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[libunwind][Hexagon] Save/restore full r0-r7 in getcontext/jumpto (#208753)

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The Hexagon save and restore routines dropped GPRs, producing an
incomplete context.

UnwindRegistersSave.S (__unw_getcontext): save r0-r7 (stores began at
__r[8]), drop a dead "r1 = memw(r30)" before the PC store, and return
UNW_ESUCCESS instead of a stale non-zero value.

UnwindRegistersRestore.S (jumpto): restore the missing r2-r7 (r0/r1 and
r8-r31 were already handled), and fix the stale "pointer is in r2"
comment (it is r0).

Signed-off-by: Kushal Pal <kushpal@qti.qualcomm.com>
This commit is contained in:
quic-k 2026-07-13 18:48:51 +05:30 committed by GitHub
parent 90d8af8caa
commit 7a8b26271b
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2 changed files with 33 additions and 4 deletions
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13
libunwind/src/UnwindRegistersRestore.S
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@ -947,11 +947,22 @@ DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind14Registers_or1k6jumptoEv)
#elif defined(__hexagon__)
# On entry:
# thread_state pointer is in r2
# thread_state pointer is in r0
DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind17Registers_hexagon6jumptoEv)
#
# void libunwind::Registers_hexagon::jumpto()
#
# The context layout is hexagon_thread_state_t: unsigned int __r[35]
# __r[0..31] = r0..r31, __r[32] = predicates, __r[33] = PC.
# Offsets: __r[n] is at byte offset n*4. r0 is the context pointer, so
# it is restored last; r31 is loaded with the saved PC as the jumpr target.
r2 = memw(r0+#8)
r3 = memw(r0+#12)
r4 = memw(r0+#16)
r5 = memw(r0+#20)
r6 = memw(r0+#24)
r7 = memw(r0+#28)
r8 = memw(r0+#32)
r9 = memw(r0+#36)
r10 = memw(r0+#40)

24
libunwind/src/UnwindRegistersSave.S
View file

@ -1103,8 +1103,21 @@ DEFINE_LIBUNWIND_FUNCTION(__unw_getcontext)
# On entry:
# thread_state pointer is in r0
#
# The context layout is hexagon_thread_state_t: unsigned int __r[35]
# __r[0..31] = r0..r31, __r[32] = predicates, __r[33] = PC, __r[34] = unused
# Offsets: __r[n] is at byte offset n*4.
#
#define OFFSET(offset) (offset/4)
DEFINE_LIBUNWIND_FUNCTION(__unw_getcontext)
// Save r1-r7 first (r0 is the context pointer, saved last)
memw(r0+#4) = r1
memw(r0+#8) = r2
memw(r0+#12) = r3
memw(r0+#16) = r4
memw(r0+#20) = r5
memw(r0+#24) = r6
memw(r0+#28) = r7
memw(r0+#32) = r8
memw(r0+#36) = r9
memw(r0+#40) = r10
@ -1134,12 +1147,17 @@ DEFINE_LIBUNWIND_FUNCTION(__unw_getcontext)
memw(r0+#116) = r29
memw(r0+#120) = r30
memw(r0+#124) = r31
r1 = c4 // Predicate register
r1 = c4 // Predicate register
memw(r0+#128) = r1
r1 = memw(r30) // *FP == Saved FP
r1 = r31
r1 = r31 // Store return address as PC
memw(r0+#132) = r1
// Save r0 (the context pointer itself) last
memw(r0+#0) = r0
r0 = #0 // return UNW_ESUCCESS
jumpr r31
#elif defined(__sparc__) && defined(__arch64__)