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| author | Nicholas Piggin <npiggin@gmail.com> | 2020-04-27 21:08:00 +1000 |
|---|---|---|
| committer | Oliver O'Halloran <oohall@gmail.com> | 2020-06-11 12:51:36 +1000 |
| commit | 11ce9612b3aab362e9139bf7a4e7198408af2832 (patch) | |
| tree | ffe27f045b9d0af852e24ff7349a76aa7a8f3420 /Makefile.main | |
| parent | 7f3dfa7fc8478d22a4cd8af45fc636c3ed9737ea (diff) | |
| download | skiboot-11ce9612b3aab362e9139bf7a4e7198408af2832.zip skiboot-11ce9612b3aab362e9139bf7a4e7198408af2832.tar.gz skiboot-11ce9612b3aab362e9139bf7a4e7198408af2832.tar.bz2 | |
move the __this_cpu register to r16, reserve r13-r15
There have been several bugs between Linux and OPAL caused by both
using r13 for their primary per-CPU data address. This patch moves
OPAL to use r16 for this, and prevents the compiler from touching
r13-r15 (r14,r15 allow Linux to use additional fixed registers in
future).
This helps code to be a little more robust, and may make crashes
in OPAL (or debugging with pdbg or in simulators) easier to debug by
having easy access to the PACA.
Later, if we allow interrupts (other than non-maskable) to be taken when
running in skiboot, Linux's interrupt return handler does not restore
r13 if the interrupt was taken in PR=0 state, which would corrupt the
skiboot r13 register, so this allows for the possibility, although it
will have to become a formal OPAL ABI requirement if we rely on it.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[oliver: x86_64 has an r13, but not an r16 so the tests broke]
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
wip: fix __this_cpu() in the test cases
Diffstat (limited to 'Makefile.main')
| -rw-r--r-- | Makefile.main | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/Makefile.main b/Makefile.main index 12aa253..bf0fcfa 100644 --- a/Makefile.main +++ b/Makefile.main @@ -96,7 +96,14 @@ endif CFLAGS := -fno-strict-aliasing -pie -fpie -fno-pic -m64 -fno-asynchronous-unwind-tables CFLAGS += -mcpu=power8 CFLAGS += -Wl,--oformat,elf64-powerpc -ggdb -CFLAGS += $(call try-cflag,$(CC),-ffixed-r13) +# r13,r14,r15 are preserved for OS to use as fixed registers. +# These could be saved and restored in and out of skiboot, but it's more +# robust to avoid touching them. +CFLAGS += -ffixed-r13 +CFLAGS += -ffixed-r14 +CFLAGS += -ffixed-r15 +# r16 is skiboot's per-CPU data pointer. +CFLAGS += -ffixed-r16 CFLAGS += $(call try-cflag,$(CC),-std=gnu11) ifeq ($(LITTLE_ENDIAN),1) @@ -127,7 +134,7 @@ endif # Check if the new parametrized stack protector option is supported # by gcc, otherwise disable stack protector -STACK_PROT_CFLAGS := -mstack-protector-guard=tls -mstack-protector-guard-reg=r13 +STACK_PROT_CFLAGS := -mstack-protector-guard=tls -mstack-protector-guard-reg=r16 STACK_PROT_CFLAGS += -mstack-protector-guard-offset=0 HAS_STACK_PROT := $(call test_cflag,$(CC),$(STACK_PROT_CFLAGS)) |