
# When linking purgatory.ro with -r unresolved symbols are not checked, # also link a purgatory.chk binary without -r to check for unresolved symbols. PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
Acked-by: Palmer Dabbelt palmer@rivosinc.com
On Mon, May 1, 2023 at 5:39 AM Ricardo Ribalda ribalda@chromium.org wrote:
If PGO is enabled, the purgatory ends up with multiple .text sections. This is not supported by kexec and crashes the system.
Cc: stable@vger.kernel.org Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory") Signed-off-by: Ricardo Ribalda ribalda@chromium.org
Hi Ricardo, Thanks for the series. Does this patch 4/4 need a new online commit description? It's not adding a linker script (maybe an earlier version was).
arch/riscv/purgatory/Makefile | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile index 5730797a6b40..cf3a44121a90 100644 --- a/arch/riscv/purgatory/Makefile +++ b/arch/riscv/purgatory/Makefile @@ -35,6 +35,11 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS CFLAGS_string.o := -D__DISABLE_EXPORTS CFLAGS_ctype.o := -D__DISABLE_EXPORTS
+# When profile optimization is enabled, llvm emits two different overlapping +# text sections, which is not supported by kexec. Remove profile optimization +# flags. +KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))
# When linking purgatory.ro with -r unresolved symbols are not checked, # also link a purgatory.chk binary without -r to check for unresolved symbols. PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
-- 2.40.1.495.gc816e09b53d-goog
Hi Nick
Thanks for catching this. It should have said
risc/purgatory: Remove profile optimization flags
Will fix it on my local branch in case there is a next version of the series. Otherwise, please the maintainer fix the subject.
Thanks!
On Mon, 1 May 2023 at 18:19, Nick Desaulniers ndesaulniers@google.com wrote:
On Mon, May 1, 2023 at 5:39 AM Ricardo Ribalda ribalda@chromium.org wrote:
If PGO is enabled, the purgatory ends up with multiple .text sections. This is not supported by kexec and crashes the system.
Cc: stable@vger.kernel.org Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory") Signed-off-by: Ricardo Ribalda ribalda@chromium.org
Hi Ricardo, Thanks for the series. Does this patch 4/4 need a new online commit description? It's not adding a linker script (maybe an earlier version was).
arch/riscv/purgatory/Makefile | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile index 5730797a6b40..cf3a44121a90 100644 --- a/arch/riscv/purgatory/Makefile +++ b/arch/riscv/purgatory/Makefile @@ -35,6 +35,11 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS CFLAGS_string.o := -D__DISABLE_EXPORTS CFLAGS_ctype.o := -D__DISABLE_EXPORTS
+# When profile optimization is enabled, llvm emits two different overlapping +# text sections, which is not supported by kexec. Remove profile optimization +# flags. +KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))
# When linking purgatory.ro with -r unresolved symbols are not checked, # also link a purgatory.chk binary without -r to check for unresolved symbols. PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
-- 2.40.1.495.gc816e09b53d-goog
-- Thanks, ~Nick Desaulniers
On Mon, May 01, 2023 at 07:18:12PM +0200, Ricardo Ribalda wrote:
On Mon, 1 May 2023 at 18:19, Nick Desaulniers ndesaulniers@google.com wrote:
On Mon, May 1, 2023 at 5:39 AM Ricardo Ribalda ribalda@chromium.org wrote:
If PGO is enabled, the purgatory ends up with multiple .text sections. This is not supported by kexec and crashes the system.
Cc: stable@vger.kernel.org Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory") Signed-off-by: Ricardo Ribalda ribalda@chromium.org
Hi Ricardo, Thanks for the series. Does this patch 4/4 need a new online commit description? It's not adding a linker script (maybe an earlier version was).
Thanks for catching this. It should have said
risc/purgatory: Remove profile optimization flags
^^ Perhaps with the omitted v added too?
Also while playing the $subject nitpicking game, is it not called "profile**-guided** optimisation" (and ditto in the comments)?
Cheers, Conor.
Will fix it on my local branch in case there is a next version of the series. Otherwise, please the maintainer fix the subject.
arch/riscv/purgatory/Makefile | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile index 5730797a6b40..cf3a44121a90 100644 --- a/arch/riscv/purgatory/Makefile +++ b/arch/riscv/purgatory/Makefile @@ -35,6 +35,11 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS CFLAGS_string.o := -D__DISABLE_EXPORTS CFLAGS_ctype.o := -D__DISABLE_EXPORTS
+# When profile optimization is enabled, llvm emits two different overlapping +# text sections, which is not supported by kexec. Remove profile optimization +# flags. +KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))
# When linking purgatory.ro with -r unresolved symbols are not checked, # also link a purgatory.chk binary without -r to check for unresolved symbols. PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
-- 2.40.1.495.gc816e09b53d-goog
-- Thanks, ~Nick Desaulniers
-- Ricardo Ribalda
linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
Hi Conor
Fixed on my branch https://git.kernel.org/pub/scm/linux/kernel/git/ribalda/linux.git/commit/?h=...
Will submit a new version after a while :)
Thanks!
On Mon, 1 May 2023 at 19:28, Conor Dooley conor@kernel.org wrote:
On Mon, May 01, 2023 at 07:18:12PM +0200, Ricardo Ribalda wrote:
On Mon, 1 May 2023 at 18:19, Nick Desaulniers ndesaulniers@google.com wrote:
On Mon, May 1, 2023 at 5:39 AM Ricardo Ribalda ribalda@chromium.org wrote:
If PGO is enabled, the purgatory ends up with multiple .text sections. This is not supported by kexec and crashes the system.
Cc: stable@vger.kernel.org Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory") Signed-off-by: Ricardo Ribalda ribalda@chromium.org
Hi Ricardo, Thanks for the series. Does this patch 4/4 need a new online commit description? It's not adding a linker script (maybe an earlier version was).
Thanks for catching this. It should have said
risc/purgatory: Remove profile optimization flags
^^Perhaps with the omitted v added too?
Also while playing the $subject nitpicking game, is it not called "profile**-guided** optimisation" (and ditto in the comments)?
Cheers, Conor.
Will fix it on my local branch in case there is a next version of the series. Otherwise, please the maintainer fix the subject.
arch/riscv/purgatory/Makefile | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile index 5730797a6b40..cf3a44121a90 100644 --- a/arch/riscv/purgatory/Makefile +++ b/arch/riscv/purgatory/Makefile @@ -35,6 +35,11 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS CFLAGS_string.o := -D__DISABLE_EXPORTS CFLAGS_ctype.o := -D__DISABLE_EXPORTS
+# When profile optimization is enabled, llvm emits two different overlapping +# text sections, which is not supported by kexec. Remove profile optimization +# flags. +KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))
# When linking purgatory.ro with -r unresolved symbols are not checked, # also link a purgatory.chk binary without -r to check for unresolved symbols. PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
-- 2.40.1.495.gc816e09b53d-goog
-- Thanks, ~Nick Desaulniers
-- Ricardo Ribalda
linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
Hey Ricardo,
On Mon, May 01, 2023 at 02:38:22PM +0200, Ricardo Ribalda wrote:
If PGO is enabled, the purgatory ends up with multiple .text sections. This is not supported by kexec and crashes the system.
Cc: stable@vger.kernel.org Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory") Signed-off-by: Ricardo Ribalda ribalda@chromium.org
arch/riscv/purgatory/Makefile | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile index 5730797a6b40..cf3a44121a90 100644 --- a/arch/riscv/purgatory/Makefile +++ b/arch/riscv/purgatory/Makefile @@ -35,6 +35,11 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS CFLAGS_string.o := -D__DISABLE_EXPORTS CFLAGS_ctype.o := -D__DISABLE_EXPORTS +# When profile optimization is enabled, llvm emits two different overlapping +# text sections, which is not supported by kexec. Remove profile optimization +# flags. +KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))
With the caveat of not being au fait with the workings of either PGO or of purgatory, how come you modify KBUILD_CFLAGS here rather than the purgatory specific PURGATORY_CFLAGS that are used later in the file?
Cheers, Conor.
# When linking purgatory.ro with -r unresolved symbols are not checked, # also link a purgatory.chk binary without -r to check for unresolved symbols. PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
-- 2.40.1.495.gc816e09b53d-goog
linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
Hi Conor
On Mon, 1 May 2023 at 19:41, Conor Dooley conor@kernel.org wrote:
Hey Ricardo,
On Mon, May 01, 2023 at 02:38:22PM +0200, Ricardo Ribalda wrote:
If PGO is enabled, the purgatory ends up with multiple .text sections. This is not supported by kexec and crashes the system.
Cc: stable@vger.kernel.org Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory") Signed-off-by: Ricardo Ribalda ribalda@chromium.org
arch/riscv/purgatory/Makefile | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile index 5730797a6b40..cf3a44121a90 100644 --- a/arch/riscv/purgatory/Makefile +++ b/arch/riscv/purgatory/Makefile @@ -35,6 +35,11 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS CFLAGS_string.o := -D__DISABLE_EXPORTS CFLAGS_ctype.o := -D__DISABLE_EXPORTS
+# When profile optimization is enabled, llvm emits two different overlapping +# text sections, which is not supported by kexec. Remove profile optimization +# flags. +KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))
With the caveat of not being au fait with the workings of either PGO or of purgatory, how come you modify KBUILD_CFLAGS here rather than the purgatory specific PURGATORY_CFLAGS that are used later in the file?
Definitely, not a Makefile expert here, but when I tried this:
@@ -35,6 +40,7 @@ PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss -g0 PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING PURGATORY_CFLAGS += -fno-stack-protector +PURGATORY_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))
It did not work.
Fixes: bde971a83bbf ("KVM: arm64: nvhe: Fix build with profile optimization")
does this approach, so this is what I tried and worked.
Thanks!
Cheers, Conor.
# When linking purgatory.ro with -r unresolved symbols are not checked, # also link a purgatory.chk binary without -r to check for unresolved symbols. PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
-- 2.40.1.495.gc816e09b53d-goog
linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
On Mon, May 01, 2023 at 09:54:43PM +0200, Ricardo Ribalda wrote:
On Mon, 1 May 2023 at 19:41, Conor Dooley conor@kernel.org wrote:
On Mon, May 01, 2023 at 02:38:22PM +0200, Ricardo Ribalda wrote:
If PGO is enabled, the purgatory ends up with multiple .text sections. This is not supported by kexec and crashes the system.
Cc: stable@vger.kernel.org Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory") Signed-off-by: Ricardo Ribalda ribalda@chromium.org
arch/riscv/purgatory/Makefile | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile index 5730797a6b40..cf3a44121a90 100644 --- a/arch/riscv/purgatory/Makefile +++ b/arch/riscv/purgatory/Makefile @@ -35,6 +35,11 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS CFLAGS_string.o := -D__DISABLE_EXPORTS CFLAGS_ctype.o := -D__DISABLE_EXPORTS
+# When profile optimization is enabled, llvm emits two different overlapping +# text sections, which is not supported by kexec. Remove profile optimization +# flags. +KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))
With the caveat of not being au fait with the workings of either PGO or of purgatory, how come you modify KBUILD_CFLAGS here rather than the purgatory specific PURGATORY_CFLAGS that are used later in the file?
Definitely, not a Makefile expert here, but when I tried this:
@@ -35,6 +40,7 @@ PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss -g0 PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING PURGATORY_CFLAGS += -fno-stack-protector +PURGATORY_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))
It did not work.
Unfortunately I am oh-so-far from an expert on this kind of thing, but I had thought that PURGATORY_CFLAGS_REMOVE was intended for this sort of purpose.
Fixes: bde971a83bbf ("KVM: arm64: nvhe: Fix build with profile optimization")
does this approach, so this is what I tried and worked.
That doesn't have a specific CFLAGS though afaict. Perhaps Nick etc have a more informed opinion here than I do, sorry.
Thanks, Conor.
# When linking purgatory.ro with -r unresolved symbols are not checked, # also link a purgatory.chk binary without -r to check for unresolved symbols. PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
-- 2.40.1.495.gc816e09b53d-goog
linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
-- Ricardo Ribalda
linux-stable-mirror@lists.linaro.org
-
Conor Dooley -
Conor Dooley -
Nick Desaulniers -
Palmer Dabbelt -
Ricardo Ribalda